TM 9-744 155 MM M41

7/28/2019 TM 9-744 155 MM M41

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t- o u r1 5 5- m m H O W I T ZE R

M O T O R C A R RI A G E

M 41

DE PA RTM E NT - S EPT EM BER 1947

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WAR DEPARTMENT TECHNICAL MANUAL

TM 9-744This manual supersedes so muck of TB ORD 20 , 24 January 1944; TB ORD 126, 19 July 1944; TB 9-729-1,

5 September 1944; and TB 9-729-5, 24 April 1945, as pertains to the materiel covered in this manual

155-mm HOWITZER

M O TO R CARRIAGE

M4 1

WA R DEPARTMENT . SEPTEMBER 1947

United States Government Priming Office

Washington : 1947

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WAE D EPARTMEN T

W A SH I N G TO N25, D. C., 17 Sep tembe r 1947

T M 9- 744, 155-mm Ho witzer Motor Car riag e, M 4 1 , is pu blished forthe info rmation and guid ance of all conc ern ed.

The informati on in this m anual is correct as of 1 Ma y 1947.

[A G 300.7 (7 Jan 47)]

B Y O R D ER OF THE SECRETAR Y OF WA R :

OFFICIAL: DWI GHT D. EISEN HOWER EDWARD F . WITSELL Chief of Staf fM ajor G ener alThe Adju tant Gen eral

DISTRIBUTION :

A AF (5) ; AGF (2); T (10) ; D ept (5); Arm & Sv B d (1 ) ;

Tec h Sv (2) ; FC (1 ); PE (Ord O) (5); G en Dep (Ord Sec)(1); Dis t 9 (3) ; Esta bli shments 9 (3) ; Gen & Sp Sv Sch(5) ; Tng Ct r (2); A (ZI) (25), (Ove rsea s) (3); CHQ (2);D (2) ; One (1 ) copy to each of the following T/O & E's:6-437; 9 -7; 9-9 ; 9-65, 9 -67; 9-1 97; 9-316; 9-3 17 ; 9-325.

For ex plan ation of dis tribution formul a , see TM 38-405.

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CONTENTS

PART ONE. INTRO DUCTION Paragraphs Page

Se ction I. General._.. _____ __________ ___-._ _____---- 1-2 1

//. Descript io n and data___ -_ __-_-_______-- .. 3-4 3

PART TWO. OPERATIN G INSTRUCTIONSSection III. Gen eral-___.___ _--- _--_-.------_- ----- _-_ 5 10

I V. Service upon re ceipt of equipme n t........... 6- 9 10V. Controls an d instrument s...-- ------------- - 1 0-12 15

VI. Operation under ordinary con ditions .-------- 1 3-18 25VII. Mount contro ls and operation. ..-_ _......__. 19 -20 29

VIII. Ope ratio n of auxiliary e quipment.----- --- --- 2 1-22 34IX. O per ation u nder unu sua l con ditions--- ------- 23-2 6 37

X. Demoliti on to prevent enemy u se...--------- 27-28 42

PART THREE. MAINTENANC E INSTRUCTIONSSection X I. General . .. .... ................ .... ....... 29 46

N XII. Specia l o rganizational tool s and equipment-- - 30- 31 46XII I. Lubrication-- ------.------..---- ----.----- 32-33 49X IV. Preve ntive m ai ntenance services .-.--- --___-- 34 -40 61

XV. T rou ble shooting-.-.- - ---..----------__ _ -- 4 1-55 90X VI. Engine descr ip tion and maintenanc e in v ehicle- 56- 66 114

XVII. Engine rem oval an d ins tallat ion.......... ... 67-68 129XV7/7. Ig nition system--- -.-.-. -------..--.. ----- 69-75 141

X7X. Starti ng system..--.---_ - _-__-___--_--__ - - 76-79 149

X X. Gene rator and cha rging system.- .. _------___ 80-8 2 152XXI. Batte ry and lighti ng sy ste m___.____-_- _.- . 83-8 7 156XXII. Inst ruments and Instru ment panel---.-- - .--. 88-93 164

XX III. Miscellaneous elec trical equipme nt-- --------- 94- 1 03 166X X/V. Radio inter ference suppres si on---...-------- 10 4-107 173

XXV. Fue l an d air intake and exh aust System s..._. 108 -113 178XXVI. Coo ling system-- -----___ _-----.-__ ---__--- 114-119 191

XX VII. Hydrama tic transmi ssions_ __-______ _._.__ 120- 125 203XXVIII . Prop e ller shaft s and supp ort bearings.--- -- -- 126-12 8 21 0

XX/ X . Transfer unit.- -_-_----- -.---.-__ ------__ . 129-132 21 3

X XX. Contro lled d ifferential - ----- -.-.---------- .133-138 220XXXI. Fina l drive--------- -. ----.---.-------- - -. 139-141 229XX XII. T rack s and suspe n sion---_------.. -_ -....-- 142-153 232

XXXIII . Hull----.....-.. --. - --....--_--- ....-- _-. 154-166 251X XXIV. Fire ext inguisher- -..____- ....-__--__ ___--_. 167 260

III

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PART FOUR. A UXILIARY EQUIPM ENTSection XXXV. General.__..-.._•_...___ - __._---.-----..... 168 262

XXXVI. Armament...-............ ...-.. ..- .----.. 169-171 262

XXXV II. Armament ope ra ting instructions------- ----- 172-17 9 264

X XXVIII. Sighting and fire control equ ipment..._---.__ 18 0-183 274

X XXIX.Ammuniti on..----...--- -.-..------------- 18

4-187279

XL. Radio and inte rphone equ ipment------------ 188-1 92 290

APPENDIX I. SHIPMENTAND LIMITED STORAG E------ ------- 298

II . REFERENCES ----------- ------ ---------- ------- 303

INDEX---.-- --.-----.- -----..------------------- -------- ------- 308

IV

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This manual supersede s so much of TB ORD 20, 24 Januar y 1944; TB ORD 126,19 July 19U; TB 9 -729-1, 5 September 1944; and TB 9-7 29-5, 24 April 1945,as pertains to the m

aterielcover ed in this

manual

PART ONEINTRODUCTION

Section I. GENERAL1. Scope

a. The se instructions are published for the informatio n and guidance of all concerned. T hey contain information on o peratio n and maintenance of the equipm ent a s well as descriptions of the ma joru nits and their func tions in relation to other comp onents of thisvehicle. T hey appl y only to th e 155-mm howitzer motor carriageM 41 and are arranged in fou r parts: Pa rt One, Introduction; PartTwo, Operating In structions; Pa rt Three, Maintena nce Instructions;Part Four, Auxilia ry Equipment and Appendix.

6. T he appendix at the end of the m a nual contains instructions forsh ipment and limited st ora ge, and a list of references in cluding st and ard nomenclature lists, Technica l Manuals, and other publica

tions applicable to the vehicle.

2. Recordsa. G E N E R A L . Forms, records, and reports a re designed to serve

ne cessary and useful purposes. Be sponsibility for the prop er execu

ti on of these forms rests upon commandin g officers of all uni tsoperating and maintain ing vehicles. It is emphasized, h owever, thatforms, reco rd s, and reports are merely aids. They are not a substitute for thorough practical work, physica l inspection, and activesupervision.

5. A U T H O R I Z E D F O R M S . The forms, records, a nd re p orts generallyapplicable to unit s operating and maintaining the se vehicles arelisted be lo w with brief explanations of each. Only approved W arDepartment forms will be u sed in operating and maintainin g the

vehicles. Pending availabil ity of forms li sted, old forms m ay beused. For a cur rent and complete listing of all forms, se e cu rrentFM 21-6.

(1) War Department Lubrication Order. War Departm ent Lubrication Orde r N o. LO 9-744 prescribes lubrica tion maintenan ce forthis vehicle. A lubricat ion ord er is issued with each v ehicle andwill be carrie d with it at all times. Instructi ons contained therein

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ar e mandat o ry to all us ers of the equ ipment and supers ede a ll conflictin g lubricati on instructi ons of prio r date.

(2 ) St andard Fa rm 26 (Driver's Re port cci d ent, Moto r Transportation ). One copy of this fo rm wi ll be kept with vehicle at a lltim es. In case o f an a ccident re sulting in in ju ry or prop erty dam ag e,

it wi ll be fille d out by the driv er on the spot or as promptl y asp ractic able therea fter.

(3 ) War Departmen t Form 30 (Re port of Claims Of ficer). Thi sform will be used by th e claims officer in rep or ting his inv estigatio nof vehicle ac cid ents.

(4) War De par tment F orm 1 (8 (Drive r's Trip Ti ck et and Pr eve ntive Ma intenan ce Service R ecord ). T hi s form, p roperl y exe cute d, willbe furnished d river or o p erator when his ve hicle is disp atch ed on no n-

tactica l missi ons. The drive r an d th e official user of the veh ic le willcomplete in detail ap pro priate p arts of thi s form. This form nee d no tbe issued fo r vehicle s in convoy or on tactical mission s. The reve rse side of this form contains the driver' s dai ly an d weekl y p reventivemaintena nce service sch edule, the accomp lishm ent o f wh ich is man datory.

(5 ) War De partmen t A GO For m 9 -6 9 (Spo t C he ck Ins pe ction Rep ort fo r Al l Full -Trac k and Tank-Like Whee led Vehicles). T hisfo rm is pr ovi ded as a record for use by com ma nders a nd their st affrep resent ative s conduc tin g command insp ections on this typ e of equ ipment.

(6) W ar De pa rtment AG O Form 9 -71 (Loc at or and Inv ento ryContro l C ard). Exc ept when specified oth erwis e by th e War Dep ar tm ent, this fo rm will be us ed as a b in tag, loc ator car d, o r i nventory co ntr ol c ard by all units au thorized au tom otive spare par ts.

(7 ) War De partmen t A GO Form 9- 73 (Data for Regis tr ation).All veh icles w ill be reg istered in th e War Departm e nt M otor V ehicle

Central Re cords Office; Office, C hie f o f Or d nance, W as hington 25,D. C . Attn:OKD FQ. Re gi stration wil l be made b y accomp lishingthis fo rm in ac cordan ce with A R 850-10.

(8 ) War D epa rtment AG O Form 9- 74 (M otor Veh icle O p erator'sP ermit). Th is form wi ll be issue d by com man ders to all o perato rs of v ehic les who are qualified to operate th e parti cula r veh icles n ote d onthe p ermit.

(9 ) War Dep artmen t AG O F orm 9 -75 (Daily Di spatching Record

o f Motor Ve hicles ). T his for m w ill be us ed to keepa

da ily record o fall vehi cles dis patched.(10) Wa r Depart m ent AGO Fo rm 9-76 (R equest for Work Orde r).

This fo rm w ill be u sed for requesting re pairs, alte rations, or othertype of wo rk within o r betw een o rgani zation s and d epa rtments .

(11 ) War D ep artment AGO Form 9- 77 (Job O rder Re gister}.T his form will be us ed to keep a chr onolog ical record of wo rk ord ers.

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(12) "War Departme n t AGO Form 13-1 (Au tomotiv e DisabilityReport of Vehicles DisabledMore Tha n Three Days). Thia fo rm willbe accomplished an d submitted as directed in cu rrent War Depar tment instructions.

(13) War Dep artm ent AGO F orm J / i6 0 (Preven tive MaintenanceRo ster). T his form will be used for schedu ling and mainta ining a record of motor vehicle main tenance o perations (weekly, monthly,quarterly, and se miannuall y).

(14) Wa r De partment AG O Form .$ % (W o rk Sheet for Ful l-tra cka nd Tank-Lik e Wheele d Vehicles). Th is form will be used for maintenan ce services and for all technica l inspections of these vehicles.

(15) W ar Departme nt AGO Form $ 8 (Modification Work O rd er

and Major Unit Assembly Re placement R ecord a nd Orga ni zationE qui pment Fil e). Th is form will be ke pt in possession of second echelon personnel and will accompany vehicles upon tr ansfer and evacua tion to hig h er echelon. It w ill be a record of all modifications mad eand exchanges of ma jor unit assemblies. Minor repair s, parts, andaccessory replac ements will n ot be recorded. In the field, where nofiling facil iti es are available , this form will be k ept in a filing jacket.

(16) War Departm ent AGO Fo rm 4 4 - 1 (Monthly M oto r Ve hicleAccid en t Summary R ep ort). This fo nn will be used to fu rnish amonth ly su mmary of accidents involving vehicles.

(17) Wa r Dep artm ent AGO F orm 811 (Wor k Request a nd Jo bOrder). This fo rm w ill be used by organ izational maintenance unit swhen reque sting repair by a h igher echelon rep air unit.

Section II. D ES C R IPTION AN D DATA

3. Descriptiona. G E N E R A L . The 155-mm how itzer m otor carr iage, M41, is an ar

mored, fu ll-track laying , se lf-pr opelled mou nt for a 155-mm howitzer.It carries 5 of the 12 men who comprise the crew. Of the 5 men carried, 2 travel in the d riving compar tm ent and 3 in se ats on the gunmount. The vehicle is designed with a driving co mpa rtment at thefront , an engine com p artment in the center, and a fight ing compart me nt at the rea r, above which the how itzer mo u nt is assembled. Dualcontr ols are provided for the d river and for emergency operat ion oft he vehicle by the assist ant driver.

b. P O W E RTR A IN . The vehicle is driven by two Cadillac, 8-cylinder,90 , V-type, liquid-cooled engines, th rough tw o hyd ra matic transmissi ons; a trans fer unit with mechanically selected speed ranges, twoforward and one reverse; a co ntrolled differ en tial for steering and braking , which is located in the f ron t of the hull; tw o final drives; and th e necessary connecting propel ler shafts. Wid e steel block trac ksprov ide th e means of propul sion. Tors ion arm suspension is used for

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th e d u al tr ac k wheels, and in clu de s a co mpe ns atin g w heel at the re aro n ea ch sid e to k eep track tension mo re n ear ly uni fo rm on ro ughterr ain .

c. HULL. T he hu ll of th is veh icl e is a com pletel y w el ded st ru ctur e ,exc ep t fo r po rt ions o f the front, to p, a nd floor, w h ich ar e rem ov able fo r serv ice op era tion s. Th e hul l is di v ided into th ree c om par tm ent s:The dri v ing co mpar tment at the fr on t, the engin e co m part m ent in th e center, an d the f ig htin g c ompa rtmen t at th e rea r, abov e wh ich ism ounte d th e 155-mm how itzer. The driv ing a n d eng ine co m par tmen ts are se pa rate d by a bulk he ad th at ex tend s fro m si de-t o-s ide, a nd from th e roo f dow n to th e bulk he ad ex tens io ns, w hi ch in tur n extend forwa rd far enoug h to co ve r th e t ran sfe r u nit. Th e en gine andst ow age comp artme nts a re se pa rate d by a b u lkhea d tha t exte n ds fro mside-t o -side and from roo f-to -flo or. A spad e a nd gu nn er's pla tf orm

ass embly is hing e d to bra ck ets m o unte d on th e hull at the re ar o f the veh ic le. W hen the spade an d p latform ass embly is in t h e rai sed po s itio n it se rves as a tai lga te. The spade an d p latf or m ass embly in the lo we red p osit io n p rovid es a p latfor m for the gu nne r an d th e spa de act s as an anch or to k eep th e veh icle in p ositi on w h en th e gun is fired .T he sp ade assemb ly is ra ised a nd low er ed b y a h and o perat e d w in ch.

Th e f ron t o f the hull slo pes d ow nw ard a t the top an d upw ard a t th eb ottom to fo rm a V. The sides of th e hull slope inw ard at th e botto m .L ifting eyes are p rovid ed and shou ld alwa y s be u sed w hen th e veh icleis to be l ifted .

d. H O W I T Z E R . Th e h owit zer, mo unt, and sh ieldin g are m ou nte d at the re ar o f the vehi cl e. The m ou nt p rovi de s 5° dep ressio n , 45° eleva tion, 2 0 r ight tr av ers e a nd 17° le ft trav e rse.

4. T ab ula te d D ata

a . G EN ER A L.

Pu rp os e.— — _— _ __ __ __ __ __ __ __ _ __ _ Mo bile a rtiller y .

Ty p e— — —_ — — — —_ _ ___ _ _— __ ___ _ ___ F ull-tr ack lay ing.C rew — —— — — — —— —_ _- ____ _ _— __ ___ __ ___ __ ___ 12 m e n.

Weigh t (w ith fu e l, amm uniti o n, an d cre w )__ ___ _ __ 42,500 Ib. L en g th— _ __ __ __ _ ___ _ ___ _ ___ _ ___ _ __ __ __ __ 230 in. W id th— _.. __ __ __ __ _ ___ _ __ __ __ __ __ _ __ __ _ 112 in.H e igh t, o ve r- alL — __ _ ___ _ ___ _ ___ _ __ __ __ _ ___ _ 96 in .G rou nd clea r anc e —_ _ ___ _ ___ _ ___ _ ___ _ ___ _ __ 17% in.G round p ressu re at 1-inch p ene tr atio n_ __ __ __ __ __ __ 8.816 ps i.

J. MAXIMUM O P E R A T IN G C H A R A C T E R IS T IC S .

Sus tained sp ee d_ __ _ __ __ __ __ __ __ _ __ __ __ __ _ 30 mph . G ra de, asc end ing o r desc endi n g__ _ ___ _ ___ _ ____ ____ 60 p e t.W idt h of d itc h_ __ _ __ __ __ __ __ __ __ __ __ _ __ __ __ _ 9 f t.V er tica l obs tacle ____ ____ ___ ____ ____ ____ ____ _ 40 in.Ford ing d ep th -— _ ___ _ __ _ ___ _ __ __ __ _ ___ _ __ 42 in .

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Hull floor:Ahead of second pair of torsion springs_—____—__ y in .Behind second pair of torsion springs____________ % in.

Hull rear (tailgate thickness) ___________________ 14 in .h. E L E C T R I CS Y S T E M .

Voltage_____________________..____________ 24.Batteries—_____—_—__—____—___ 2, (comprising tw o 6-cellunits in series).

Battery locations_______________ 1, each side of vehicleengine compartment.

Battery master switch-—___—______ On bulkhead just behinddriver's seat.

i. C O M M U N I C AT I O N S .Radio______-_________.____. SCE 619 or SCR 610 or

BR 19 (24 volt).Interphone RC99________________________ 3 stations.Other—_—_____—__________. Signal flags, flares, iden

tification panels. x

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c. B ring deficiencies of a serious na tu re to the a ttention o f thesu pplying o rg anization through prop er chann els .

8 . Specific Proceduresa . PRELIMINARYSERVICE. Before the v ehicle is mo ved to make

actu al run-in test, certain insp ecti ons an d se rvices w ill be pe rfo rmedas fo llo ws:b . INSPECTIO N S A N D SERVICES (1 ) Fire ex ti nguishers. See that

the po rtable- and fixed-sy ste m cy lind ers are se curely stowed . Inspectth e o perating valve s. I f th e valve s appear to have been opene d ord amaged, rep ort to pro per a uthori ties for ex change or refill. Examin e the lines, nozzles, a nd co nt rol cables of the fixed system to see that they are in goo d con dition and that the nozzles a re not clog ged .

(2) F uel, oil , an d water. F ill fuel tan ks. C heck level of co olantin radi ato r and ad d as nec es sary to bri ng to corre ct level. A llow roo m fo r expa nsi on in fu el tanks and radiator s. Durin g freezingweath er, te st streng th of a ntifree ze a nd add as necessa ry to prote ctsystem aga inst freezin g. Check level of oil in each eng in e. Cautio n:

If the re is a ta g at tached to th e cra nkcase fill ed caps concern ing eng ineoil in cran kcas es, fol low instru c tions on tag s before d riving vehicle .

No te. V ehicles shipped fro m depots may h ave whit e unleaded g asoline inthe tan k s. This sh ould be drain ed and 80 oc tane us ed for filling.

(3) Fuel st raine r. In spect the fuel str aine r at each carbure torin let elbow for le aks or damag e. R emove str ained bowl and cleanout an y accumul ation of fo re ign matt er. Be su re, tha t bot h fue lswitc hes and shut-of f valves o p erate prope rly. Drai n accumul a tedd irt and w a ter from bottom of fu el tank s. Drain o nly until fuel runsclean.

(4 ) B atter ies. Remov e batte ry covers and c lean any a ccumulatedd us t or dirt from tops o f batterie s. Make h ydro meter and voltage

test o f batterie s and if n ecessary, ad d dist illed or clean water tobring ele ct rolyte to y inch above p lates.

(5) Air cleane rs an d brea thers . Exa mi ne carbu retor air c lea nersan d chan kc ase breat her c leaner s to see tha t the y are in good con diti on and sec ure. Remov e air-clean er elemen ts , wash in d ry- cleaning solve nt, and fill reservo ir s with oil te the cor rect level as direc ted inlubri ca tion order (pa r. 32). R einstall securely, a n d make su re allconne ction s are in goo d condit ion and duct s and air-hor n connec tio ns

are tig ht.(6 ) Accessori e s and belts . See that accessories suc h as c arb uretor,

generato rs, regulat o rs, d istribu tors, starte rs, water p u mps, and fanson both eng ines are sec urely moun ted and tha t d rive belts are in goo dco nditio n and adju sted with % - to %-in ch, finger-p ressure defle ctio n

(fig. 50 ).

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(7) Electrical wiring. Inspect all accessiblewiring and conduits tosee that these parts are in good condition, securely connected andproperly supported.

(8 ) Tracks. Clean all foreign material from tracks and suspensionunits. Examine track blocks for damage and for loose or damaged

nuts and screws. S ee that tracks are correctly assembledand mountedand that tension is adjusted so that there is %- to 1-inch sag betweenthe second and third support rollers (fig. 128) .

(9 ) Wheel and flange nuts. S ee that operating compensating wheel,track wheel, sprocket, and support roller assemblymounting and flangenuts are present and secure.

(10) Fenders and shields. S ee that fender brush guards and sand-shields (if so equipped) are in good condition and secure and thatshield hinges operate properly.

(11) Towing connections. Examine towing loops, pintles, and guntraveling lock for looseness and damage. Be sure that pintle hookand gun traveling lock operate properly and lock securely.

(12) Hull and tarpaulin. S ee that all hull attachments, hardware,lift loops, doors and their releases and locking mechanisms, are ingood condition, secure, and operating properly. Examine all hulland gun mount attachments for looseness and damage. Be sure hulldrain valves open and close freely. Inspect tarpaulin or camouflagenet to see that these items are in good condition, and mount or stowthem securely. M ake sure there are no bright spots to cause glare,and that all markings are legible.

(13 ) Vision devices. Inspect periscope prisms and windows(mounted or spares) to see that they are in good condition and clean.S ee that mounted units are secure in holders, and that holders areproperly mounted. Test each periscope to be sure it will elevate,traverse, and depress through full range.

Caution: Clean periscopeonly with a soft cloth or brush.(14 ) Lubrication. Perform a complete lubrication of the vehicle,

covering all intervals according to instructions in the lubricationorder except gear cases and units lubricated or serviced in items (1 )to (13). Check all gear case oil levels and add as necessary to bringto correct levels; changeonly if condition of oil indicates the necessity,or if oil is not of proper grade for existing atmospheric temperature.

Note. Perform items (15) to (18) (hiring lubrication.

(15) Suspensions. Examine all suspension arms, brackets, shockabsorber links, and guides to see if they are in good condition, correctly assembled, secure,and not leaking excessivelyat seals. Inspectsprocket teeth for damage or excessive wear. Be sure road wheel andsupport roller' tires are in good condition and that rubber is notseparating from rims. While applying lubrication, examine sealsfor excessive leaks.

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(16) Steering lin ka ge. Inspect al l shaf ts, arms, rod s, connections,le vers, and grips to see if th ey are in good conditi on , correctly andsecu rely asse mbled an d mounted , and that they ope rate w ithout excessive looseness or b inding. Check brake link age adjustment b ypulling back even ly to make sure free travel is equ al and does notexceed six notches, and tha t brake s a re full y appli ed wit hin threeadd it ional notches (par . 134). Be sure parking brak e mechanismlocks the brak e p roperly in the locking po sition.

(17) P rop eller shafts. Remove a ll pro pel ler shaf t covers , a nd insp ect sh afts a nd uni v ersal joints to see if they are in g ood condition,correctly asse m bled, alined , secure, and not leakin g excessively at seals.

(18) Choke. Befo re sta rting engines, see tha t choke ope rates fr eely (fig. 94). W h en s tarting en g ines in item (1 9), observe ifaction of automatic choke is satisfac tory. Adjust choke set ting, ifn ecessary, accordin g to instr uctions (par. 1 10).

(19) Engi ne warm-up. St art engines, n otin g if cranking m otoractio n is satisfactory, and any tendency toward difficult s tarting, inadequate crank in g speed, or unus ual noise. Set ha nd throttle to idl eengines at 625 revolution s per minute durin g warm -up.

(20) Instruments, (a) Warnin g signal s. D o n ot drive vehicl ew hile engi ne or tra ns mission wa rnin g signals a re ligh ted .

(&) Ammeter, Am meter sh ould show sligh t positive •( + ) charge

at eng ine spee ds above 1,400 re volutions per mi nute. High ch ar gema y be indicated until gene rator restores to battery curre nt used in startin g.

(c) E n gine tem peratwe gages. Eng ine temperature shou ld risegr adually during w arm-up to norma l oper ating range, 160° to 180° F.Maxi mum safe operatin g temperature is 240° F.

(d) Tacho me ters. T hese instr umen ts sh ould re gister engine spee din rev o lutions per mi nute, and rec or d accumulating eng inerevol utions .

(21) Engine controls. Observ e if eng ine resp onds pro per ly tocontrols an d if controls opera te without excessive looseness or bin ding.

(22) Ignition timing. Check ignition tim ing and reset if n ecessa ryas soon as engin e is warm, an d before driv ing vehicle (par. 73 ).

(23) Siren. See if s iren is in good condition and secure. Iftactical sit u ation permits, te st for proper oper atio n and to ne.

(24) Lamps ( lights] and reflectors. C lean lenses and in spect allunits for

looseness and da m age. If t

actical situation permi ts, openand close all light sw itches to see if la mps respo nd prop er ly.(25) Leaks gener a l. Look under vehicle and withi n en gine a nd

fighting comp artm ents fo r ind ic ations of fuel, oil, or coolant lea k s.Trace any leaks found to their source, an d correct or repo rt them tohigher autho rity.

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(26) Tools and equipment. Check tools and vehicle stowage tobesure all items are present, and see that they are serviceable andproperly mounted or stowed.

9. Run-in Testa. P R O C E D U R E S .Perform the following procedures (1) to (10)

inclusive during the road test of the vehicle. If the vehicle has beendriven 50 miles or more before delivery to the using organization,confine the road test to the least mileage necessary to make observations listed below.

Caution: Avoid continuous operation of the vehicle at speeds approaching maximums indicated on the caution plate during the roadtest,

(1) Dash instruments and gages. Do not move vehicle until enginetemperature reaches 140° F. M aximum safe operating temperatureis 240° F. Observe readings of ammeter, tachometers, temperaturegages, and warning signal lights to be sure they are indicating theproper function of the units to which they apply. Warning signallights go on when ignition is turned on, and go off as soon as oil pressure builds up. S ee that speedometerregisters vehicle speed and thatodometer records accumulating mileage.

(2 ) Brakes: steering and parking. Test steering brakes to seewhether they will stop vehicle effectively with levers even, and thatthey start to meet resistance at approximately 6 to 8 notches fromfully released position. S ee that parking lock mechanismholds leversin applied position. Test levers separately to be sure vehicle steersproperly with normal pull.

(3 ) Transmissions and transfer unit. Vehicle should start satisfactorily in either "DRIVE" or range. Be alert for abnormalconditions in transmissions, indicated by excessive slippage andengines racing when under load, severe shifting, or shifting in wrongspeed range, also unusual conditions in transfer unit, indicated byhard shifting or severe gear clash. Gears should- operate withoutunusual noise and not slip out of mesh during operation.

(4 ) Engines. Be on the alert for any unusual engine operatingcharacteristics or unusual noise, such as a lack of pulling power oracceleration, backfiring, misfiring, stalling, overheating, or excessiveexhaust smoke. Observe if engines respond properly to all controls

and if control synchronization appears to be satisfactory.(5 ) Unusual noises. Be alert throughout road test for noise fromhull or attachments, suspensions, running gear, or tracks that mightindicate looseness, damage, excessive wear, or inadequate lubrication.

(6) Halt vehicle at 10-mile intervals or less for service. Refer to(8 ) below.

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Section VI. OPERATION UNDER ORDINARYCONDITIONS

13. Use of Instruments and Controls in V ehicular Op erationa. NEW VEHICLERUN-IN T E S T. Before a new or reconditioned

vehicle is placed in service, be sure that the new vehicle run-in testdescribed in paragraph 9 has been performed.

6. BEFORE-OPERATION SERVICE.Perform the services in items (1) to(6) in paragraph 36 before attempting to start the engines. Startand warm up engines (par. 1 4 ) and complete the before-operationservices.

Caution: Only gasoline with an octane rating of 8 0 or above canbe used safely in this vehicle. Normally, the engines will not detonate(knock); if they do, it indicates either that the gasoline is of incorrectgrade or that the ignition timing is incorrect. Check grade of fuel orreadjust ignition timing (par. 73).

14. Starting Enginesa. STARTING. Under normal conditions, the engines should be

started as follows: Set brakes. Place transmission selector lever inNEUTRAL, and place transfer unit shift lever in the range in whichthe vehicle is to be driven. Turn fuel pump on for right or left tank.Turn on ignition switches for both engines, which will cause engineand transmission oil pressure signals to go on. (If the signals do notlight, make sure emergency ignition switch is turned on.) Pressstarter buttons for both engines until engines fire.

Caution: It is important to turn electric gasoline pumps on beforeattempting to start engines, and equally important to turn them offwhen the engines are stopped. Do not allow pumps to operate on adry tank.

6. WARM-TIP. After engines have started, pull hand throttle out toset idling speed at about 625 revolutions per minute, to prevent stallingduring warm-up. Check to see that oil pressure warning signals goout. If these signals remain lighted, shut off engines and investigatecause. Check ammeter to see that generators are charging. Listenfor unusual noises in power train or engines. The engines do not require any warm-up period in mild weather, except the time requiredto check the gages mentioned above. At temperatures below freezing,the warm-up periods given in paragraph 24 should be observed.

c. FLOODING. If engines do not start readily in mild or warmweather, check for flooded condition. This can usually be correctedby depressing accelerator fully and holding it down while crankingengines. As soon as the engines start, close throttle to prevent"racing." Flooding usually occurs more severely in one engine sothat one engine starts and the other does not. In this case, shut offengine that is operating, press accelerator all the way down, and crank

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floodedengine until it starts. The other engine can then be restartedwith a minimum of "racin g." Flooding may be caused by dirt onneedle valve, or by stuck choke shaft. The stuck choke shaft can befreed as shown in figure 94.

d. S T A R T I N G O N E ENGINEW I T HT H E O T H E R .If only one engine

starts readily, it can be used to start the other engine by placing thetran sfer un it shift lever and the transmission selectorin NEU TRAL,run ning the other engine at about 2,000 revolutions p er minute, and then mo ving transmissionselectorlever to DRIVE.

Cauti on : Inspect "dead" engine to be sure it turns over freely b eforea ttem pting to start it by use of the other engine.

e . C O L DW E A T H E R ST A R T I N G .Seeparag ra ph 24 for detailedinstruction on cold weatherstarting and warm-up.

15. Driving Vehiclesa . D R I V I N GR A N G E S .Normally,the vehicle is driven with the trans

missio n selector lever in DRIVE and the transfer unit shift levereither in HIGH or in LOW range. Transfer un it H IGH range provides cruising gear ratios,and is to be used fo r traveling on roads or onrelatively smooth, level terra in. Transfer unit LOW range providespower gear ratios, and is to be used for hill-climbingo r for rough,

sandyor muddyconditions.

Cauti on: Before driving vehicle m akesure that gun is lowered andsecure in trave l lock, and that spade and gunner's platform are raisedand locked in closed position (par. 19J and c). To start vehicle,sh ifttransf er unit into HIGH or LO W,as conditionsw arrant, move transmission lever to DRIVE, release par king brake controls and depressaccelerator. Vehicle will sta rt moving fo rward at a speed in p ropor

tion to the amountthe acceleratoris depressed. The vehicle will startout in first gear and the transmission will automatically shift intosecond, third, and fourth gears as the vehicle speed increases andengine load decreases. Asvehicle loses speed,either becauseaccelerator pedal is released or due to upgrade,the transmissionwill sh ift downautomatically toa lowergear.

c. STEERING. To steer veh icle, pull back on the righ t-hand steeringlev er to make right tur n, or on the left-hand le ver for a left turn.

The lever that is b eing used should be applied firm ly and then released fully, and this acti on repeated if neces sary. The le ver shouldnot be held in a sligh tly applied po sition for long p er iods of time.

C aution: It is very important tha t the ste ering levers be held farenough fo rward to insure complete release of the bands at all times,except when stee ring or stoppin g; oth erwise, brak e lining wear willbe excessive and oil will become overheated.

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d. R E V ER S E . To op erate vehicle in reverse, first brin g i t to a complete stop if in motion; then depress the neut ra l pedal t o pu t thetransmi ssio ns in N EUTRA L, and move the trans fe r unit shift leverup to NEU TR AL, over to the left and forw a rd into RE VERSE.Release the ne u tral ped al. Four speeds autom at ically selected in thehyd ram atic tra nsm issions are avail abl e in reverse.

N ote. Depressing the neut ral pedal puts both tran smissions in neu tral bymeans of the sam e link age as the selector lever, b u t leaves the driver's righ t hand free to shif t the transfer unit. Releasing the pedal puts the tr ansmis sionback in the range for which the selector lever is set. Ne utral ped al should beused only when thrott les a re closed.

e . R O U GH TERRAIN. In nego tiating r ou gh or sand y terrain orheavy mud, n ot only should the tra nsfe r unit be shifted to L OWrange, b ut the tran smiss ion selector lever should also be m oved to

LOW ra nge to ho ld the transm is sion in second gear, and thus o btain the benefit o f a st eady pull . W hen the transm issio ns are in L OWrange, t hey will up-shi ft only from first to second speeds, and will n ot go into third and fo ur th, thus p ermitting a steadier p ull throu gh v ery bad terr ain, or pro vid ing more brak ing effect from engine compr ession when descending hills. Do not allow th e engine speed to exceed 3,500 rev olutions per mintite fo r sus tained periods.

N o te . In negot ia ting long gr ades if trans m ission co nt inually down-shifts and

up -shifts back and forth, tra nsfer unit must be shifte d to high ran ge to allowtrans mis sion to op erate in its higher ranges.

/. DES C E N D I N GHILLS. In descending mo derately steep hill s, t hetransf er unit should be shifte d into LO W ra nge b efore starti n g todescend. When descending long, very steep hil ls, the tran smissi onselecto r lever should also be placed in LOW ran g e before sta rting todescend, and bra kes should be used to keep engine speeds below 3,500revolutio ns per min ute.

Cau tion: Trans fer units sh ifts from H IGH to LO W m ust be madea t speeds below 10 miles pe r hour. The NEUTR A L pedal m u st alwaysbe depressed when ma king the sh ifts.

16. Sto p ping V e hicle

To stop the vehic le, release th e accelera to r and pull back on bo th leversat the same time. There is no clutch to disengage. Both levers shouldbe pulled back and en ga ged with he avy pressu re, and the n released ful ly. If the stop is to be made from relativ ely high speed, it is advisable to use heavy press ure inter mi ttently ra th er tha n a continuou sb ut lig hte r press u re.

Ca utio n: Do no t press down on ne u tral pedal when stopp ing, unless the tran sfer unit is to be sh ifte d. Do not use neutra l pedal as a c lutch when starting.

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17. Stopping EnginesTo stop the engines, close the throttle until engines are idling at approxim ately 450 revolutions per minute. Bun at this speed for 3 or 4minutes and then turn off both igni tion switches and shut off the fuelpump switch. If engines are extremely hot, run at 2,000 revolutions

per minute for a few minutes to cool down before reducing speed ton ormal idle. Finally, open master battery switch.

Caution: Always turn off ig nition switches before openin g masterbattery switches. Neveroper ate engines with master switch off.

18. Towing Vehiclea . TOWING T O S T A R TVEHICLE. The engines can be started in an

emergencyby tow ing th e vehicle, provided the following pr ocedure is

observedafter checking to make sure the engines turn freely:(1 ) Keleasebrakes.(2 ) P lace tran smission selector lever in NEUTRAL and transfei

unit shift lever in LOW.(3 ) When speed reaches appro xima tely 4 miles per hour, turn on

bo th ig nition switches and one fuel pump switch, and move transmission selectorlever toDRIV E.

(4) Continue towing unti l engines fire.

b. TOWINGA D ISA B L E DVEHICLE. When towing a vehicle, severalprecautio ns must be ta ken:(1 ) Tow the vehicle with the tran sfer unit in NEUTRAL, if pos

sible. If transfer unit is damaged or disabled, disconnect the propeller shaft at the controlled different ial pinion sha ft yoke.

(2) If controlled differential is disabled, disconnect the tw o shortprop eller s hafts at the final dri ve yokes.

(3) If final drive units are disabled, break tracks and tw o vehicleon track suspension wheels.

Cau tio n: Tow bar must be used unde r these circumstances.c. TOWINGP R O C E D UR E S . In towing a vehicle, changes in directi on

must be made by a serie s of slight turns so that the vehicle beingto wed is, as nearly as possible, dire ctly behind the one doing the towing. This pr events the cable from contacting the track whichmight damage both the cable and track blocks. If no operato r isav ailable to ste er the disabled vehicle,or if it is being towed wit h the

tracks removed, the cable should be attached by the "short hitch" inwhich it is threaded throug h both eyes on the vehicle to be towed,and the n crossed and passed through b oth shackles of the towedvehicle.

Cau tion: Tow bar must be used when towing vehicle with tr acksremoved.

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Section VII. HOWITZERMOUNT CONTROLS A N DOPERATION

19. Controlsa. G E N E R A L .The howitzer mount is located at rear of vehicle and

is assembled on a continuous bearing. The mount may be traversed

17° to left or 21° to the right by means of a hand crank. T he mounthas tw o travel locks consisting of a traverse and a howitzer lock. Bothtravel locks (fig. 16) should be used when the vehicle is being drivenover the terrain. T he howitzer can be elevated 45° or depressed 5°from the horizontal position by means of a hand crank or an electricalmechanism. The rear of the vehicle is fitted with a spade and gunner's platform which serves as a tailgate when in the RAISED position and as an anchor and platform when in the LOWERED position(figs. 14 and 15) .

b. WIKCHCRANK (fig. 14) . The winch is operated from either endof the crankshaft by one or both of the cranks provided. When operat-

S PA D E WINCH C R A N K WINCH BRAKE LEVER

WINCH

C R A N K

P I O N E E R GUNNER'S

TOOLS P L AT F O R M

P L AT F O R M

T R AV E LL O C K

\

S PA D E

T R AV E LL O C K

Figure 1 4 - Spade and, gunner's platform.

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ing the winch from the gunner's compartment, the crank is turnedcounterclockwise toraise the platform and spade assembly, and clockwise to lower the assembly. W h e n operating the winch from the sideof the vehicle the crank is turned clockwise to raise the spade andplatform assembly, and counterclockwiseto lower the assembly.

c. WINCHBRAKEL E V E R(fig. 14) . The winch brake lever is locatedon the right side of the winch frame. The lever is moved toward therear of the vehicle to apply the brake.

d. WINCHLOCKINGPAW L . The locking pawl is located on the frontright side of the winch frame. The pawl is hand-released when tension is on the cable, by turning the crank in the gunner's compartmentcounterclockwise. The locking pawl when engaged with the drumgear provides a safety lock while raising the platform and spadeassembly.

e. S PA D ET R AV E LLOCK (fig. 14) . The tw o spade travel locks aretoggle latches, bracket-mounted on the rear of the vehicle. The latchesengage studs on the spade when the spade assembly is in the raisedposition. The travel locks are swung upward to release and downwardto lock the spade assembly.

/. P L AT F O R MLOCK (fig. 14) . The tw o platform locks are pivot-mounted on the arms of the spade. The locks are used to hold theplatform in the closed position when the spade is raised.

g. H O W I T Z E RT R AV E LLOCK (fig. 16) . The gun travel lock is mountedon the hull roof above the driver's compartment. The lock is used tohold the weapon tube in traveling position. The lock is secured byswinging up to a vertical position,clamping upper half of lock aroundtube and tightening clamp nut. The lock is released by looseningclamp nut at top of clamp, tilting nut away from gun tube, and liftingupper half of lock away from weapon tube.

h. T R AV E R S ELOCK (fig. 16) . T wo traverse locks consisting of lock

clamps and lock nuts and are mounted on the rear of the weapon base.The locks are used to secure the howitzer and take the play out of thetraversing mechanism. The locks are released by inserting end ofutility bar in hole in clamp nut, looseningnut until lock clamp can befreed from weapon mount base. The locks are secured by placing thelock clamps in position at rear of weapon base and tightening clampnuts.

i. TRAVERSINGH A N D W H E E L(fig. 17). The traversing handwheelis located at the rear left side of the howitzer. It

isused to traverse

the howitzer after disengaging travel lock, traversing locks, and elevating howitzer slightly to clear travel lock.

j. HAND-OPERATINGELEVATIONW H E E L(fig. 17). The hand-operating elevation wheel is located at the rear left of the howitzer. It isused to raise or lower the howitzer manually. Before using the hand-operating elevation wheel, the control lever in the elevation mechanism

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(3) To remove the hea d from the pe riscope body , turn the two.eccent ric assemblies lo ca ted on the side s and u pper par t of the periscope body un til the hea d clam p is completely disengaged from thelatche s of the eccentric me chanism and lift the head from the pe riscope b ody. When ins talling the h ead, position it on the top of the

p eriscope body with the w indow facing the front side o f the perisc ope.Turn the ecc entric assemblies un til the referen ce arrow on each eccentric m atches the corr espo nding arro w on the periscop e body. See thatth e h andles of the eccentric mecha nism lay flat on the sides of theperiscope bod y.

Section IX . OPERATIO N UNDER UNUSUAL C O NDITIONS

23. ColdWeath e r

Preparationa. G ENERA L. The opera tion a nd main ten ance of this veh icle at low

temperatu re s invo lves facto rs which do not exist at normal te mperatures. Sin ce subz ero te mperat ures affect both metals and lubri cants,p roblems are pr esented that de m and special p rec autions. Op erat orsan d maintenanc e p erso nnel must sp en d more time in pro tective main tena nce. Failure to g ive this extra ser vice will result in actua l damage,u n necessary and u nwarr anted expense, and failure to start.

& . F U E L S. (1 ) Pre scribed fuel'. Winter gr ad es of gasoline ar e designed to r educe cold weat h er st arting diffic ulties ; th erefore, use thewinter grade fuel d uring cold weath er opera ti on. Use winter grad egasoline p ro cured un der U nited States A rm y Specificatio n 2-103,grade C, lat es t revision.

(2) Sp ecial preca utions . The fo rmation of ice c rystals f rom smallquant ities of wa ter in th e fuel sometim es causes conside rable troub le.The foll owing precautio ns should be foll owed to keep w ater o ut ofthe fuel tanks:

(a) S train fuel throu gh suitab le stra ine r. Caution: A positive m et allic contac t m u st be provided b etwee n fuel cont ain er a nd fueltank u nless both f uel tan k and con tainer are indepe nde ntly grou nde d.

(b) Alw ays keep the fu el tank as full as possible. This will redu cecondens ation of water from the free air space ab ove the fuel .

(c) Add 1 q uart of de natu red al cohol (gra de 2) to each ta nk o ffuel at sta rt of w inter season and 1 pint to each 10 ga llons o f fuel ateach re fueli ng. The a lcohol will a bsor b the water an d p revent it

from free zing.(d) Do n ot store fue l in old oil or ga soline drums unle ss they havebeen thoroughly cle an ed.

(e ) Never pum p fuel drums dr y when filling the vehicle fuel tan k s;allo w abou t 4 inches of fuel to remain. Thi s residue can la ter betransferre d to a settling tan k . I f time is no t an urgent co ns ideration,do not pump fuel fr om drum to v ehicle until it has settled for 24 hours

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aft er filling or moving. Keep p or tab le fuel pumps clean and pro tected from snow an d fr o st.

(/) W hen a dr um has been opened, be sure th at th e op ening is covered or the b ung repl aced to p reve n t snow, fr ost, or ot he r f or eig nma tter from ent er ing . Stor e dru ms in a covered b u ildi n g o r cover

the m w ith ta rp aul in .c . L U BR IC AT IO N . (1 ) General. Lu b rica ti on above 0° F . is covered

in th e lub ric ati on ord e r. T he fo llow ing in stru c tion s ar e in te nd ed tosup plem ent this infor m atio n and app ly only in inst an ce s where th etem p erat u re fa lls below 0° F. for long periods.

(2) W h ee l and tr ack roller bearings. If vehicle has been driv en1,000 miles u sing gene ral purpose g re ase (No. 0) for lubr ic atio n , nospecia l pr ec au tio ns ar e necessary for th e wheels and tr ack rolle r bear

ings. I f qu antit ies of ge n eral p urpo se gr ea se (No. 1) a re in these bea rings , it will be necessary to disassemble and wash in d ry cle aning solvent, dry and t hen relubr icate w ith gen e ral p urpos e grease (No. 0)for sat is fac to ry op eratio n.

d . C O OL I N G SYST EM. (1) Ant ifr ee ze . Cooling systems will be pro tecte d wit h ant if ree ze compound for op er ati on below +3 2° F . Th efo ll owi ng inst ructi o ns a pp ly to use of new ant ifre ez e compound. Fo ruse of rec lai m ed an tifr ee ze solutions, re fe r to T M 9-850.

(2) C le ani ng cooling sy ste m . I f the cooling system has been cleanedre cen tly, i t may be necessary only to d rai n, refill with clean w ater,and aga in dr a in. O the rw ise , the system can be cleaned wi th cl ean in gcompound (pa r. 115).

(3) D rai n ing cooling sy st em . Ea ch cooling system (40 -q ua rt capaci ty) is dra ined at one p o int; that is, a p lu g mark ed "W AT EK" in th e bot to m of each tr ansm issio n oil pan (fig. 27). Remove thera di ato r cap for ra p id and complete dr ai nin g o f the system.

(4) Leaka ge inspection. Ins p ect al l hoses and rep lac e if deteri o rat ed . Insp ect hose clamps an d p lugs and tig hte n if necessary.R ad ia tor leaks will be repair ed before a ddin g ant ifre eze compound.Co rrect exha u st ga s or air leakage int o the cooling system. Ti gh ten th e cy lind er head screws if th ere is an y in d ica ti on o f a co ola nt leakage.R ep la ce the cy lin de r he ad gas k et if necessary.

(5 ) Ther m ost a ts. Inspe c t th erm o stat s to see th a t the y close com pletely. Look fo r evidence of s ti ckin g in open or closed position.Op er ati on of ther m osta ts can be checked by h ea tin g in~a p a il of wat er

to make certain th a t they will open in hot water. If a th erm o sta tdoes not open or close completely, does no t f unc ti on fr eely, or is bad lyru sted, it should be replaced.

(6 ) Addi n g an tifree ze. When the cooling system is clean an d ti g ht,fill the system w ith wa ter to about on e-thi rd cap acity . T h en add a n tifreeze compound to the cooling system as indi ca ted below. T he system

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should be p rotected to a t le ast 10° F. below the lowest ex pected temperature to be experienced duri ng the winter season.

Pin ts, ant ifreez e compou nd(ethylene glyco l type)

Fr eezing points per system10° F. 20

0° F. 25

-10°F . 30-2 0° F . 35- 30°F. 40-40° F. 45-50°F . 50

After a dding ant ifreeze co mpou nd, fill with wate r to the prescribe d

level; then sta rt and warm the engine to normal operatin g tempera ture. Stop the engine and che ck solutio n w ith a hydrome ter, a ddingantif ree ze compound if required. In serv ice, inspect the coo la nt w eeklyfor strength and color. Ru sty solu tion should be drained, the coo lingsystem thoro ughly clean ed, a n d new solution of the required stren g thad ded.

e. ELECTRICALSYSTEMS. (1) Ge nerator and c rank ing motor. Check the brushes, armature comm ut ators, a nd bea ring s. Be sure that thearmature commutato rs ar e clean. Th e large surg es of current w hichocc ur in starting th e cold engines req uire g ood contact b etween brushes and arm ature commutato rs.

(2) Wi ring. Check, clean, an d tighten all co nne ctions, especiallybattery terminals.- Car e must be taken that no short cir cuits arepres ent.

(3) Coils and con denser s. Check coils and co ndense rs for properfunctioning.

(4) Dis tributors. C lean distributors th orou ghly. Check the points

frequentl y a n d replace as nece ss ary. Pitted poin ts m ay keep the engines from startin g.

(5) Spark plugs. Tes t and replace spark plugs if necessary . If itis difficult to make the engines fire, re duce the ga p from 0.030 to 0.025inc h. T his will mak e sparking easier at the reduced vo ltage s likelyto preva il.

(6) Ignition t iming . S ee parag raph 73 for detaile d p rocedure.

(7) Batterie s. The efficiency of a battery drop s sharply with de

creasing tem peratures and becomes pra ctically ni l at — 40° F. Do nottry to sta rt th e engin es wit h th e battery whe n it has been ex po sed totemper atures below — 30° F. without first warming up batte ry. Besure that the battery is alway s fully c harged with the h ydrometerre ading betw een 1275 to 1300. A fully charged,b attery wi ll not fre ez eat tempera tures u sually encountered even in arctic cli m ates, but a dis-

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cha rged battery will freeze at 5° F. Do not add water to a batterywhen it has been exposed to subzero temperatures unless th e batteryis to be char ged immediately. If water is adde d and the battery is notput on charge, th e layer of water wil l stay at the top and freeze before it has a chance to mix w ith the acid.

(8) Before every start, be sure th ere is no ice or m oistureon the wiring or other electrical equipment.(9 ) An outlet is prov ided for ready connection of

a battery for charging th e vehicle batteries or su pplying additiona lcurrent for cranking (par . 83).

24. Cold Weath er Operat ionS T A R TI NG A N D O P E R AT I O N .(1)

(te) It is possible to start gasoline engines with batteries attemperat ures as low as —30° F. if th e engines are properly lubricated,in good mechanical condition, and the battery is fully charged. If thevehicle is equipped with a winte riza tion kit, always use the heater towa rm up the engines.

Prio r to attem pting a start, see that eve rything is in readinessso that the engine will s tart on the first trial. Try to avoid having theenginesfire a few times and then stop. W ater is one of the products ofgasoline combustion, and in a cold engine this w ater may form a frostand make it impossible to start without heati ng the engine to above3 2° F.

Start one engine at a time, with th e accelerator and hand throttlefully closed. This will set the auto matic choke correctly. N o further ch oking is possibleor necessary. St art one engine with another (par.14) if battery capacity is low.

Caution: Do not pu mp or depress the th rottle pedal swiftly to thefloor before starting the engine. This will force raw gasoline into the

cylinders , causing flooding, decrease oil film in the cyli nders andhi nder starti ng.

After the engines have starte d, set the hand throttle to allowthem to run at 800 to 900 revolutions per minute fo r 4 to 5 minutes,to allow the oil to warm up before opening the th rot tle further. Thisshould be done wi th the transm ission selector lever in n eutral. T henshift the selector lever to DRI V E and allow the engine to idle for several minu tes more to warm up th e oil in th e transmission . Do notdrive the vehicle over 5 miles per hour for at least 10 minutes afterstartin g, to permit the oil in the transfer un it and controlled diff er entialto warm up.

(2 ) Cover engines with tarpaulin,tent, o r portable shed. Place oil stoves,firepots,or four to five ordina rykerosene lanter ns un der the covering about 3 hours pr ior to the timethe start is to be made.

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(6) Keep the vehicle in shelte red ar eas, especially areas shelter edfrom wind. Cold winds increase start ing difficulties.

If the vehicle is equ ipped with a winterizati on kit, ke ep theheater operati ng and the covers closed wheneve r the engines are notoperating.

6. STOPPINGE N G IN E S . Increase engine speed ju st before turni ng offignitio n; then turn off ignition switches, releasi ng accelerator at thesame time. As the engine coasts to a stop, it will blow o ut all theresidual prod ucts of com bustion and leave only air and gaso lin e vaporsin the engine.

INSPECTIO N. Inspect the vehicle frequently. Shock resis tanceof metals, or resistance against br eaking, is greatly reduced at extremely low temperatures. Opera tion of vehi cles on hard, frozeng round causes strain and jo lting which w ill re sult in screws breakingor nuts jarring loose.

25. Operatio n U n d e rDusty C o n d it ionsGENE R AL. When ope iating under dusty or sandy con ditions,

special precautions m ust be taken to prevent excessive wear a nd damage to the m oving parts of the power unit and suspension system.

A IR CLEANERSA N D BREATHERS. Under extremely dusty cond itions, the air-c leaner oil reserv o irs must be cleaned every 2 to 4 ho urs,

or more frequentl y as required. Air-cleaner elemen st must be clean edwhen in spection reveals that any appreciable qu antity of dirt hasaccu mulated to restrict the free flow of air or th eir capacity to trapthe dust has been reached. Continu ed operatio n of the engine withdirty or sa turated air cle aners will cause damage to the eng ine whichwill contin ue and increase long aft er the air cl eaners have been cleaned.The final drive breathers must be cleaned m ore freq uently as requiredwhen o perating under dusty conditions to prevent premature w ear

and da mage to these units. The engin e oil filter will be cle anedmore frequently as requir e d to maintain its efficiency. C arefullyexamine all lubricating o il bayonet gages fo r evi dence of grittysubstance th at would indica te the oil has become contaminated andm ust be changed.

C O O L I N G S Y S T E M . Inspect radiators and oil coolers frequentlyto make sure ai r passages are no t restricted by accumulation of dir t.Clean the radiator cores by flushin g with water under p ressure or blowout with compressed air.

CAREO F T R A C KSUSPENSIO N SYSTEMU N D E RD U S T YC O N D ITIONS.Lubricate track-suspen sion system more frequent ly to cleanse th e bearings of any sand or dirt that may have worked into the hubs orhousings. Inspect track- suspensio n system units inc luding track link sfor evidence of pre mat ure wear. Remove worn units promptly andinstall new ones to prevent ultimate fail ure.

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26. SubmersionG E N E R A L .If a vehicle has been submerged in wa ter, p articularly

salt water, the problem of arresting ru st and corrosion calls for immed iate action, if the tactical situation p ermits .

STOPPIN G R U S T A N D CO R R O S I O NA FTER S U B ME R S I O N .Remove

water from every pa rt of the vehicle and dry all exposed parts with cloths an d compressed air. If the suspension system has been submerged for even a few minutes, lubri cate all suspension points to cleanse the bearings of w a ter and grit. Coat all part s accessible, insidean d out, with preser va tive lubricating oil. If pre servativ e compoundsare not available im mediately, use ordinary engine oil temporarilyu ntil preservative compounds canbe obtained. In an emergency, leave vehicle submerged to keep air fro m wet metal part s unt il prese rvati vecompounds can be secured. In the case of assemblieswhich have to bedisassembled and dried, perfo rm these operatio ns as soon as the tacticalsituation permits.

PE R M A N E N TP R O TE C T I O N. Regard less of th e temp ora ry steps tak en as outlined in subparagrap h & above, the vehicle must be deli vered at th e earliest possible moment to highe r echelons for disassembly, cleani ng, repair, and p ermanent protecti on. The higher echelonsmu st pa y particular atten tion to possible da mage caused by the sudden cooling of parts of the engin e or tr ansmissi on whi ch were at operatin g

tem perature s at the time of submersion. If submerged in salt waterfor any length of time, aluminum or m agnesium p a rts will prob ably beunfit for furt her use and must be replaced.

Section X. DEMOLITIO N TO PREVENT E N E MY USE

27. Gen eralDestruc tion of the vehicle, when subject to cap ture or abandon

ment in the combat zone, will be u nde rtaken by the us ing arm onlywhen, in the judgm ent of th e milita ry command er concerned, suchactio n is necessary.

The instructions which follow a re for in form ation only . Certainof the methods of destruction outlined require TNT and i ncend iarygr enades w h ich may not be n ormal items of issue. The issue of thesem aterials, and th e condit ions unde r which destruc ti on will be effected,are command decisions in each case, according to the tactica l situati on.

If destr uctio n is resorted to, the vehicle must be so badly damage dthat it cannot be restored to a usable cond ition in the combat zoneeither by repair or cann ibaliza tion. Ade quate destru ction requires that all parts essential to the oper ation of the vehicle be destroy ed o rdam aged beyond repa ir. Equally im p ortant, the same essential partsmust be des troy ed on all like vehicles so that th e enemy ca nnot co nstr uctone complete opera ting unit from several partially da maged ones.

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28. Detailed In structionsD E ST RU C T I O NO F SIGHTINGA ND FIRE-CONTROLEQUIPMEN T . All

fire-controlequ ipm ent, including optical sights and binoculars, is difficult to replace. It should be the last equipment to be destroyed, if th e reis any chance personnel being able to evacuate. If evac uation of

personnel is made, all possible items of fir e-control equip m ent mustbe destroyed. Thor oughly burn firin g tables, tra jecto ry charts, sliderules, and similar items. Thoroughly smash all optical equipment.

6. D E ST R U C T I O Nor 155-M M H O W I T Z ER . (1) Fo u r methods of destroying the ho witzer are outlined below in their order ofeffectiveness. These instructi ons apply to the howitzer only. Toeffect demoliti on of the entire h owitzer motor car riage, destru ction asou tlined in this sub parag raph must be accomplished in con jun ctionwi th destruc tion of th e vehicle itself (subpar. below) and the sighting and fire-control equipmen t (subpar. above).

(2 ) O pen dra in plug on recoil mechanism,allowin g recoil fluid to dra in. It is no t necessary to wait for t he recoilfluid to d rain completely before firing the cannon in step below.

Caution: F iring the cannon with drai ned recoil mechanism withoutproceeding with steps (&) and below is n ot a sa tisfa ctory metho d of destr uction.

(&) Place an armed (safet y pin removed) a ntitan k g renade M9A1,

HE, or armed (safety pin removed) a ntitank rocket M 6 in the tube w ith the nose end to w ard the rear. T he grenade or rocket must becentered in the tube, using a wooden adapter. A n alternate for th ewooden adapter is the use of waste.

Ins ert an unfuze d HE complete round o r HE shell with propelling charg e into the cannon and close th e breech. Base- detonatin gH E shell cannot be used in this method.

F ire th e cannon, using a lanyard at lea st 100 fe et long. Theperson firing should be unde r cover to th e rea r of th e piece and approxim ately 20° off the line of fire. Elapsed time : Approximate ly 2to 3 minutes.

T he danger zone is approxim ately 500 yards.(3) Insert T NT blocks in the bore, near the

muzzle, and in the cham ber of the cannon. Close the breechblock asfar as possible without d am aging t he safety fuse. Plug the muzzletightly with eart h to a distance of approxima tely 3 calibers from muz zle. Detona te the TNT charges simultaneously. Th irty to fifty

half -pound blocks will be needed for effective demolition. If it isnot possible to plug the bore , a larger numb er of TNT blocks will beneeded or effective demolition.

(i) Bam an HE shell (wi thout base fuze) int o the f orcing cone andplace TN T blocks behin d it, as specified above. Close the breechblockand detonate t he TNT charge. A sufficient len gth of sa fety fuse

4 3

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should be used to permit personnel to reach safet y zone or cover. Thefuse may be routed through the pr imer hole in the spindle.

Attention is invited to the fact that, for the larg er calibers, thenumber of blocks to be used is an estimate not proved by tests.

(4 ) Plac e unfuzed incen d iary g renades M 14 on

their sides, one on top of another, in th e chamber. Close the breech.Equi p another incendiary grenade with a 15-second safety fuse, ignite,and toss it in the muzzle. Quick ly elevate the cannon to its maximum elevation. Elapse d time: 3 to 5 minutes. Six to eight grenades percannon are required.

The metal from the gren ades will fuse with t he interior of t hebreechblock, making it impossible to open the breech.

(5 ) («) Fire adjacent cannons a t each other atpoint-blank range, using HE or AP shells. Two or more d irect hits

from a weapon of the same caliber, on a vital spot such as the breechmechanism, recoil mechanism, or tube, should adequa tely destroy theart illery piece. Fire fro m cover. Danger space is from 200 to 250yards.

(6 ) Destro y th e last weapon and carriage by the best means available.

Danger from cannibaliz ation is inherent in this method.(6) Instructions for demoli tion of ammunition are

contained in TM 9-1901.D E S T R U C T I O Nor V EHICLE. Three methods of destro yi ng the vehicle are outline d below in their order of effectiveness. These instructions apply to the vehicle only. To effect demolition of the entirehowitzer moto r carriage, destruc tion as outlined in this subparagraphmust be accomplished in con junction with destruction of the cannons,and sighting and fire-control equipm ent and above).

(1) Remove and empty portablefire extinguishe rs. Puncture the fuel tanks.

Pr epare a 3-pound and a 2-pound TNT charge, with tetryl nonelectri c caps and about 6 feet of sa fety fuse in each charge. Open theengine compa rtment and place the 3-pound char ge between the engines. Place t he 2-pound charge against left side of the transfer unit,as ne ar diffe rential as possible. Place a ^-po und charge of TNTagain st left fuel tank. U se only a cap (no fuse) in this charge. Pointthe cap end toward the 3-pound charge.

C aution: If cha rges are prepared b efo rehand and carried in the

vehicle, keep the

capsand

fuses separated from

the TNTcharges

un tilth ey are to be used.(c) If sufficient time and ma terials are available, prepare and place

a 2-pound TNT charge at th e center, of each track assembly.Ign ite the TN T charges and take co ver.

(2 ) Remove and emp ty portable

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fire extinguishers. Puncture the fuel tanks. Open all doors andhatches.

(6) Fire on the vehicle, using adj acent howitzer motor carriages ,tanks, an titank or other artillery, or antitank rockets or grenades.Aim at the engine com partm ent, suspension,and armament in th e order

named. If a good fire is started, the vehicle may be considereddestroyed.(c) Destr oy the last remaining vehicle by th e best means available.(3 ) Remove and e mpty portable fire

extingu ishers. Puncture th e fuel tanks.(6 ) Using an ax, pick, sledge, or any other heavy object, smash all

vita l elements, such as distr ibutors, carbur e tors, air cleaners, generators, spark plugs, lights, instrume nt s, and co ntrol levels. D estroy th erad io sets by shearing off all panel knobs, dials, and switches. Breaksockets, smash tubes, coils, microphones,earphones, and batter ies. Iftime permits and a sufficiently heavy object is available, smash theengine blocks, crankcases, and transmissions.

(c)Po ur spare gasoline or oil over the entir e vehicle and ignite.

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PART T HR E E

MAINTENANCE INSTRUCTIONS

Section XI. GENERAL29. Scope

Part T hree contain s inf orm ation for the guidanc e of the p ersonnelof the usi ng organi zations responsible for the maintena nce (crew andbattery) of th is equipment. It contains informa tion for the perfo rm ance o f the scheduled lubrication and p reventive main tenan ce services,as well as description an d mainte nance of the major systems and u nitsand the ir functio ns in re lation to o ther components of the equipment.

Section XII. ORGANIZATIONAL SPARE PARTS, TOOLS

AN D E QUIPMENT30. Organizat ional Spare Parts, Tools an d Equipment

SPA R EPA RTS. A set of organizatio n al spare parts is supplied to the using arm fo r field replacemen t of these parts m ost likely to become worn, bro ken or otherwi se unserviceable.

T O O L SAND E Q U I P M E N T.A set of or ganiz ational tools and equipment is supplied to the using arm for maintainin g and us ing th e ma terie l. This set con tains items requi red for disassembly , assembly,

cleaning and pr eserving the 155-mm. Howitzer M otor C arriage M 41.Tools and Equipment should not be used for purposes other than prescribed an d, when not in use, should be pro per ly stored in t he chestand /or provided for them.

LIS T O F S PA RE PA RT S ,T O O L S A N DE Q U I P M E NT. Spare pa rts, toolsand equip ment suppli ed for the 155-mm. Howitz er Motor Carria geM 41 are l isted in WD Cata log OED 7 SNL G-236 which is the authority for re quisitioning replacements.

31. Specially Designed Tools an d Equip m e n tCertain tools and equip ment listed in WD Cat alog ORD 7 SNL G - 2 3 6are specially designed for m aintenance, rep ai r and general use withthe 155-mm. Howitzer Mo tor Carriage M 4 1 . T hese tools and equipment are liste d below for in format ion only. This li st is not to be usedfor req uisitioning replacements.

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Item

A

bearing race rem

r.

_..

A

puller,slieham

r,tosio

bar and co

ensating link pin replacer.

BOLTeetransmssio lifing.-

CALEextensio rubber cored wth

f

eplug at both es,doble con

ducto,stranded No. 1 AG 20 fet ong.

F

UE, track o

t

and conecto

pulling.

GAEadjusting,rear,se

(use in

transmssios l-

and up).

GAGE, transmission, oil pressure_

H

DE

f

r

and replacers

(length or-ll 8% inches).

LIER, rack wheel, right and lein set-

LIER, vlv,rem

r and replacer...-.

PI, drif,bakp

PULER, e,shoka

PULER, slieham

r type,b

gud

geon.

R

VE

rleouter earing ace track

suppot.

REPLACER, bearing and se

track and

co

ensating wheel.

REPLACER, geretainer.

REPLACER, retainer,g

e(track sup

port roler).

Identifying No.

41-A-12-550, A7079201.

41-A-18-245, B7079311.

41-B-1586-300,

A266327,

K

J-1636-SA-5.

17-C-568, B257839...----..--.

41-F-2997-86, D78191- .....

41-G-12,

344920

, KM-S-1460-A.

41-G-446, B29887

5, KM-S-1467-

M6.

41-H-1397, A380406, TEC-4-223.

41-L-1400, A7079

701------------

41-L-1425, B226787 -----

41-P-596-300, B7

080501--

41-P-2907-196, A

7079316.

41-P-2957-33, C7

3615----

41-R-2373-120, B7080557-

41-R-2383-950,

B296108, B

D

T-70-103.

41-R-2390-450, B296095,

B

D

T-70-121.

41-R-2396-375, B7080461 -----

References

Fig.

137, 141

131

138

131

145

137, 141

140

134, 135

143

Par.

146, 147, 149

123

144

148

144

151

146, 147, 149

145, 148

145, 148

151

Use

Suspensio component re

placement.

Tansmssio replacement.

Track replacement.

Ue wth rem

rs and re-

placers.

Suspensio component re

placement.

Track replacement.

Shokabsorber replacemnt.

Suspensio co

oent replace

ment.

D D Do.

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00

Item

R

seal, t

s

rol.

SC

,remover, bearing, tr

e,

inch 12NF-2, length overall

inches.

SLNG,engine, lifting

.

.

.

-

SLNG,final drive, lifting

-

Identifying No.

4

A380369, B

T--2

4

-

A

7079203-

4

-

0,C707922 .

4

-

C7079301.

References

Fig. 1

4 6

126

Par.

151

67,68

141, 142

Use

Suspension c

petreplace

met

Use wit 41--373-20.

Eginer

et

Fnaldver

et

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33. Detailed Lubrication InstructionsLUBRICATIONE Q U I P M E N T.Each piece of materiel is supplied

with lubrication equipment adequate to maintain the materiel. Thisequipment will be cleaned both before and after use. "Lubricationguns will be operated carefully, and in such a manner as to insure a

proper distribution of the lubricant.

D R I V E NTOftUS M E M B E R FLYWHEELC O V E R

OIL PAN

FLYWHEELC O V E RDRAIN P L U G

"WATER DRAIN P L U G

OIL COOLER COVER^

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w,A. TRACK SUPPORT ROLLER B. TORSION ARM BEARING

C . TRACK W H E E L D. COMPENSATING W H E E LLINKAGE

E. GUNNER'S PLATFORMHINGE PIN

f. PLATFORM AND SPADEWINCH

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S ectio n XIV . P R E V E N TIVE MAINTENANCE SERVICE S

34 . General Information[ R E SP O N S IB I L I T Y A N D I N T E RVA L .Preven tive mainte nanc e services

as pr escri bed by A R 850-1 5 are a function of using orga nizat ion ma intenance personnel, and the ir perf orma nce is the responsibil it y of the commanders of such org aniza tions. These services consist gen erallyof Before-op eration, Du ring-o perati on, At-halt , After-o pe ration, and^Weekly Services pe rf ormed by the crew, and the scheduled services tobe perform ed at de sign ated interv als by batter y ma intenan ce personnel.

DEFINITIONO F TER M S . T he gen eral inspection of each item ap plies also to any supporting m ember or connection, and is gen erally acheck to see wh ether or not the item is in good cond ition, c orrectl y assembled, secure, or excessively worn.

(1 ) The inspec tion fo r "good con dition" is us ually an ex ter nal visualinspection to determ in e whether the unit is damaged beyond safe orserviceable limits . The te rm "good co ndition" is explaine d furth erby the following: no t bent or twisted , no t chafe d or burned, no t broken or cracked, not bare or fray ed, not dented or collapsed, not torn or cut,not det erior ated.

(2 ) The i nspect ion of a u n it to see that it is "corre c tly assem bled" isusu ally an external visual inspection to see whether it is in its nor mal

assembled positi on in the vehicle.(3 ) Th e inspection of a u ni t to determ ine if it is "secure" is us ually

an ex terna l visu al exa mina tion; a wrench, han d- feel, or a p ry-ba rcheck for looseness. Such an inspection must include any bracket s,lock washers, lock n ut s, lo cking wires, or cotte r pi ns used in assembly.

(4) "Excessively wo rn" will be und erstood to mean worn beyondserviceable lim its, or to a p o int likely to resu lt in failure if th e u nitis not re placed before the nex t scheduled inspection.

3 5. Crew Maintena n ceP U R P O SE. To ins ure mechanical efficiency, it is necessary that the

vehicle be system atic ally inspected at interv als each da y it is opera tedand weekly so defects may be discovered an d corrected bef ore th eyresult in serious damage or fa ilure. Ce rtain scheduled m ainte nanceservices will be perf ormed at these de si gnated int e rvals. Any defectsor unsatis factory op e rating chara c teristics beyond the scope of fir stechelon to co rrect must be reporte d at the ea rlie st oppo rtunity tothe d esignated individua l in autho rity. The services se t for th in paragrap hs 36, 37, 38, and 39, are those perform ed by the crew Befor e-operation , Dur ing- operati on, At- halt, and After-o p eration andW eekly.

U SE O F WA R D E PA RTME N T F O R M 48. D rive r preventi ve m aintenance services a re l isted on th e back of W a r Depart men t Form 48

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(Driver's Trip Ticket and Preventive Maintenance Service Record)to cover vehiclesof all types and models. Items pec uliar to th is vehicle but not listed on Form 48, are covere d in manual procedure sun der the items with which they are related. Certain items listed onthe form that do not pertain to this vehicle are eliminated from the

procedures as writ ten into the manu al. Every organiz ation mustthoroug hly train each driver in perform ing the maintenance proceduresset fo rth in this manual, whether, orno t they are listed specifically on Form 48. The items listed on Form 48 that apply to thisvehicleare expanded in this manual to provide specificpr ocedures foraccom plishment of the inspections and services. The services arearranged to facilitate inspection and conserve the time of the driver,and are not neces sarily in the same numerica l o rd er as shown onForm 48. The item numbers, however, are identical with those shownon that form.

36. Befo re-Ope ration ServicePURPOSE. Th is inspect ion schedule is designed primarily as a

check to see th at the vehicle has no t been damaged, tamper ed wi th, orsabotaged since the Af ter-operation Service was performed. Variouscombatcond itions may have rendered the vehicle unsafe for operationand it is the duty of the driv e r to determine whether or not th e vehicle is in conditi on to carry out any mission to which it ma y beassigned. This operation will not be entirely ommitted, even in extreme tactical si tuations.

J. P R O CE D U R E S .Before-ope ration Service consists of inspect ingitems listed below according to the pro cedure described, and correcting or reporting any deficiencies. Upon completion o f the service,resul ts should be reported promptly to the designated individual inauthority.

(1) Look over vehicle, equipm ent,and armament for damage which ma y have occurre d from fallingdeb ris, shellfire, sabotage, or collision since parking vehicle. Openengine compart ment and look for signs of tampering or sabotage, suchas loosenedor damaged accessories, loose fuel or oil lines, or disconnected throt tle linkage.

(2 ) Examine cylind er of fixed systemfor tight mo untings and closed valves. See that wire seal is intact.Look into engine compartme nt to examine extinguisher lines andnozzles for good conditio n and correct aiming. Be sure nozzles arenot clogged. Inspect portable extinguishe rs for good condition andsecurity. Make sure that wire seals are intact.

(3 ) -5 , Check amount of fu el in each fueltank and add where required. Check oil level in each engine. Add asmuch oil as necessary bring level to FU LL mark. Check level o f

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coolant in each radiator and add water if necessary. In freezingweather, be sure to add antifreeze compound of proper strength whenconsiderable water must be added.

Caution: Do not fill fuel tanks or radiators to overflowing. Leaveroom for expansion.

(4) Examine security of mountingsof all accessibleaccessoriesand of generator and fan drive belts on eachengine. S ee that fan and generator belts have %- to %-inch, finger-pressure deflection.

(5) Look under vehicle for any indicationsof fuel, oil, or water leaks. Inspect engine compartment for evidenceof leaks, particularly at engine oil pan, and at fuel and oil lines. Traceall leaks to their sources and correct or report them to proper authority.Close engine compartment.

(6) Start engines (par. 14). Observe ifchoke action is satisfactory. Note action of starter mechanism, particularly whether starter has adequate cranking speed. If low-oil-pressure warning light does not go out, engine should be stopped andtrouble corrected or reported to designated authority. Inspect handthrottle for free operation; return it to idling position and let engineidle while proceeding with the following Before-operation Service.

(7) The warning sig

nals for engines and transmissions should go on when ignition switchesare turned on, and should go out as soon as engines are started.

Observe both tachometers to see that they indicate approximate engine revolutions per minute, and that they registeraccumulating revolutions.

Observe engine temperature gagesto determine whether or not they are functioning. Engine temperature should increase gradually to operating range of 160° to 210 ° F.Maximum safe operating temperature is 240° F.

The ammeter should register zero or slight discharge(—) with the engines idling, or register zero or slight positive (+)charge with engines running at approximately 1,400 revolutions perminute. Any unusual drop or rise in reading should be investigated.A high-charge reading, for an extended period, may indicate a dangerously low battery or a faulty generator regulator.

(8) Test siren, unless tactical situation prohibits,for proper operation and tone.

(9) If tactical situationpermits, turn on all switches to determine that all lamps respond. S eethat lamps are secure and that lenses are clean and not broken.

(10) Inspect tracks, track wheels, support rollers,and sprockets for damage which may have occurred since last inspec-

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tion. Look for loose screws, impr oper track tensio n (par. 143), and lor any foreign matter in suspen sion linkage.

(11) Look for br oken, loose, ordamaged suspension arms, shocks, track wheels, compensati ng wheels,and linkage. S ee that track wheel, co mpensating wheel and support roll er bolts, nuts and cap screws are pr esent and secure.

(12) Inspect al l ste ering b rakelever linkage to de termi ne that it is in condition for safe ope ration.Pull back on bo th pa irs of stee ring levers (assistant driver's anddriver's) and observe whethe r or not both meet firm resistance at 6 to

.8 no tches of leve r travel. Check to d eterm ine that lever locki ng devices h old properly.

(13) Insp ect fe nders and san d shields to m akesure tha t they are in go od condition, secure, and do not in terfere w ithtracks.

(14)Test manual tra

vers ing and gun elevating con tr ols and operati on of firing contr ol s tobe sure that all mechanisms respond properly. In spect spade, wi nch, and platform and test for prope r operation. R eturn spade and platfor m to traveling position and make sure spade is properly secured.

(15) S ee that the four towing

shac kles a re in good condition and secure.(16) Ex amine decontam ination unit fortight mou nting , full charge, and closed valv e.

(17) M ake su re that tools,parts, and accessories belo nging to vehi cle are present, serviceab le, an dproperly mount ed or sto wed.

(18) Engines should idle smoothly at450 re volutions per minute. Accelerate engines several times afterthey hav e reached normal operating tempera ture (160° to 180° F.) andnote any unusual noises, or faulty operating characteristics.

(19) Driver must haveoperator's permit on his person . S ee that Accident-Report Form N o.26 , Lubrication Order, Ope rator's Manuals, and Form N o. 478, arepresent, legible , and safely stowed.

37. During -O peration ServiceO B S E R VAT I O N S .While th e ve hicle is in motion, listen for ra ttles,

kno cks, squea ls, or hums tha t may indicate troub le. Look for in dications of trouble in co oling system and for smoke from a ny part of thevehicle. Be on the alert to detect any odor of overheated componentsor units such as g enerato rs or brake s, vapo r from a leak in fuel system,exhaust gas, o r ot her signs of tro uble. Each time the brakes are used,

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or vehic le is turn ed, co nsider this a test a nd no tice any unsatis factor yor unus ual performa nce. Frequent checks of the instrumen t reading sare nece ssary. Notice promptly any unusual instr ument indication sthat may sig nify trouble in s ystem to which th e instrument appl ies.

P RO C E D U R E S .D urin g-operation Ser vice consists of observi ng

items liste d below accordin g to the pr ocedures fo llowing each ite mand investigat ing any indication s of serious trobule . M ake note ofminor deficiencies to be co rrected or repor te d at e arliest opp or tunity,usually at n ext schedule d ha lt.

(1) V ehicle should move straight w henleve rs are in releas ed position and l ev ers sh ould have a rea sonablyequal amount of travel and start to hold at appr oximat ely 6 to 8 no tches from releas ed position. Par king lever locks on driver's sideshould hol d lev ers securely in applied positio n.

(2) Vehicle shou ld start satis fact orilyfrom a s tandstill in either DRIVE or LOW range. B e on the alertfor abnorma l co nditions in trans missions as indic ated by excessive s lippage and engin e racing, unu sua lly severe shifting , o r shifting inwro ng speed ranges.

(3) Be on the alert for unusua l conditi ons in the tran sfer un it, such as hard sh ifti ng, gear clash , or jum pingo ut of g ear.

(4) Driver sh ould be on the a lertfor deficiencies in engine pe rform ance such as la ck o f us ual powe r, misfiring, u nusual noises, o r indications of overheati ng. O bservew h ether or not eng ines accele rate sa tisfactorily and c ontrols operatefree ly. If radio noise duri ng operation of the engine is rep orted,the drive r w ill cooperate with th e radio op erato r in locating the interf ere nce.

(5 ) O bserve readings of all in strumen tsfrequently durin g opera tion to see whether or not they are op erating prope rly to indicate o r recor d the prop er fun ction of the units towhi ch th ey apply. Also see if speedom ete r indicates vehicle speed inmile s per hour and re cords accumul ati ng mileage .

(6 ) Liste n for any unu sual noise from tra cks, suspens ion wheels, and rollers.

38. At-Halt ServiceIMPORTANCE. At-halt Service s may be regard ed as mi nimum

ma intenance proced ures and should be perf ormed und er all tacticalcon ditions, even though more ext ensive mainte nan ce services m ust beslighte d o r omitted altog ether.

P R O C E D UR E S . A t-ha lt Servi ce c onsists of investi gating any deficienciesnoted during o peration, in specting items listed below accor d-

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ing to the proce d ures follow in g the items, and co rre ctin g any de fic iencies found. Deficiencies no t corrected sh ould be re p ortedp rom ptl y to th e desi gnated indiv idu al in a uthori ty.

(1) Check fuel su ppl y to see th atit is adequat e to op erate vehicle to next refue li ng p oi nt. Check oil

level in engines and add oil if necessai'y. Check coo lan t sup p ly in each cooling system an d add clean w ate r as necessary. In free zingweath er, ant ifre eze of prop er s tre ngth should be added if considerable co olan t is needed.

Cau tio n: Be sure to ve n t press u re rad ia tor caps bef ore rem ov ing, to avoid serious injury from steam and hot water.

(2) P lace hand on each wheel and tr ack supp or t rol ler hu b to

determ ine wh et her o r not they are ab nor mal ly hot. If hubs are too hot to touch w ith the hand , beari ngs may be in adeq ua tely lu bric ated ,damaged , or im prope rly ad justed. E xam ine tr ansfe r case, d ifferenti al, and final dr ives fo r excessive hea t and leakage. Exam in e shockabsorbers, for heat; a cold shock abs orbe r is no t opera tin g.

(3) Look fo r broken, loose, or da m aged suspension ar ms, l inkage, shocks, track w heels, rollers, and compe ns ating wheels. In spect to determ ine if suspension wheel, com pensa ting wheelan d sup p ort roll er bolts, nuts, an d cap screws are p res ent and secure .

(4)~ Exam ine ste ering b ra ke li nkag e forda m age o r looseness an d inv estigate any irr eg ulari tie s no te d du ringo pera tio n.

(5 ) E xa min e trac k s and wheel tires to see tha tth ey a re secure, not damaged , and tha t tra ck ten si on is satis fa ctory (p ar. 144). Kemove stones and tr a sh from trac k s and suspensionsystem.

(6 ) Look aro un d and un de r vehicle and

in engine com pa rtm ent fo r in d icatio ns of fuel, oil, or coola nt leaks.(7) If op erat ing un der extremely dus ty o rsan dy conditions, in sp ect a ir cleaners at each ha lt, to see that they ar ein conditio n to de liver clean a ir proper ly. Service as requir ed.

(8) Ex ami ne fend ers an d sand shields to seeth at the y are secure an d in good condition.

(9) Ex ami ne tow ing shackles to seethat the y are securely fastened. Ex amine towing cable for fray ed orbroken co nd ition . Make sure that cable is m ounted securely when no t

in use.(10) Ins pec t hull o f vehicle fo r

damage. Ins pect camouflage net to see th at it is prope rly secured and n ot dam age d.

(11) Clean glass in vision devices and lights , andinspect for damage.

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39. After-Operation and Weekly ServicesPURPOSE. After-operation Service is particularly important be

cause at this time the driver inspects his vehicle to detect any deficiencies that may have developed, and corrects those he is permittedto handle. He should report promptly to the designated individual

in authority the results of his inspections. If this schedule is performed thoroughly, the vehicle should be ready to roll again on amoment's notice. The Before-operation Service, with a few exceptions, is then necessary only to ascertain whether or not the vehicleis in the same condition in which it was left, upon completion of theAfter-operation Service. The After-operation Service should neverbe entirely omitted, even in extreme tactical situations, but may bereduced to the bare fundamental services outlined for the At-haltService if necessary.

P R O C E D U R E S .When performing the After-operation Service, thedriver must remember and consider any irregularities noticed duringthe day, and in the Before-operation, During-operation, and At-haltServices. The After-operation Service consists of inspecting andservicing the following items. Those items of the After-operationService that are marked by an asterisk (*) require additional weeklyservices, the procedures for which are indicated in subparagraph (& )of each applicable item.

(1) Fill both fuel tanks. Check alllevel in engines and, if necessary, add oil to FULL mark on gage.Inspect level of coolant in both radiators and add as required, usingantifreeze compound in freezing weather. If oil or water use is excessive, investigate cause.

(2) 5 5 , Before stopping engine, accelerateand decelerate noting any unusual noise or irregular performance.Investigate any deficienciesnoted during operation.

(3) Inspect all instruments to see that theyare securely mounted, properly connected, and not damaged. Alsosee that they indicate or record the proper function of the units towhich they apply.

Caution: Be sure to vent pressure radiator caps before removing toavoid serious injury from steam and hot water.

(4) If tactical conditions permit, test siren operation and tone.

(5) Clean all vision devices and glass and inspectfor damage.(6) Clean all light lenses. Examine for broken

parts and security of mounting. If tactical situation permits, openand close all switches and see that all lights respond properly.

(7) Inspect fixed fire extinguisherfor tight mounting, damage, and leakage of valves or lines. Inspect

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nozzles for p roper aim, damage, and secu rity of m ou ntings and connections. Be sure wire seals ar e present and intact. Ins pect portab leextinguish er s for good cond ition an d security. S ee tha t w ire is present and intact. Be sure nozzles are not clogged.

(8 ) Inspect deco ntamin ator for full con

tent, dama ge, an d security o f m ounting . R emove fill er plug to checkcontents.(9 ) In spect batter y for damage or leakag e

and se curity of m ounting s an d connections. Top o f batter y, cables,term inals , and vent caps must be clean.

(5 ) A dd distill ed w ater as necessary to b ring elec trolytelevel on e-half inch above to p of plates. If dis tilled wa ter is not av ailable, any clean water is preferabl e to allowin g cells to ru n dry.

In low te mpera tures, do not add water un til vehic le is about to be oper ated. Clean and ti gh ten terminals if loose or d irty, and give them a light coating of greas e.

(10) Open engine compa rtmen tdo or an d in spect all accessible accessories for looseness and damage.Be sure fan an d generator belts are in good condi ti on and be lt ten sionis %- to % -i nch, finge r- pressure deflectionbetween pulleys.

(11) Examin e all accessiblew iringcondu its to see that they a re prope rly connected an d supporte d to hull.

(J) Tigh ten all radio noise suppres sor bond st raps andaccessible capa citor m ount ings and connections, an d be sure su ppressoruni ts are secure.

(12) Inspe ct c arburetor air cleaners and cran kcas e vent ilator air cleaners fo r good conditi on and security o f m o untings. Inspec t cond ition of oil and filter element.Clean and service if excessive dirt is p resent ac cording to lubri cationorder (par . 33 ).

(13) In spect accelerator a nd handthrot tle contro ls fo r se curity, damage, excessive wear, an d free oper ation.

(14) Exa m ine tracks for damage, excessivelooseness, broken or m is sing connectors. Insp ect track te n sion (par. 143). Adjus t if necessary .

(15) (a) Inspect suspension a rm s and com pensatin g linkage fo r looseness or damage. Eemove any fore ig nobjects embedded in the track s or between the wheels, sprockets, and

suspension arms. Examin e ru bber ti res fo r cuts, breaks, or separa tionfrom wheels. Be sure shock absorbers are secure an d not leak ing.

(5) Tight en suspension assembly bolts, cap screws, andn uts and see th at all sec u ring wires or cott er pi ns are pres e nt and ingood conditio n. Inspect guides, supp ort rollers, co mpensatin g wheels,and sprockets for excessive wear or damage.

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(16) Inspect brake levers for secu remounting, and li nkage for excessive wear or damage and for freeo per ation and secure holding of loc king pawls. Investigate or reportany deficiencies noticed during op eration.

(17) Examin e area beneat h vehicle an d floor o f

driving an d engine compartments for oil, fu el , or coolant leakage.(18) Check level of oil in tran smissions,transfer u nit and fina l drive housings and fill to proper level. Reportany abnormal usage.

Caution: In checking transmission level, be sure to use corr ectproce dure (par. 3 3 ).

Examine fenders and dust shields to se ethat they are in good co ndition and secure.

(20) E xamine th e four towing shackle s and pintle hooks to see that they ar e presen t, in good condi tion, andsecu rely attached.

(21) Exam ine entire hull for damage from sh ellfireor col lisio n. Inspect doors over d riving compartment for good condition and proper ope ration of hinges and latches.

(22) Inspect the peris cope prisms andwin dows to see that they are in good cond ition, clean, secure in theholders, and tha t the holders are securely mounted. Inspect the spareperisc ope and their storage boxes to see that th ey are in good condition, clean, and secure.

Caution: Periscop es shou ld be clea ned with a soft c loth or brushon ly.

(23)B e sure that howitzer is sec ure in mou nt, clea n, lightly oiled, and incon dition for immediate use. Test m anual howitzer elevating mech

anisms and firing controls for proper operation. C heck level of oilin ele vatin g ge ar case. Be sure all expo sed wiring is secure and undama ge d. Examine packing glands, oil li nes, piston and cylinderassembly, and dr ain plugs fo r leaks. Determine if m anual traversingand electric and manual elevating mechanisms are in good conditionan d ope rate satisfactorily. Inspect winch and test for operation . Deter mine if cable is in good condition. Inspe ct spade and pl atform.Chec k hinges and fasteni ngs. Determi ne if spade and platform arein g ood cond ition and operate satisfac torily.

(24) Tigh ten all items which re quire tightening as indicated by inspec tion.

Tighten the following: G un m ounting attachments,tools and eq uipment mounted on vehicl e, amm unition cases, or any other units which re quire tig hten ing on a weekly or mileage basis asindicated b y inspection or experience.

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(25) Lubricate all po intswhich veh icle lubricat io n o rder indica tes are necessary on a weekly ormileage b asis, or an y p oints which need addi tional lubrication as indicat ed by condition and ex p erience.

(2 6) Remove a ll empty shell cases and

refu se from gun mou nt. Clean all oil fr om driving com pa rtment andfloor of vehi cle. Rem ove excessive mu d and dirt from tracks and suspension syste m. S ee tha t gri lles are not obstru ct ed. Op en bulk headd oors and clean rad iator core air pass ages, if necessar y .

Wash exterio r of vehic le and remo ve all dirt and mud.If washing is imprac ticable , wipe as clean as possible and w atch forbright sp ots that would ca use glare. Wipe ou t all excess di rt, fuel,oil, or co olant drippings fr om engine compa rtme nt.

(2 7) S ee that tools and eq uipment assig ned to vehicle are present, in good condition, and pr operlyst ow ed, or mounted.

(5) C lean all too ls and equipment . S ee that tools andequip ment a re in servicea ble condition and th at to ols with cu tti ngedg es are sharp and proper ly protecte d. Pr operly mount or s towall items.

40. Battery Maintenan c e (Second Echelon )

F R E Q U EN CY . The frequen cy o f the preventiv e main tenance ser vices outlin ed herein is consi dered a minimum requirem ent for nor maloperation of vehic le. Und er unusual oper ating condition s such asextrem e tem per atures, dust or sa nd, or extremely wet terrain, it ma ybe ne cessary to perform certain mainten ance services mor e freq uently.

F I R S TE C H E L O NPA RT I C I PAT IO N . The dr ivers sh ou ld accom panythe ir ve hicles and assist the mechan ic s while pe riodic second echelonpr eventive m ainten ance servic es are p erformed. Ordinarily the d rive rshould pres ent the vehicle for a scheduled p rev entive mainte nanceserv ice in a reaso nabl y clean condition ; that is , it shoul d be d ry andnot caked with m ud or grease to such an extent that inspection andser vicing will be se riously hampered. However, the v ehicles shouldnot be w ashed or wiped thoroughly clea n, since certain types ofdefects, such as crack s, le aks, and loose or shifted par ts or assem bliesar e mo re evide nt if the surfaces are sligh tly soiled or dust y.

If in stru ctions other tha n those con tained in the gene ral procedu res in s tep (d) or the specific procedures in step (i) which follo w

a re re quired for th e correct perform anc e of a prevent ive ma intenanceservice or for cor rection of a deficiency, othe r secti on s o f this manual pertai ning to the item involved , or a de signated ind ividual inau thority, shoul d be consul ted.

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G E N ER A L P R O C E D U R E S .T hese general procedures ar e basic instruct ions which are to be followed when performing the ser v ices onthe items listed in the specific proce d ures.

The battery maintenance personnel must be thoroughly trained in theseprocedures so that they w ill apply them a utomatically.

(1) Wh en new or rebuilt subassemblies are installed to correct deficiencies, care sh ould be taken to see that they ar e clean, correctlyinstalled, properly lubricated, and adjusted.

(2) Whe n installing new lu bricant retaine r seals, a coating of thelubrica n t should be wiped over the sealin g surface of the lip of theseal. When th e new seal is a leather seal, it should be soake d in warmengine oil (OE 10) if practi cable for at least 3 0 minutes. The n, theleather lip should be worked car efu lly by hand before installing the

seal. T he lip m ust not be scr atched or marred. C aution must be exercised to in sure inst al lation of lip of seal in proper di rection.DEFINITIONO F T E R M S . Refer to par agraph 34&.

/. SPECIALSERVICES. These are indi cated by repeating the itemnumbers in the columns which show the interval at which the serv icesare to be performed, a nd show that the parts or assemblies a re to receive certain mandatory services. For example, an item num ber inone or both columns opposite a "Tigh ten" procedure m eans that theactual tightening of the o bject m u st be performed. The special services include the following:

(1) Make all nec essa ry adjustments in accordance withthe pertinent section of this manu al, special bulletins, or other curren tdire ct ives.

(2) Clean units of the vehicle with dry-cleaning solventto remove excess lubrica nt, dirt, and other for eign matter. After theparts are cleane d, rinse them in clean solvent and dr y them tho roughly.Take care to keep the parts clean until reas sembled an d be certain to

keep dry-c lea ning solvent away from ru bber or o ther material whichit wi ll damage . Clean the protective grease-coa ting from new partssince this material is usually not a good lubricant.

(3 ) This applies eit her to lubrication operations that do not appear on the ve hicle-lubricati on order or to itemsthat do not appear on such ord ers, b ut w hich should be perfo rmed inconne ction with th e maintenance opera tions if parts have to be disassembled for inspection or service.

(4 ) This us ually consists of perform ing special operations,such as replenish ing battery water, draining, and r efilling units withoil and c hanging or cleaning the oil filter, a ir cleaner, or cartridges.

(5) All tight ening operations sho uld be performed withsufficient wrench torque (-force on the wrench hand le) to tigh ten the

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unit according to good mechanical practice. Use a tor que-ind icatingwrench where specified. D o not overtighten, as this may strip threadsor cause distortion. Tightening will always be understood to includethe corr ect installation of lock washers, lock nuts, lock wire, or cotterpins prov ided to secure the tighten ing.

SPECIALC O N D I T I O N S . When conditions make it difficult to perfo rm the complete preventive maintenance proced ure at one time, theycan sometimes be handled in sections, pla nning to complete all o perations within the week if possible. All availa ble time a t halts and inbivouc areas must be utilized, if necessary, to as sure th at maintenanceo perations are completed. When limited by the tactical situation,items with Spe cial Services in the columns sho uld be given firstconsiderat ion.

W O R KSHEET. The numbers of the prevent ive maintenance procedures that follow are identic al with those outlined on WD AGOForm N o. 462, which is the "Preven tive M aintenance Service WorkSheet for Full-track and Tank-like Wheeled Vehicles." Certai n itemson the work sheet that do not app ly to this vehicle are not included in the procedures in the ma nual. In general, the nu merical sequence ofitems on the work sheet is followed in the manual procedures, but insome instances the re is deviation for conservatio n of the mechanic's time and effort.

SPECIFICP R O CE D U R E S .The procedures for perfo rming each itemin the semimont hly and mon thly mai ntenance p roc edures whichevershall occur first, are described in the following road-test chart. «Eachpage of the chart has tw o columns at its left edge correspon ding tothe monthly and the semimonthly m aintenance respectively. S eeWD Circular N o. 3 6. Very often it will be found that a parti cularprocedure does not apply to both scheduled maintenances. In orderto determine which procedure to follow, look down the column correspondi ng to the m aintenance due and w herever an item numberappears, p erform th e op eration indicated opp osite the number.

Thos e procedures preceded by an asterisk (*) require addi tionalservices at each third monthly service.

ROAD TEST

Those procedures prec e ded by an asterisk (*) require add itionalroad test, perform items 2, 3 , 5, 9, 12 , 13 , and 15 which requirelittle or no movement of the vehicle. When a road test is possible, it should be fo r preferably 3 and not over 5 miles.

Before-Ope r ation Service1 1 Perform the Before-operatio n Service outlined in

paragraph 3 6.

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ROAD TEST—Co nt inued

In s t r u m en ts an d Ga g esObserve readi ngs of al l instrum ents freq uently d ur

ing oper atio n to see wh eth er th ey are indica tin gpr o perly.

OIL-PRESSU R E WA RNIN G SIGN A L . In case of lighting of oil-pressure wa rning sig na l, vehicle should besto pped immediately an d trou ble corre c ted or re ported to pro p er autho rity.

EN GIN ET E M P E R AT UR E G A G ES . En gi ne temp eraturesshould rise gr adually to n orma l range , 160° to 210° F.,and gage shou ld always indica te below 240° F. If

gage ind icate s more than this , or if w arni ng signallights , stop vehicle unt il correction can be made.

A M METER. T he ammeter will reg ister zero or s lig htdischarg e (—) w ith the engines id ling, o r registe rzero or s li ght positive charg e (+) w ith engines runn ing at o pera ting speeds. Any un usual d rop or risein readi ng for an extended perio d may indicat e adan g erously low ba ttery or a faul ty gene ratorregula to r.

T A C H O M ET E R S . T achomete rs should indic ate engine speed an d acc umulat in g revol u tions w it houtexcessive noise or fluctuation.

S PE E D O ME TE R A N D O D O M E T ER . Speedometer shouldin dicate vehicle speed. Odometer should re g ister accu mula ting mileage w ithout excessive noise orfluctuation.

WA R N I NG L I G H T S. Tran smission oil pre ssu re warn

ing lights should be off when engines are ru nningfas ter th an 450 revolution s per m in ute. L ights mayflicker at slow idle speed.

Wi nd shield , Wi n d sh ield Wipe r s , and SirenInspec t w indshie ld assembly and w ipers (when in

use) to see that the y are in good co ndition, secure, an d w he ther or not wiper blades move thro ug h the ir fulls troke an d contac t sur face evenly. Insp ect siren fo rgood cond ition and secure moun ting and, if tactic alsituatio n perm it s, te st fo r o perat ion and tone.

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ROAD TEST—Cont inued

Brakes (Steer ing)With vehicle sto pped, pull back on steering brake

levers; if brakes are pro perly adjusted, levers shouldstart to take hold at 6 to 8 notches of travel on ratchet.Accelerate vehicle to a moderate speed, release accele rator, apply both steering brakes, and observewhetheror n ot they stop the vehicle effectively. A pply steering brakes independently, a nd see that they steer vehicle properl y . Apply parking brake with vehicle onreasonable incline. It should h ol d vehicle effectively,and locking device should hold levers in applied

position.

Transmiss ion (LeverA c t i o n ,Vibrat ion, an d Noise )O perate vehicle through each speed range of trans

mission. Observe whet her or not selector lever operates properJy and whether or n ot there are any unusualvibrations or noises in any speed range th at mightindicate damage, excessive wear, loose mountings, orimproper operation.

Eng ine (Idle, Acce le ra t ion, Power, No i se , S m o k e ,an d Oil C o n s u m p t i o n )

IDL E . With the vehicle stopped, observe if enginesrun smoothly at normal idling speed, 450 revolutionsper minute. Throughout road test, observe if there isany tendency of engines to stall when accelerator isreleased and hand thr ottle closed.

A C C E L E R AT I O N, P O WE R ,VIBRATION,A N D N O I S E . Testengines for normal acceleration and pulling power ineach speed. While testing in d riving range, acceleratefrom low speed with wide-open throttle up to topspeed and lis ten for unusual engine noise,knock, whine,or v ibration that might indicate loose, damage d, excessivelyworn, or inadequately lubricated engine partsor accessories, or loose mountings or drive belts.

SMOKE. Du ring operation, observe if there is excessive smoke from exhaust.

OIL C O N S U M PT I O N . Upon completion of road test, acheck should be made to determine whether or noteither or both engines ha ve been consuming an excessive amount of oil.

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10 10 U NU S U A L NOISES (PR O P E LLERSHAFTS AN DUNIVERSALJO INTS, D IFF E R E NTIAL A N DFINA L DRIVES,SP R O C K ETS,W H E E LS, SUPPORTROLLERS, A N D T R A CKS) . Duri ng

ro ad test , li st en for any u nusual noise from the se units,indic atin g dama ged , d efect ive or loose parts, or in adequate lu bricat ion.

11 11 T E M PERATURES(TRANSMISSION,TRANSFE RU NIT, DIFFERENTIAL, AN D FINAL D RIVES, H UBS, SPRO C K ETS,W H E E L S, A N D SUPPO R T R O L L ER S). Aft e r operating ,rem ove bot tom inspec ti on plate and exami ne tran smissi on s for excessive heat. Check by ha nd-feel foran y abno rma l temper at ure in tra ns fer unit, differential an d fin al d riv es, hubs of sproc kets, wheels , and s upport roll ers .

loc ation on grade is se lecte d for th is check, ti m ewil l be saved in perf orming item 12.

12 12 G UN ELEVATING A N DTRAV E RSINGME C H ANISM. Pla ceve hicle in a position where it wi ll be tilted (sidewise) about 10°. Tra verse gun mount th ro ugh its full

rang e, by hand cont rols, ch ecking for indicat io n ofbind ing. With ho wi tzer pointed forw ard, elevate it

through its entire ran ge w ith ha nd controls ; check for bindi ng , excessive lash, or er ratic acti on .

13 13 L E A K S. Look in engi ne com pa rtment, and also benea th vehi cle, for ind ication s o f fuel, oil, or coola ntlea ks.

15 15 T R A C K TENSION; FINAL R OA D TEST. Inspect fo rsatisfa c tory tra ck tension af ter final ro ad test (pa r.143 ), and adju st if necessa ry.

MA IN TENANC E OPERATIONS

Engine Crankcase (Leaks an d L evel )17 17 O bserve bo th crankca ses fo r in dicat ions of oil leak s,

and inspec t bayonet gages for oil level. A dd oil asnecessary . If oil ch ang e is du e or con di tion of oil

warran ts a change , drain an d refill cr ank cases to prop er level with specified oil. See lubr ic ationorder, paragrap h 33.

oil is changed, do not s tart engin es until new oilfilter ele m ents have been instal led as in item 54.

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RO A D TEST—C o n t i n ued

54 54 ENGINE O IL FILTERS. Ins p ect oil filters to see th ai they are in good condition, secure, and not leaking.Drai n off accumulated sedime n t fr om filte r bowl.

54 C LEANA N D

SE R V E .Kemove oil filter elements, cleancases, and insta ll new fi lter elements,u sing new gas ketsand tightening covers securely . S ee lub rication ord er,parag rap h 32.

18 18 SID E A R M O R( F E ND E R S ,DUSTSHIELDS, GU A R D S ,PAIN TA N D MARKINGS, SH A C K L E S ,A ND SIREN ) . Inspe ct theseitems to see that they ar e in good co ndition, tha t arm or,fe nde rs, dust shields (if so eq uipped) , gu ar ds, shackles,and siren are secure an d that tow ing shackle s are notexcessively worn. Observe condition of pai nt for ru stor polished surf ac es that ma y cause reflections, an d (unlesscovered for ta cti cal reasons) see that al l vehiclemark ings are legible.

19 19 B O T T O M(AR M O R ,IN SPECTION PLATES, A N D DRAINPLU G S ). S ee th at these items are in good co nditionand secure, and th at bottom dr ain plug s are tig ht. T ig hten all b o ttom inspection plates securely.

20 20 DIFFERENTIALA ND F INA L D RIVE S . Insp ect housings for good condition an d le akage; check lubric ant level.S ee that all assembly and m ounti ng bolts are secure .If change of lubri can t is due, or conditio n o f oil warrants a change, dra in and refill wi th specified oil a tth is time. S ee lub rication ord er, paragra ph 32.

20 TIGHTEN. Tighte n all externa l assembly andmounting bolts securely .

21 21 T RAC K S (SHOES, S H O EPIN S , A N D BU S H I N G S ) . Inspect tra cks to see th at these items are in good condition, correctl y assembled, secure , and not excessivelyworn. T ighten tr ack screws to 80 to 90 foot-pound s.

*Note:

21. When ever the trac ks are disconnected an d removedfro m th e sprockets, suppo rt roller s, a n d wheels , or ateach thir d mo nthly mainten anc e service, the rel ated

items 22 and 25 marked on the Prev ent ive Mainte nanceService Wor k Sheet WD , AGO Fo rm 462 should beinspected as described below in the a sterisk-mar k ed (* )procedures. On the regular semimonth ly and month lymainte nanc e services, th e tracks should not be removedunless rep air s are needed.

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ROAD TEST—Continu edMAINT EN ANCE

Month ly Semimonth lyC aution: W heneve r tracks are rem oved for repair

or replac ement, do not reinstall t rac ks until the services fo llowed by the as te risk (*) in item s 22 and 25have been c omple ted.

22 22 COMPENSATING (W HEELS,A RMS, ADJUSTMENT,LOCKN T TTS). In spect the se items to see that they ar e ingood co ndition , c orrectly assembled, s ecur e, and thatgrease is no t leaking excessively from whee l b e aringseals. Be s ure ad justing n uts and adjusting locks a resecure. Tighten all assembly and moun tin g bolts and nuts securely.

*Note:22 In a ddition to the above, a t each th ird monthly

maint enanc e service or whe never the trac ks are removed, che ck th e comp ensating wheel hub bearings forlooseness or end play . Spin th e w hee ls and listen forany unu sual noise that m ight indicate a d amaged,excessively w orn, or inadequate ly lu brica ted bearin g.

23 23 BOG IE (ARMS,SHOCK A B S O R B E R S, L I N KS, BRACKETS).

Ex amine above com ponents to see i f they a re in goodconditio n, correctl y assembled, secu rely mounted, and not excessively worn. Inspect shock absorbers fo rleaks.

23 T IGH T E N. Dra w u p all susp ension unit assemblyo r mounting nut s or screws securel y.

24 24 WH E E LS (TIRES,SUPPORTROLLERS). Inspect whe elsand rol lers for good con dition, co rrect ass em bly, andsecure mountin g. Pay particular atte nti on to see thattire ru bber has not separate d from rim and that tiresare not cut, torn , or exce ssively worn . In spect forexcessive lubricant leaks fr om beari ngs.

24 T IGH T E N . Jack up track wheels and test bearingsfor looseness, ro ughn ess, and en d play . Spin wheelsan d listen for any unusual noise. Tig hten assemb ly and mo unting bo lts securely.

24 Whene ver the tra cks ar e re moved, the above ope ration

shoul d be perf orm ed before th e tra cks are reinstall ed.25 25 S P R O CK E T S (Huas, T E ET H , A N D N U T S ) . Ins pect

sp ro ckets for good condit ion, corre ct assembly, andsec urit y of mounting bol ts. Inspect sproc ket teeth forexcessive w ear, and shaft flan ge gask ets or oil sealsfor excessive leaking of lubrican t. If sp rocket te eth

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are excessively wor n, sproc kets should be replaced or reversed . Tighten assembly and mounting boltssecurel y.

25 Iii addi tion to th e above, at each third monthly o peration, or whenever the track is dis connected and removed fromthe sprocke t, check the sprocket tee th for exce ssive wear, se ethat sprocke ts are well se cured to hu bs and that the hub-to-final drive bolts are secure. Check the sprocket hub bearingsfor looseness and end play. After performing the above, reinst all the tracks and connect th em securely.

26 26 TRA CK T E N S I O N . Adjust track to s tandard ten sion(par. 143).

27 27 T O P A R M O R ,H U L L , D E C K , PA I NT A N D M ARKINGS,GRILLES,D O O R S ,LATCHES, A N D A N T EN N A MA ST. Inspect these items to see that they are in good conditio nand secure. See that do or hinges and latches operateproperly, are no t excessively worn , and ar e adequatelylubricated. B e sure grilles are not obstructed . Examine paint for rust spots or polished su rfaces thatmay cause reflections and, un less covered for tacticalreasons, see that vehicle markin gs a re legible.

28 28 CAPS A N DGASKETS(FUEL A X DR A D I ATOR ). Insp ectto see that fuel tank and radia tor caps and gas kets arein good condition, secure, an d not leaking.

3 0 E N G I N ER E M O VA L ( W H E NREQUIRED) .SERVE. Rem ove en gines on monthly mainten ance

service only if inspecti ons made in items 9, 10, 13 anda check of oil consumpt ion indicate a definite need.

3 0 3 0 CLEAN. Clean exterior of engine and dry thor

oughly, tak ing car e to keep d ry-cleaning solvent awa yfrom electrical wir ing, terminal boxes, and equipment.

In this and follow ing services (items 3 2 to 60), theprocedures should be followed in th e b est possible manner ifengines are not removed from vehicle.

32 SPARK P L U G S (G APS A N DDEPOSITS) . Remove andcle an spa rk plugs. Inspect i nsulators for cracks orbreaks and electrodes for excessive burning. Replaceunserviceable plugs with new or reconditioned plugs.Adju st elec trodes of a ll plugs to be inst alled to 0.030inch by bending ground e d electrodes. Be sure to ins tall new gas kets and do not ove rtighten plugs.

Perform item 3 3 before reins talling plugs. Inspectthe spark plug resistor-sup pressors for scorching and cracksand be sure all connections are secure.

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R O A D TEST—Cont in u e d

33 CO M P RESSIONTEST (RECO R D) . Whe n sp ark plugsare rem oved for perfor m ance o f item 32, test compression of each cy linder and record gage re adings on W D

AGO Form N o. 462. I f there is more tha n 10 poundsvariation betw een cylinders, report to desig n atedauthority.

34 34 G E N E R AT O R S A N DSTA R T E R S .Insp ect gene rators andstar te rs for good condi tion, security of m ounting, andsecure wiring con nection s. Eemove co m mutator inspection covers and examine co mmutator for go odconditi on. S ee that brus hes a re free in br ush holders,cle an an d not excessively w orn , that brush con nectionsare secure, and that wires a re not broken or chafing.C lean commutator end of units by bl owing out with compresse d air. Tighten mounting bo lts securely.Inspect g enerator armatur e brush capacitors to see th at th ey are in good c ondition and sec urely conne cted.

36 36 DISTRIBUTORS. Inspect distri buto r bodies a nd external attachmen ts and radio noise resi stor-suppres sors for good conditio n and secure mou ntings. Clean

ca ps, rotors, and seals , and inspec t fo r good conditionand corre ct assembly. Lo o k for cracks or burns .Inspect b reaker points for good co ndition, good aline-ment, and a 0.015-inch gap. I f the breaker plate as semblies are un serv iceably dirty, rem ove the distri butor, c lean in dry-c le aning solvent, dr y w ith compressed a ir, lubri cate the parts as specified below for them onthly mainten a nce service, and reinsta ll the dis tributors in cor rect position for t iming. When cle aning di stributors, remove wicks and lubri cation cup s,clean , and dry while r emoved and reinst all them onlyaft er the distributor assemblies are cle aned a nd blownd ry with compress ed air. I f the b reaker points a repitted, burn ed, o r worn to an un se rviceable conditio n ,ins tall a new set. If point s are b adly pitted, test conde nser connections for tightne ss, a nd if tight rep lacecondenser also. If points ar e slightl y pitted or b urned,

dress wit h point file or 2/ 0 flint p aper and blow offfilings with comp ressed air.SH AF T . Check sha ft s by han d-feel for looseness to

determine wh e ther or not the bu shings are wor n.C E N T R I FU G A L A DVA N C E . Test rang e of moveme nt

of cent rifuga l adva nce m echanism by rot ating sha ft

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RO AD TEST— Co n t i n u e d

and rotor by finger force. O bserve whet her or no tshaft re turns to o riginal position without bin ding.

36 SPECIAL L U B R IC AT I ON . Lubric a te cam surface s,

movable break er-arm pin and ca mshaft spari ngly wi thgener al-purpose grease, and the wick with a few drop sof engine oil (OE 10).

Keep lubricant off the d istributor points; do notapp ly m ore lubric an t than is specified ; and wipe the cam clea nbefore lubricating its surf ac e.

S ee lubrication order, pa ragraph 32.36 ADJUST. A djust b reaker-point gap to 0.015 inch at

wide-open position.38 38 IGNITION W I R I N GA N DC O ND U I T S .Inspect accessibleignit io n wiring and co nd uits for cleanliness, good condition, co rrect assembly, secure mounting , and see thatth ey are not chafing against ot her engine parts.

39 39 C O I L S . Inspect ignitio n coils and rad io noise suppres sor capa citors and be sure they are clean an d thatall m ountings and connections are secure.

42 42 BREATHER CAPSA N DV EN T I L AT O R S .Insp ect enginecrankcase ven tilato r oil bath air cleaner for good con dition and correct assembly. Clean oil bath air cleaner,reoi l an d reins tall securely. S ee lub ricat ion or der,parag raph 32.

43 43 A IR C L E AN E R S( C A R BU R E T O R S ) .D isassemble, clean,reoil, and reinstall car bure tor air cleaners followingcarefully the correct procedu re outli ned in lubri catio norder, paragr aph 32.

44 44 CA R B U R E T O R S(AU TO M ATIC CHOKES, T H R O T T L ES , L INK A G E). Inspect these items to see if th ey are ingood co ndition, correctly assembled, an d securely install ed tha t car buretors do n ot leak; that contr ol link age, automa tic choke, and throttle shaft s are n ot excessively worn. Inspect automatic chokes for closedposition when engine is cool. S ee that throttl e valvesopen fully when ac celerator is fully depressed. E e-move the fuel cleaner strainer from each carbure tor

fuel inlet, clean in dry clean in g solvent, and re ins tall.Tigh ten knurled nut fi nger-tight ; do not use pliers.

45 45 M AN I F O L D S( INTAKE A N D E XH A U S T). In spect accessible portions of manif olds fo r good condition ,secure mounting s, and for possible leaks.

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RO AD TEST— C o n tinued

45 T I G H TE N . T igh ten ma nifold assembly m oun tingnuts and cap screws to 25-30 foo t-pound s torque.

46 40 C Y LI N D ER (HEADSA N DGASKETS). Inspec t cylinder

heads for good cond ition and secure m ounting. N oteany indicat ions of oil , coolant, or compression leakage around cap screws or gaskets.

C au tion: Cylinder-h ead cap screws should not betigh tened unless there is a definite indication of looseness or leaks. If tight ening is necessary, a torque-indicating wrench mu st be used and screws ti ghtened in p roper sequence (fig. 51) to 70-7 5 foot

pounds.49 49 WA ' T E R P U M P S, FA N S , A N D S H R O U D S .Observe

whe ther or not these items are in good condi tion andsecurely mounted. B e sure fan blades do not in terf erewit h shr ouds or cores. See that the drive belts andpulleys ar e well a lined; belts not excessively worn,fra yed, oil soaked, im properly adjuste d, or bottomingin drive pulleys. Adjust to %- to 3^-inch finger-

pres sure deflection.51 51 EN G I N EC O M PA R TM E N T(BULKHEAD A N D C O N T R O LLINKAGE) . See that engine co mpartment incl udin gbu lkhead is in good condition , clean, and secure; andthat control li nkage in th e engine comp art ment is ingood condition, and securely connected and mounted.

51 C LE AN . Clean engine compartment as thoroughlyas possible. Wheneve r engines are removed, clean outall fuel a nd oil drippings, dirt, and refuse; wipe out the engine com partm ent w ith cloths soaked in d ryclean ing solvent, and dry thoro ughl y.

53 53 F U E L (TA N K SAN D L I N ES ). Inspect accessible portion of these items for co rrect assembly, good condi tion, and secure mounting. N ote whether or not there are indications of fuel leaks from tank s or lines. Drai nwater an d sediment from each tank by rem oving drain p lugs a nd allowing fuel to drain briefly u ntil it runs

clean. Tighten plug s and f uel tank drain-hole cover securely to p rev ent fuel and d ust leaks.

Caution: Catch drainings in container an d useevery precaution not to spill fuel. If fuel does spill,wipe up until dry before turning on th e main batte ryswitch.

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ROA D TEST—Cont inued

53 T IGH TE N . Tig hten accessible fuel line supp ort c lipssecurely.

56 56 OI L COO L E R S(TR A N S M I SSION A ND D IFFEREN T IAL).

E xamine diff erentia l oil cooler and lines, and tra nsm ission coo la nt lines for good condi tion, secure a tta chm en t and for leaks. Insp ect d ifferentia l oil cooler tosee that core is n ot clogged w ith dir t and tr a sh; cleanout foreign m aterial.

57 57 EX H A UST P IPE S AN D M U F FLERS. In sp ect theseitems for good con dition, secure assembly, and m ounting of exhaust pipes and mufflers and for indication so f exhaust leaks.

57 T I G HT E N. Ti ghte n all accessible mo unt ing bolts an d connections securely.

58 58 E N GINE MOUNTINGS. In spect all engine m o untingsan d radio bond straps to see th at they are in goodcon dition an d secure.

58 T IGH T E N. T igh ten all mounti n gs and b rack ets se curely. W hen engines are removed, tighten th em ount -to- engine and brac ket-to-hu ll bolts securely.

60 60 FIR E EXT IN G U I S HE R S Y ST E M (T AN K , VA L V E ,L IN E S , N OZ Z L E S ,AN D M OUNTINGS) . In spect cylinder an dvalve of fire extingu is her system for good co ndit ion,secure mount ing, and full charge. F ull ch arge may beobserved by presence of int ac t wire seal, but can be positi v ely dete rmi ned only by weighing. Exam in econtr ol cables to see that the y are in good con diti onand free to oper at e at a moment's notice. See that all lines and nozzles are in good condi tion, securelymo unte d and connected, with nozzles pr op erly aimedand no t clogged. If dirty or corr ode d nozzles ar efoun d, disconnect main feed line and blow out cautious ly with compressed air.

Empt y, or part ially empty, cyl inders sho uld be repo rted for r echarge or rep lacemen t im mediat ely .

C a ution: Do no t d ro p, st rike , or r oug hly han d leextin guish er cylinder, nor expose to excessive hea t.

SPECIAL L U B RIC AT I O N . Ap ply a few drop s o f oil topulleys and guides throu g h which control cablesoperate.

60 T IGH T E N. T ighte n all assembly and mountin g boltsan d screws.

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R OAD TEST—C o n t i n u edM A I NT E NA N C E

61 EN G I N E S ( INSTALL MOUNTING S, L I N E S A ND FITT INGS , W I R I N G , C ON T R O LLINKA G E A ND O IL SUPPLY).Re ins tall removed engines according to instruc ti ons in

paragra p h 68. Take care to tighten mo untin gs securely and to connect prop erly all fuel, oil, and coolantlines, wiring, and control lin ka ge which were disconnected when engine was removed. Adjust con tro llinkage. Be sure to refill engine crankcase with specified oil .

62 62 R A D I AT O RS (CORE, MOUNTINGS, H O SE, A N TIFREEZE,A N D R E C ORD S ) . Insp ec t these items for good condition, correct assembly, and for leaks. See that ra d iator mo unti ngs and hose and tub ing connections aresecure. Clean insects and refu se from ex ternal a irpassages of cores. Remove radiato r if necessary. T eststren gt h of antifre eze if in use. Ex ami ne coolant tode termine wh eth er or no t it is conta minate d wi th rust,oil, o r other for eign matter to the exte nt th at the cool ing system should be cleaned. If inspection in dicatesc lean ing is necessarj', proceed acco rd ing to par agraph

115, and curr e nt directiv es regardi n g proper proce dures, cleaner, neutra lizer and in hibitor. Refill radiator wit h pr oper coolant. Do no t fill to top b ut allowroom for expansion. On radi at ors which are removed,perfo rm th is inspection pa rtly while removed fr om the vehicle, and pa rtly after replacement, as necessaryto make the complete inspectio n p ro perly.

S ER V E . R ein stall all removed ra diato rs. T ake

care to tighten mo untings, an d hose o r tu bing connecti ons securely. Fill th e cooling system afte rward,add ing antifree ze or inh ib itor as requ ired and recheck the cooling system fo r leaks.

63 63 B AT T ER Y ( C A B L E S, H O L D - D O WN S,BAT T E RY C O M P AR T M ENT, R E C O R D or GR AV I TY , A ND V O LTAGE). In spectbatte ry case for cracks and leaks. Clean top of b atte ry. In spect cables, termin als , bolts, posts, strap s an dhold-downs fo r good condition. T est specific g ravityand voltage and record on W D AGO F orm 462. Specific g rav ity read in g below 1.225 indic ates batter y shoul d be recha rged or replaced. El ectrolyte levelshould be above top of pla tes a nd may extend one-ha lfinch above plates.

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R O A D TEST—C o n t in u edMAI NTENA NCE

63 S E RVE . Perf orm high rate disc harge test accordin gto instru ction s for "condition" test which accompany tes t instrume nt. Cell va ria tion should not be more

than 30 perc ent.Specific gravity m ust be above ] .225 to make this test .

63 63 C LEAN. Clean entire exter ior of batte ry and inte ri orof batt ery box. K epaint box if corroded. Ad d distilled w a ter to one- half inch above cell pl ates. Cleanba ttery te rmi nal, ter m inal bolts and nuts, a n d battery posts. Ins pe ct bolts for serv ic eability an d grea selightly. Tig hten te rmin als an d hol d-dow ns ca refull yto avoid damage to battery.

Close main battery switch and open fuel shut-offvalve at this time.

64 6 4 : A C C E L ER AT O R S(LIN K A GE A N D D UAL-THRO TTLE SYNC H R O NIZATION). See th at acc elerators and all ofthe ir co nnect ing lin kage are in good cond ition, and securely connected. P re ss the acc elera tors down fully to see wh ether or no t th e carb u retor throt tles open fu lly.

Check synchroniza tion of thro ttle linkag e at each ca rbure tor to see tha t throttle valves open and close together. A fter starti ng engines, test to see th at th rottles ar e so adjuste d tha t, at idle speed (450 rev olutionsper m inute). the variation between the two engines willbe no more tha n 50 revolutio n s per mi nu te and at 1,000revolution s per min ut e there will be no more varia tionthan 100 revolutions. Insp ect throttle co ntrol lin kage

to see tha t it is pr op erly adjuste d.64 A D JUST. Ad ju st throt tle con trol link age (par. 110).65 65 ST A R T I NG MO T O R SA ND INSTRUM ENTS. Star t en

gines, obse rving all startin g precaut ions out line d initem 1 . Note whethe r the gen era l action o f the st arters is sati sfactory , p articular ly wheth er or not the driv esengage, oper ate pr operly w ithout excessive noise, andhave adequate crank ing speed. Observe w hether each engine s ta rts readily . As soon as the engines start, observe whethe r or not al l ins trumen ts operate properly, and p articular ly if the oil pressure signal and amm eter indications are satisfa ctory .

67 67 IG NITIO NT IMIN G. With engine runni n g, determi n ewh ether or not ign ition timing of each engine is cor-

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RO A D T E S T — C o nt inued

rect , according to instruc tions (par. 73). Also obse rve whether or not automatic controls advance th espark as .engine is accelerated gradually. When nec

essary, adjust ignition timin g to specifi cations (par.73), taking care to see that distribu tor is well securedw hen adjustment is complete .

Ca ution: Be sure that distributor t iming is properly a djusted for efficient engine perfo rmance wit hgrade o f fu el being used.

6 8 6 8 REGULATOR U N I T(CONNECTIONS,VOLTAG E,CURRENT,A N D C U T-OU T) . S ee that regulator units and the

radio noise su ppression capacitors and b ond stra ps arein good condit ion, and that mountings and connec tionsare secure.

6 8 Con nect low-v oltage circ uit tester to regulator an dobserve whether or not voltage regulator, current regu lator, and cut-out control the generator o utput properly. Follow instructions in vehi cle manual, or tho sewhich accomp any test ins trument.

Caution:Ma ke test only after regulator h as

reach ed normal o p erating temperature.

69 6 9 E N G IN EIDLE. Ad just engine mixture and thro ttlestop to ob tain smoot h operation at 4 50 revol utions perminute. See paragraph 110.

70 70 THROTTLESYN C H R O N I ZATION. Depress acceleratorslowly an d observe whe the r or not tachometers of bothengines indicate within 50 revolu tions at 4 50 revolu

tions p er minute and within 100 revoluti ons at 1,000revolutions per minu te. At the conc lusion of thism aint enance service, allow engines t o cool properly byoperating at 450 revolutions per minute from 3 to 4minutes before stopping them .

71 71 G U N MO U N T (PAINT, SEATS, S T O W AG E BOXES, AMMUNITIONBOXES,CLIPS,A N DRACKS). Ins pe ct to seethat these items are in good condition, and securelyassembled and mounte d; that mount is clean, and that

paint is in satisfactory c ondition; that adjustingmechan ism of seats operate properly, a nd are adequately lubricated. Pay particular attention to see that shell hangers an d dividers are all present andpr operl y installed in ammunition boxes.

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R O A D TEST—Cont inuedM A I N TE N A N C E

73 73 PERISCOPES. Examine periscop e prism s an d windows to see that they are in good condition, clean,secure in holde rs, and that holde rs are securely

m ounted; that lever and lo cking devices ope rate fr eelyand are not excessively worn ; that their traversingan d elevating devices are free and not excessivelyworn. Examine spare periscopes and their st owag eboxes to see that they are in good conditi on, cle an, andsecure.

Caution: Prisms should be cle aned only with a softclo th or brush.

75 75 BRAKES (STEERINGLEVERS,LINKAGE,A ND SHAFTS).Inspect steering brake levers, linkage, and sh afts tosee that they are in goo d condition, securely mounted ,properly con nected, and not excessi vely worn. Applysteerin g brake levers and observe whethe r th ey beginto take hold at 6 to 8 notches of travel on ratchet.

75 TIGHTEN. Tighte n all assem bl y and mounting nutsand screws securely.

77 77 DIFFERENTIAL. Ex amine accessible part of the d iffere ntial case in driv er's compartm ent to see that it isin good condition, that all mounting and assemblyb olts and cap screws are secure, and that there a re no oil "leaks.

78 78 TRANSMISSIONS. Inspect transmissions to see thatthey are in g ood condition, secur ely moun te d, and notleaking. If conditi on or level of lubri cant indicatesnecessity for oil ch ange, drain and refill to corre ct levelwith specified oil. S ee lubric ation order, paragraph 3 2.

78 ADJUST. Adjust tran smission front band (paragraph 122).

79 79 TRANSFERU N I T (SEALS A N DLEAKS). Inspect thetransfer unit to see that it is in g ood condition, secu rely asse mbled, and mounted. No te whether oil isleaking from the case of seals. If co nditi on or level

of lubrican t indicates the necessity for oil change,drain and refill to correct level with specified oil. Seelub rication order, paragraph 3 2.

79 TIGHTEN . Tighten all external asse mbly andmo unting bolts and cap screws secur ely.

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ROAD TEST—Contin u edM AI N T E N A N C E

80 80 TR A N S MISSIONA ND TRA N S F E RU N I T C O N TR O L S A N D L I N K A GE. See that con trol levers and linka ge forthese units are in good condition, correct ly assembled,

and securely connected and mounted. See th at jointsare adequately lubricated and n ot excessively worn.81 81 PR O P E L L ER SHAFTS (UNIVERSALJOINTS, ALINEM ENT ,

- A N D Y OK E S). Inspect p rop eller shafts fo r good condition, corre ct and secure assembly. See tha t un iversal joints are not excessively worn and ins p ect for adequate lubr ication. L ook fo r excessive leaks a t seals of universal jo ints and at slidin g joint.

81 TI G H TE N . Tighte n all un iversal jo int assembly andyoke cap screws securely.

85 85 L I G H TS A ND SWITCHES (HEAD, TA I L ,B LA C K O UT , A N D

INTERNAL). If tactical situation pe rmits, test switchesand lam ps (lights) to see that they ope rate properl y.In spect all lights for good cond ition, secure mounting ,for broken lenses, and discolored reflectors.

86 86 WIRING (JUNCT I O N A N D TERMI N A L B L OC K S A N D

BOXES). Inspe ct to see that all exposed electrical wir

ing and con duits, termin al blocks, and boxes are in good condition, well supported, and securely con nected. Be sure radi o noise capa citors and/or wir ingsup port clip bonding s are in good cond ition, clean, andsecurely mounted or connected.

88 88 R A D I O B O N D I N G(S U P P R E S S O R S, FILTERS,C O N D E N S E R S, A ND SHIELDING). See th at all units no t covered in theforego ing specific procedure s are in good conditionand securely mounted an d connected. Be sure all ad dition al noise suppression bond str aps and intern al andex ternal toothed lock washers listed in paragr aph 106 are inspected for looseness or damage, and see th atconta ct surface s are clean. I f objectionable ra d ionoise from vehicle has been reported, make tests inaccordance with parag raph 48. If cleanin g and tightening of mo unti ngs and connections and replacement of defective radio noise suppression units does

not eliminate th e trouble, the radio operat or will repo rt the condition to the des ignated indivi dua l in autho rity.

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ARMAMENT

Howitzers : 155-mm. Howitzer (Mounts , Traversing, and Elevat ing Mechan i sm, Fir ing Cont rols)

126 126 Inspect to see that these items are in good condition,clean, well lubricated, correctly and securely assembled, and not excessively worn. Check to see that firing controls are in good condition and secure. Operatefiring controls to see that they function properly. Operate hand-elevating controls through entire range,

to see that they function properly. Traverse mountby hand to see if there is any binding, and that mountcan be turned through its entire range (17° left-21°right). Inspect electric elevating mechanism including motor, limit switch, wiring and operating controlswitch to see that they operate properly, are in goodcondition, correctly assembled, secure, and not excessively worn. Add oil to elevating gear case if required.

Make an operating check of power-elevating mechanism moving motor switch to either UP or DOWN orMANUAL position (fig. 1 7) to see if gun respondsproperly and any over-run is properly controlled.Tighten all assembly and mounting bolts and screwssecurely.

TOOLS AND EQUIPMENT

Tools (Vehicle K it and Pioneer)13 0 1 3 0 Check vehicle and pioneer tools to see that all items

are present, in good condition, and properly stowed ormounted. Any tools mounted on outside of vehicle,having bright or polished surfaces, should be paintedor otherwise treated to prevent glare or reflections.Tools with cutting edges should be sharp and edgesshould be protected.

13 1 13 1 E Q U I P M E N T. Check special equipment items against

vehicle stowage lists to see if they are all present, inserviceable condition, and properly stowed or mounted.

1 3 2 1 3 2 SPARETRACKBLOCKS. Inspect to see if they are allpresent, in good condition, and properly stowed ormounted.

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RO A D TEST—Cont inued

133 133 S PA R EOIL SUPPLY (RE COIL , H Y D RA ULIC, ENGINE). C heck to see that supply o f listed spare oil is presen tan d p rope rly stowe d. This supply should be mai n

tain ed at al l time s.134 134 DECONT AMINAT OR. E x amine d econtami nator to seethat it is in goo d conditi on , secu re, and fu lly charg ed .M ake lat te r check b y removi ng fille r plug.

T he solution must be renewed every 3 months as itdeteriora te s.

135 135 FIKE E X T INGUISHER (P OR T ABLE). Inspec t extingui sher to see if it is fully cha rged , in good con di tion,

secu rely m ounted , and if seal on v alve he ad is inta ct.Wei gh cylin d er to det ermi ne if it is ful ly charge d.

136 136 .PUBLICATIONS A N D FORM No. 26. Ch ec k to seewhe ther veh ic le man ua ls, Lu bricat ion O rder, Accide nt-Rep or t Form No. 26 an d F orm No. 478, MW Oand M aj or Uni t Assem bly Repl acement Record arepresen t, leg ible, and prop erly stow ed.

137 137 VEHICLE LUBRICATION. Perform a com pl ete lubri catio n servic e on the v ehicle ac cord ing to in struc tion s

in lubr ica tion o rder, par agr aph, 33, omitti ng only th oseite ms w hic h have received a ttenti on in the fo regoin gspecific pro cedu res. Replac e damag ed or m issingfit tings, lin es, or pl ugs.

138 138 MODIFICATIONS (MODIFICATION W ORK O R D E RS COMPLETED ) . Insp ect vehicle to det ermin e tha t all Modifications W ork O rders h ave been p roperl y com ple tedand ent e red on F o rm No. 478. En ter all m odific atio nsor

m ajor un it assemb ly replac ements m ad e at time ofth is service .139 139 FINAL R OAD T E ST . M ak e a fi nal road test, rech eck-

in g item s 2 to 15, in clusive. Rechec k transmis sion a nd di fferential to see th at lubr ic ant is at correc t level an dthat th e re are no leaks. Con fine this roa d test to th emi nim um distance ne cessar y to m ake satis fac toryob servation s . Whi le testing vehicl e, operate it in ano rmal man ner .

Correct or rep ort any deficiencies found d uring finalroad te st to designated authori ty.

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Section XV. TROUBLE SHOO TING

41. GeneralT h is section cont a ins trouble- shoo ting infor mation and tests

which can be made to help determin e the causes of some of the tr oubles that m ay develop in vehicles used under average climatic cond ition s(above 32° F.) . Each symptom of tro uble given under the ind ivi dualunit or system is followed by a list of possible causes of the trouble.The tests necessary to dete rmine which one of the possible causes isresponsible for the tr ouble are explained af te r each possible cause.

W hen trouble shooting, first turn to the subpa ragraph pertaining to the con dition at hand, and then perform the var ious tests i n theorder listed. T h is is important because the tests which are easiest top erform and co nditions m ost likely to occur are listed in the ir respective order .

4 2. E n g i n eS TA R T ER DO E SN OT C B A NK E N G I N E . (1 )

In order to complete th e starting c ircu it, th e emergencyignition switch and the regular ignition switch, as well as the ma sterbattery switch, must be O N. M ake sure th at all of these switches are turned on.

(2) T urn on lig hts. If lights donot ligh t, battery gr ound circuit is open or master switch is inoper ative. C heck gr oun d circuit and switch with test lam p or vo ltmeter(fig. 39).

(3) If lights go on p roperly,press starter butto n; then if lights go out, there is a poor connectionat the terminals, a t the batteries, a t the ground stra p, a t the master switch, or at the starter (fig. 37). These can b e . checked by a volt

meter between each successive terminal and ground. Clean andtig hten loose connections, replace broken g round strap s, o r replacedefective master switch.

wires in the vehic le are m ar ked at a ll connecti ng ends with thecircuit n umber, and these c ir cuit num bers appe ar in all of the wir ing di agramsin this sectio n.

(4 ) If lights dim cons id erably when s tar terbut ton is pressed, bu t still burn, batter ie s are low. Tes t batteries witha hydrome ter and a high-ra te discharge test er, if available. R eplaceany b attery units tha t do n ot test sa ti sfactorily.

(5 ) When the starte r button is first pressed, the starter relay circuit is ground ed th rough the transmission oil pre ssure warnin g signal switch (fig. 37). If light s donot dim at all, and tran smission war nin g light on the ins trument paneldoes not lig ht, the signal switch is p robably defective. A test can

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A

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readi ly be made by g rounding s ignal switch lead wire and this willpermit startin g the engine.

(6) If lights do n ot dim at all when star terbutton is press ed, no current is flowing to the st ar ter. If cause is no tin grou nd circ uit, use te st lamp to deter m ine if feed circ u it is complete

to re la y terminal; th en to solenoid coil, and finall y to st arter termi nal(fig. 37). R eplace relay lead, relay , solenoid , or ca b le as required.(7 ) If previ ous tests in dica te current to

starter te rmin al and starter does not turn, repla ce sta rter.E NG INE CRANKS Bur W I L L N O T STAR T . (1)

Check for w rong grade of engine oil. Che ck battery s tateo f char ge, connec tions, and groun d strap (sub par. above) . Chec kfor tigh t bea rin gs or tig ht pisto ns and rings. R eplace starter.

(2 ) Tu rn on fuel switc h.(3 ) Replen ish fuel supply.(4) A flooded co n dition may occu r after re

p eated cra nking. Usually one en gine starts and the ot her does n o t.11 flooded con d ition is suspect ed, hold accelera to r w ide open w hilestarting eng ines.

(5) Ope n engin e compart ment, remove ignit ion wire from one s p ark pl ug and ho ld terminal one- fourthin ch from cylin der head. Turn on ignitio n and crank eng ine. If

strong, blue-w hi te spark jum p s gap, ign ition is satisfactory. If nospark appear s or spark is weak o r red , pro ceed with tests in pa ragrap h 43.

(6)EN G I NE S TO P S . (1) Check ignition

wires an d connections fo r looseness or bre aks. Check bre ake r poi ntsto see that they are not stuck in the ope n position or no t opening dueto incorre ct gap adjustmen t. Tighten, rep air, or replace as necess ary.

(2) Check a ll fuel line s and connectio n sfor b reak s and clogg ing, a nd reconnect, cl ean, or repair as requir ed(p ar. 50). Clean g asoline filters an d screens.

E N G I N EO P E R ATES U N E V E N LY. (1)Check for inadequat e ignition (par. 43) .

(2) Check carbu retor adjustmen t and conditio n (par. 50).

(3) C hec k tachometers fo r differe nces

in engine speed and tune engines, or readj ust throttle linka ge as required (par. 110).(4) Listen for

air leak s and tes t for le aks by a pplying eng ine oi l (OE 10) to susp ected areas. T ighten or re place affec te d gaskets.

(5) Check compre ssion pressure. The compression pres sure at cra nkin g speed should be 102

92

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NO.14 NAT. RED &81. TR.(

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L. RED

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pounds or more. If the compression pressure at c ranking speed fallsbelow 95 pounds, notify highe r authority.

(6 ) Check compression pressure. If pressures vary considerably, or if all cylinders are low, notify higher authority .

E NGINE OV E R H E AT S .(1 ) Check level ofcoolant and fill to correct level with water or antifreeze. A lso check system thoroughty to determine cause of coolant loss (par. 49).

(2 ) T he belts drive the generator, waterpump, and fan. Inspect belts and, if necessary, adjust to obtain % -to % -inch slack measured as shown in figure 47.

Belts are matched in sets. If one belt is broken, all th ree belts mustbe replaced a t the same time.

(3) Open ventilating sliding doors onbulkhead (fig. 13). Check radi ato r core air passages to see if pluggedwith dirt, leaves, or twigs. Clean out. See th at inle t and outletgrilles on top of vehicle are not covered with tarpaulin or other equipment. Kemove screen from inlet grilleand clean.

(4 ) Check thoroughly asoutlined in para graph 49.

(5 ) Check and reset ignition timing (par.

73).(6) Ch eck oil supply a nd add to the co rrect

level.(7) Replace thermostat (pa r. 117).

/. E N G I N E O PE R AT ES NOISILY. (1)Check g rad e of gasoline us ed ; it sho uld be 80 octane. Check or

reset ignition timing ( par. 7 3). Remove cy lind er heads an d clea ncarbon (p ar. 60).

(2 ) Check oillevel; an overfille d crankcase w ill cause oil to foa m and va lve lift ersto become noisy. D rain oil to correc t level. Check co ndition s of cran k -case oil and cha nge oil if dir ty o r gritty .

(3) Ins pect fan, genera tor, distributor, a ndwater pump for unde rlubrica ted or frozen bea rings. Lu bricat e or replace uni t, as requir ed.

(4) C ranksh aft

or conn ecting rod bearin gs bur ned out. Notify ordn ance personnel.E N GIN E O IL PRESSURE Low (WARNING L I G H TSTAYS O N). (1)

Ch eck oil supply and ad d oil to the full mark on gage.(2) If oil le vel is hi gh (above the full ma rk), it ma y

be an indicatio n that the fuel p ump switch has been left on whi le theengin e has not been running and raw gasoli n e has pass ed th rough thecarburetor a n d manifolds an d into the cra nkc ase, caus ing oi l dilution

94

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and low oil pressure. Drain crankcase and install fresh oil (par. 33).Overfilling of crankcase should be avoided at all times.

(3) Check log book entries formileage of last oil change and grade of oil used. Eefill with correctgrade of engine oil.

(4) Inspect oil feed line from side ofcylinder block to valve lifter connection at center of vee, and replace ifcracked or broken. Replenish oil.

(5) If no cause of lowoil pressure can be found, the trouble may be in the oil pressure warning signal switch at the rear of the engine. Eeplace switch (par. 97).

(6) Remove oil filter inlet pipe at front ofcylinder block and install pressure gage. If pressure is below 12pounds with engine idling, notify ordnance personnel.

43. Igni t ion System

N o SPARK IN ON E CYLINDER.- (1)Make visual inspection of wiring to determine if disconnected, broken,or shorted. Reconnect, repair, or replace as required. Check currentto plug by cranking engine with wire disconnected and terminal atend of ceramic insulator held one-fourth inch from cylinder head.If no spark jumps, wiring is shorted or broken and must be replaced.

(2) If strong spark jumps with above test,fault is in plug. Remove plug and inspect for cracked insulator,broken electrodes, fouling, or incorrect gap. Clean, readjust, or replace as required.

N o SPARKT O A N Y CYLINDER. (1) Inspect distributor cap for loose mounting, moisture, dirt, or cracked orburned condition, and dry off, clean, or replace as necessary.

(2) Inspect high-tension wire and low-tension

wire from distributor to coil, and back through feed circuit (fig. 38).(3) Remove distributor cap and in

spect contact points for gap, burned condition, and spring tension.Service or replace in accordance with instructions (par. 70).

(4) Check coil and condenser withinstruments or by substitution, and replace one or both units asrequired.

44. Battery Circuit

N o CURRENTIN BATTERYCIRCUIT. (1)Close master battery switch.

(2) Inspect all cable connections at battery, apparatus box, and terminal blocks (fig. 3 9 ) and clean andtighten if necessary.

9 5

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(3) T u rn on lig h ts. C on nect aheav y jumper w ire betwe en neg ative terminal of lef t ba ttery andgr ou nd (fig. 39 ). If ligh ts burn, gr ound circu it is open or m astersw itch is defect ive. Check gro und c ircuit an d swit ch es with test lamp.C lea n and tig hten te rmi nals on gro und en d of cables.

(4) If lights do not burn, run ahe avy jum per wire from p ositive te rminal of left- or rig ht-han d ba ttery to low er termina l of shunt in appa ratu s box (fig. 39). If l ig htsbu rn, circu it is open on both lef t- and righ t-hand ba tteries. C heckwith te st la mp or jum per from te rminal to te rminal and correct co ndition on both left- and rig ht-h and circuit s.

(5) If lig hts still do n otburn, te st cables th at connect b a tteries, us ing a jump er. Replac e cable

if broke n or defec tive .(6 ) C heck each cellof each batte ry w ith hy drom eter and vo ltmete r. , I f bat tery is low,recha rge wit h outsi de source o r engi ne ge n erators, o r repl ace, as tactical situatio n permit s. If one or mo re cells are dead , repl ace u n itsc ont aining d efective cells.

BATTERIESDo N O TSTAY C H A R G ED. (1)Kee p one or bo th engin es runni ng at 1,500 rev olu tions

pe r minute w hile usin g el ectrical e quipm ent in accord an ce with th eload.

(2) C heck and se rvice charg ing c ir cuit (par. 4 6).

(3) Test each battery wit h hy drome ter and hig h discharg e test. R ep lace sub sta ndard batte ry uni ts. Chec k for bat teries connected w ith revers ed polar ity.

4 5. Ligh t in g Sys tem

a. No LIG HT S. (1) Reset l ighting sy stemcirc u it brea ker by p ressin g button on instrume n t panel (fig. 6).

Caution : If circui t bre aker w ill not sta y closed, do not ho ld inclosed p ositi on. C heck lighti ng circuit for sh ort o r ground.

(2 ) Us e test lam p or voltm et er to check powe r fe ed to l ig hting sw itch BATT ERY term ina l. I f there is noc urre nt to th is point, check b ack thr ough the fee d cir cu it (figs 40, 41 or 42) unt il the " short" or "open " is loc ated, an d repair or rep lace wiring or conduit as requ ired.

(3) If p ower feed -to-switch is satisfa ctory, use a jumper wire to con nec t BATT ERY term inal with o ther ter minals. If ligh ts b urn, replac e lig hting switch.

&. A LL L I G H T SDIM . (1) C heck b attery cond ition wit h h ydrome ter and volt meter. Re charg e or rep lace batte ries asrequir ed.

9 7

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(2) Check backthrough lightingswitch feed circuit with voltmeter to locate and correct high-resistancecondition.

(3 ) If circuit checks satisfactorily and all connectionsare tight, replace lighting switch.

ON E HEADLIGHT,TAILLIGHT,O RM A R K E RLIGHTDOESNor LIGHT.(1 ) Check lamp unit by replacing with one knownto be good.

(2 ) Clean any foreign matter from lampcontact.

(3 ) If replacement of lamp does not correct the condition, check backthrough circuit to lighting switch, usingtest lamp or jumper wire, and correct "open" or "shorted" conditionas required.

(4 ) If circuit checks back to lightingswitch, connecta Jumper between BATTERY terminal on switch andaffected terminal. If light burns, replace lighting switch.

T he foregoingprocedure also applies to the Instrument panel lights andto the dome lights, except that the circuits must be traced back.through theirrespective switchesand feeds (flgs. 40 and 47).

STOPLIGHTSDo NOT OPERATE. (1 ) Burned-out lamp. If onlyone stop light fails to operate, check for burned-out lamp by replace

ment. If only one light fails to operateand replacement of the lamp does not correct the condition, checkback through the circuit with Jumper or test lamp until "open" or"short" is discoveredand corrected.

(3 ) If neither service nor blackoutstop lights burn, check each of the stop light switches in turn by connecting the terminals with a jumper wire. Replace defective switch.

(4 ) If neither stop lightswitch proves defective, check circuit from main lighting switchthrough stop light switches and back, and correct any breaks or looseconnections.

(5 ) If circuit through stop lightswitches checks correctly, other lights will burn properly, but none ofthe stop lights will operate. Replace main lighting switch.

46. Charging System

G E N E R AT O R C H A R G E SLITTLEO R NOT A T A L L . (1 )Adjust drive belts to obtain %- to %-inch slack (fig.

50).Generator tests should be made on on e generator at a time.

(2 ) Test Battery with hydrometer. Iffully charged, regulator will prevent appreciably generator output.

100

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(3 ) Connectprecision ammeter in circuit. R eplace vehicleammeter if defective.

(4) Checkentire charging circuit (fig. 43 ) for loose or corroded connections using voltmeter, andcorrect any conditions causing high resistance. High resistance makes

regulator operate as if battery were fully charged.(5 ) Check regulator action by substitutinga regulator known to be satisfactory. If charging circuit is satisfactory, replace defective regulator.

(6) If replacement of regulator does notremedy condition, replace generator.

47. Electrical Instruments an d Equipment

T E M P E R AT U R EG A G ED O E SNor R E G I S T E R .(1 )Connect jumper wire from gage unit in instrument panel back toignition switch (fig. 45). If gage operates, replace feed wire.

(2 ) If gage does not operate when jumperwire is connected, gage unit is defective. Replace gage unit.

6. T E M P E R AT U R E G A G ER E A D SH I G H A T A LL T I M E S . (1 )D isconnect leadat engine unit. If gage drops to low side,

engine unit is defective. Replace engine unit.(2 ) If gage remains high with

wire disconnected,use test lamp to determine place where line betweenengine unit and gage unit (fig. 45) is grounded.

(3 ) If no ground is found in circuit, replacegage unit on instrument panel.

T E M P E R AT U R E G A G ER E A D SL ow A T A LL T I M E S . (1 )Connect test light to engine unit terminal and to

ground. If light does not burn, check back through circuit for looseor broken connection.

(2 ) If lamp lights, disconnectlead at engineunit and watch gage unit. If gage unit has high reading, engine unitis defective. R eplace engineunit.

(3) If gage unit does not show high readingunder the above circumstances, it is defective. Replace gageunit.

WARNINGS I G N A L SDo Nor LIGHTW H E NIGNITIONIs TURNEDON .(1 ) Burned-out lamp. If only one signal fails to light, the fault

is probably in the lamp on the instrument panel. Check by replacingwith new lamp (par. 93).

(2) If only one signal failsto light, and the lamp is not at fault, disconnectwire to affectedswitchon engine or transmission and ground it. If lamp lights, replaceswitch.

(3 ) If lamp fails to light, use test lamp to check

103

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7/28/2019 TM 9-744 155 MM M41


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32

7/28/2019 TM 9-744 155 MM M41


back through affected circuit (fig. 44 or 45 ), and correct conditioncausingopen circuit.

W A R N IN G S I GN A L S LIGHT. (1 ) Ordinaril y , lighted signals means high engine temperature , or

low oil pressure in engine or transmission. I f, however, a check of

gages and oil levels indicates nothing abnormal, check the electricalwar ning circuit as follows:(2 ) Disconnect lead a t

sw itch. If li gh t goesout, replaceswitch.(3 ) Check back thr o ugh affected circuit (fig .

44 or 45), using test lamp or voltmeter to locate and correct grounded condition.

/. SIRE N FAILST O O P E R A T E . (1 ) Push resetbu tt on on ins trument panel.

(2 ) Test switch with jumper wire. If sirenoperates, replace switch.

(3) C heck back th rough siren circuit (fig.42) with test lamp or voltmeter. Locate and correct "open" or "short"ondition.

(4) If circuit checks satisfactorily, siren is defective. Replace siren (par . 98).

SIRE N OPERATES WE A K LY. (1 ) Che ck w ith voltm e ter. Rechar ge or replac e affec ted b attery un its .

(2) Ch eck b ack through siren circ uit (fig. 42) with volt m eter. Lo cate and c orrect high resistancecondition.

(3 ) If circuit che cks satis fac torily, sire n is defecti ve. Rep lace the sire n .

FU EL P U MP S (O N E O R B OT H ) FA I L T o O PE R AT E . (1)P ush ci rcuit b rea ker reset button o n fuel switch br acket.

Open circuit b reaker would make both pumps inopera tive.

(2 ) T est fuel- pum p swi tch, u sin g jump e r wire.If pu mp op erates w ith jumpe r in place, re place swi tch .

(3 ) Chec k enti re pu mp -feed circu it (fig.46) f rom igniti o n switches to connec tio n at pu mp support. L o cateand co rrect ca use o f open circu it.

(4) If circuit chec ks to termin al onpum p su pp ort, remove su pport assemb ly from fu el tan k (par. Il l)

an d check lead to pump. R eplac e if de fective. On e ignit ion switchm ust be on w h en tes ting p ump circuit .

(5) If lead to pump chec ks satisfac to rily, pu mpis defect ive. Replac e the pu mp (par. Ill).

V E N TILATOR FAILS To O PERATE . (1 ) Pu shcirc uit bre aker reset bu tto n on left fr o nt of venti lato r assem bly.

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(2) Check feed circuit with test lamp at connector. If there is n o current, check back through circ uit (fig. 47)until open circuit is located and corrected.

(3) If feed circuit checks, ventil ator hasinternal short, broken switch, or other defect. Eeplace complete

v entilator assembly (par. 103 ).

48. Radio Interferen c e Suppres s ionPRELIMINARYI N ST R U C T I O N S .When checking rad io interference,

test the vehicle in a loca tion free from high-tension lines, ot her vehicles,machinery, and electrica l equipm ent which couldbe a source of interference. Stop engine and turn off all vehicle electrical equipment.Turn on radio and check noise level. Listen carefully to type of noisepresen t under these conditions. This registering of noise sounds isdone so that when vehicleequipment is checked, the presence of a newnoise or interfe rence can be immediately detected. Checking noiselevel is alsodone so that noisesalrea dy present will n ot be attributed tolack of vehicle suppression. If noise levelwith all vehicle equipmentshut off is too hig h, due to atmospheric conditions o r other outsidecauses, delay further checking if tact ical situation permits un til suchtime as mode ra te noise levelsprevail. Disconnect the rad io terminalbox capacitor (terminal end) (fig. 87). If rad io interference does n ot

increase,replace capacitor. I f interference increases,as it should, leaveterminal box capacitor disconnected for the remainder of the test s, oruntil any defective equipment has been located, replaced, and tested.Examine all shielded conduits and cables to make sure couplings aretight and co nduits and cables are clamped or bonded to hull at leastevery 2 feet.

6 . NOISE C A US E DB Y IGNITIONS Y S T E Mor VEHICLE ENGINES.Radi onoise causedby the enginesof the vehiclecan be determined by run ningfirst one engine and then the other engine. It is very unlikel y thatnoise will be present in both engines at the same time. However, ifsuch is the case, the remediesgiven below will apply for both engines.

(1) Examine condu it of ignition system and see that all coupling nuts and terminal connections aretight and tha t con duit is not broken or crushed (fig. 89). Ee pla ce anydamage d conduit or wires.

(2) Tighten allbond ing (holding) clips and tighten engine ground strap (fig. 88) .

If re medies given in this subparagraph do not correct the trouble,and the trouble is believed due to ignition faults, refer to higher authority.

NOISECAUSEDB Y GENERATOR. (1 )If radio op erator r eports the r adio interference as a c li cking sound, thetrouble is probably due to a faulty generator regulator. Tighten bolt sholdin g regulator unit to mounting stra p, tighten bonding s trap be-

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N.UO

RANGE (

/

HHEP, GREEN f

IGNITION SWITCHES

(EITHER S

WITCH

CLOSES FEED CIRCUIT)

- FRONT OF

VEHICLE

INSTRUMENT PANEL ^—I (

pump

circuit.

PUMP TERMINAL

N

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7

-

B{

C(

NO.14 RED, GREEN TRACER (

NO. 14 ORANGE (

FUEL PUMP

SUPPORT ASSEMBIY

PUMP TERMINAL

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-

1

RED (

-

14NAT.(

N

1

BLA

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TR.(9

N

.1

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CIRCUIT BREAKER

N

.14BL. RED TR. (

)

VENTILATOR

B

9N

.14N

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RED,BLACK TR. (

DRIVER'

DOME LIGHT

N

.14NAT.(

PLUG FOR WINDHIELDWIPER

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CIRCUIT BREAKERS

INSTRUMENT PANEL

STARTER

RELAYS

.$

7

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7/28/2019 TM 9-744 155 MM M41


tween regul ator mounting strap and apparatus box (fig. 90) . If noisecontinues,replace regulator (par. 82).

• remediesgiven in this subparagr aph do not correct the trouble, referto higher authority. •

(2) If radi o interference is caused bythe

generator system, tighten all bonding clips, coupling nuts, and gr oundst raps (fig. 88). Examine conduit and if it is crushed or cut, or inany way damaged, replace the cond uit and/or wires (par. 106) .Tighten con duit fittings in junction and apparatus boxes. I f noisecontinues, replace first one, and if necessary both, of the condenserswhich are found on the brush-h olding plate of the generator. Replacethem in the same positi on as the original ones were installed. If noisestill continues, refer to higher authority.

NOISYG UN MOUNTE L E VAT I N G E L E C T R I C A LSY STEM. If ra dio noiseis believed due to faults within the howitz er-m ount elevating electricalsystem, it can be det ermined by elevating weapon with vehicle enginesstopped . If ra dio interference is caused when weapon is elevated, thefault lies within th e following:

(1 ) Tighten all c ouplin g nutsand bonding clips. Replace all defective conduit an d/or w ir ing. Ifeit her strap or cable is damage d, refer to higher authority. Tig hten all conduit fittings in junction and control boxes and tig hten switchesand junction blocks in switch boxes. If noise con tinues and troubleis not remedied, refer to step (2 ) below.

(2 ) If cause of radio interference is not trace able to(1 ) above, it is probably due to a faulty motor. In either case, ref erto higher authority.

NOISEC A U S E DB YM I S C E L L A N E O U SS Y S T E M S .Noise may be causedby loose or damaged co nduits or wires of the lighting systems, variousinstruments in cluding their respectivesending un its such as fue l tank

gages, engine tem perature gage and sign als, oil-pr essure gage andsignals, and speedometer and tachometer. Variou s instru ments on theinstrument panel and in control boxes may become loose. Batteryterm inals and gro und cable of the batteries may work loose or becomecorroded or otherwise damaged. The lights of the vehicle and theirswitches, as well as the cap acito rs in wind shield wipers, are alsosourcesof radio noise.

/. L OC AT I O NA N D REMEDY O F M I S C E L L A NE O U S R A D I ONOISE. Thesame gen er al rule for maintenance of variou s systems, instruments,and devices mu st be followed as given previously concerning correction of r adio interfe re nce. A process of elimination can be applied tolo cation of trouble within any system.

RA D I OINTERFERENCE N O TT R A C E A BL E T O AN Y E L E C T R I C A LSY S T E M . If radio interferen ce persists in spite of remedies set forth into and incl uding / above,th e trouble is probably due to defect ive radio

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apparatus o r to faults within the structu re of the vehicle. Re fer to higher authority.

49. Cool ing Sy stemLoss O F C O O L A N T .Inspe ct all hose connections for leaks and

tig h ten where leaks are evident. If tighte ning does n ot stop leakage,re place hoses. Insp ect therm ostat h ousing and rad ia tor outlet elbowfor leakage at gasket and replac e gasket if require d. Look for lea k ageat radiator cap gasket when engines are at max imum oper ating tempe ra ture and replac e complete cap if le akage occurs u nde r pressure.Look for leaks at transmi ssion-to- engine w ater pipes. T igh ten connectionso r rep lac e pipes and fitt ings as required. Inspect water pum pfor leaky packings, and notify h ighe r au thority if thi s conditi on isfound. Look carefully for leaks at radia to r core and tanks, and repair or re place radiator as requi red. Check for leakage at cylind er heads and blocks. Tighten head screws to 65 to 70 foot-pou nds orreplace g asket as required to cor rect leakage. If head or block is cracked, replace entire engine.

& . E N GIN E O VE R H E AT S .See paragraph 42e.c. No WAT E RC I R CU LAT I O N .Inspect the cooling system water level

an d refill to brin g coolant u p to proper level. Afte r refilling, checkcomplete system to determi ne cause for loss of coolant. Insp ect the

drive belts and a d just to obta in %- to % -inch slack measured midwaybetween water p ump a nd genera tor pu lley (fig. 50). Ee place badl ywo rn or damag ed belts. Caution : Belts must be replace d in match ed sets of three except in an emergency. I f the latter is the case, the beltsshould be removed and repl aced with a set of match ed belts as soon asthe conditions pe rmit . If, after checking the above conditions, there isstill no circula tion, remove the thermo st ate housing an d check thetherm os tat. If th erm ostat is correct, clean cooling system thor oughly(par. 115) to restore circula tion. If coolan t does not ci rculat e aftersystem has been cleaned, remove water pump and inspect for she aredimpeller. If im peller is sheared, n otify h igher aut hority.

50. Fuel Sys t emLA CK O F F U E L A T C A R B U R E T O R .Check positi on of fuel p ump

switches an d turn to "ON" position. M ake cert ain that fuel tank isn ot empty and replenish fue l supply if necessary. Check cond ition ofcar bureto r st rainer screen a t carburet or an d also check auxilia ry fuelfilte r at carburet or inlet fitting. Clean if necessary. Inspect fuel linesfor clogged or leaky condition and clean or replace as necessary. Remove fuel p ump support an d clean strainer screen, and screenon pump and reinstall (par. 111). Check fue l pump to find outif p um p moto r operate s by listen ing for pump motor with fuelswitch turned on and vehicle engine not running. If inoperati ve,

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replace pump or notify higher authority. Inspect fuel valve, andcheck valve a t tank and free up or replace if inope rative. Checkfuel valve cable to make certain cable not broken, disconnected, orloose and out of adjustm ent. Reconnect, readjust, or replace asnecessary.

C A R B U R E T O RNor OPERATINGP R O PE R LY . Check choke thermostathousing adju stment and reset to indicator mark, if necessary (fig. 93).Check to be sure choke is free from all sticki ng or binding . If chokecannot be freed by moving lever on end of shaft (fig. 94), notify high erauthority. Check ca rburetor adjustments (par. 110) to make surefault is not in the adjustments . If above measures do not correct thedifficulties,re place carbure tor or no tify higher authority.

51. Tra n s m i s s i o n

LUBRICANTLEAKS. Check tran smission for oil leaks at th e drainplug, oil pa n, and side cover. Tighten drain plug or cover attachingscrews to stop leak. If leak will not stop, replace ga skets o r drainplug. I f fluid coupling is found to be le aking, do not attempt torepair. N otify hi gher authority.

TRANSMISSION FAILST O T R A N SM IT PO WER. Check transmission oil level and fill to level mark on gage (par. 33 ). If oil level was low,check tr ansmission thoroughly for oil leaks. If transm ission still doesnot function, adjust m anual control linkage (par. 121) . As a finalstep, check the front band adju stmen t (par. 122) and rea djust asrequired.

Rear ba nd has automatic adjustment and does not require at ten tion.

TRANSMISSIONS H I F TS P E E D S A B N ORM A L . If all shifts occur atexcessivelyhigh engine speeds, check vacuum line between transmission and intake m anifold for leaks at fit tings or cracks in line. Repair or replace as necessary. If engine speeds up in first and thirdwhile being driven forwa rd , the fr ont band is out of adjustm ent.

Rea djust front band (par. 122). If engine speeds up in first andsecond,rear band is out of adjustme nt. Rear band adjustment is automatic; if band is slipping, no tify higher authority. When all sh iftsabove second occur at excessive engine speeds, the manual controllinka ge is improperly adjuste d. Readjust manual con tr ol link age(par. 121).

VEHICLEC R E E P S .C heck engines to make sur e idling speed isdown to 450 revolut ion s per minute and that throttle link age does notbind. Eliminate b ind in throt tle linkage and replace missing or weakthrottle return springs .

5 2. Propel le r Sh aftsVIBRATIONA T UNIVERSALJOINTS. Replace all propeller shaft

joints having worn needle bearings. Check shafts fo r run-out and replace all affected shafts.

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& . H E AV Y T HU M P S RO U G H TER RAIN. Check tr ansfer unit univers al join t sli p yokes to m ake sure yokes are free on sha ft splines. Replace frozen slip joints,

O IL L E A K AG E AT UNIVERSA LJOINT S. Check oil seals at universa ljoints an d re place affected prope ller shaf t joints.

5 3. Transfer Un itT R A NSFER U N I TD O E SNo r R E S P O N DT O CO N T R O L LE V E R . Check

sh ifter sh aft extensions to deter min e if extensions are loose on sh if tershafts. If loose, tighte n and read just co ntrol rods (par. 130). If extensions are no t loose, check transfe r u n it control ro ds for adju stm enta nd adjust if necessary (par. 130). If trans fer unit will not sh if tp roperl y aft er checkin g above op erations, check the yokes on the sh iftershafts. If yokes are loose on sh ifter shaft s , replace transfe r uni t or

notify h igher au th ority.6. TRANSFER U N IT O V ER H E ATS . Check trans fe r unit oil level an d, if

necessary, add oil to bring level up to fu ll mark on gage. If oil is low,check uni t to de termin e cause for loss of oil. If oil level is to o hig h ,dr ain or siph on until oil is at FUL L mark on gage. Too high an oil level will cause excessive foami ng which will cause overhea tin g. Iftra nsfe r uni t continues to overheat, check the oil pu mp o p eration inthe foll owing m anner: Open slidin g door over transfer u nit a ndremove one of the y -inch pipe plugs from to p of case. Star t engines,place transfe r unit shift lever in N EUT RAL p osition, an d tran smission lev er in D RIV E. If oil pump is ope ra ting pro p erly, oil will flow ou t of the plu g opening. If no oil flows fr om plug open in g, noti fyhi gh er auth ority .

G E AR S C LASH W H E NS H I F T I N G .I f gears clash in cold weat her,it may be tha t the tr ansfer un it lubricants have not been warmed upsufficiently. St art engines and place trans fe r unit sh ift lever inNEUT RA L and transm issio n selector lever in DR IV E. Allow en

gines to run until the transfe r un it warms up. Check for pr operseasonal gr ade of lubri can t. If ge ars clash due to impro p er use o f thene u tral peda l, review th e drivin g in structions (par . 15). If gears cont in ue to clash, check th e transfer unit co ntro l linkage an d adjustas necessary (pa r. 130). If gear s clash afte r adjustm ents have beenmade, clash is likely to be due to the clutch sy nchronize rs not oper at in g properly . N otify h igher a utho rity.

54 . Co n t ro l led DifferentialV E H IC LE HAK D TO S T EE R O R S T O P. If vehicle is hard to steer o r

stop, check steer in g brake ad ju stment and adjust as necessary (par.134&). If brake ba nd s are h ig hly glazed or worn, re place band s(pan 135).

6. B R A K E SR E Q UIR E FRE Q U E N T A DJU S T M E N T.I f vehicle bra kes require ad justments frequently, driver should observe driving in struc-

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tion s (par. 15) to insure prope r handlin g of vehicle. If br akes continue to requir e adjustments, check brake rims for roug hened condition. I f fou nd to be rou gh or damaged, n otify higher aut hority.

55. Track s an d Suspens ion

SUSPENSION WHEE L TIKE WEAR. If suspension wheel tires showexcessive wear, check track blocks fo r bent guide or oth er da magewhich would have tende ncy to cut or wear tires. Repair or replacedamaged blocks or tracks as necessary (par. 14 4).

6 . TH RO WN T R A CK S . If track was thr own, check complete suspension to determine cause. Impro per track tension, damaged compensating wheels, foreign matter between tra ck and wheels, or a brokenfront torsion bar are the most likely causes for the track to be thrown.Adju st trac k tension (par. 143) ,replace damaged compensatin g wheels(p ar. 145) , clean out for eign matte r, or re place br oken torsion b ar(par. 149) .

I N O P E R AT I V ETRAC K S U P P O R T I N GRO L L E R .Check roller to makecertain no foreign matter is caught between tr ack roller and track,or between track roller and support. I f roller is free of foreign matter, check bearing adjustm ent. If bearing has seized, replace rollerassembly (par . 151).

I N O P E R AT I V EC O M P E N S AT I N GWHEE L. Check compensating wheel

to make cer tain no foreign ma tter is caught between wheel and track,or compens ating wheel sup port. If wheel is free of foreign matter,check wheelbearin g adjustment. If bearing has seized, replace bearings (pa r. 145).

Sect ion XVI. EN GIN E DESCRIPTIONA ND MAINTEN A N C EIN VEHICLE

56. Engine Descr ip t ion and Data

DESCRIPTION.(1) This vehicle is powered with tw o 90° , V-type,8-cylinder, 4-cycle, liquid-cooled engines (fig. 48), m ounted side-by-side in th e engine compartme nt in the center of the hull. The enginecylin der blocks and crankcase, made in one casting of grey iron, support the crankshaft and cam shaft, and enclosethe reciprocati ng parts.C ylinder heads are of cast iron also. The cylind ers are arrange din tw o ban ks of four each, located 9 0° apar t. O pposite conne ctingrod assemblie s operate side-by-side from the same cranksha ftjournal.

(2 ) The distr ibutor, ignitio n coil and wiring, carburetor, in ta keand e xhaust manifolds, and cylinder he ads are accessiblethrough theengine compa rtment hinged air outlet grille. The starter and the engin e oil pan are accessible th rough an in spection opening with removable cover in the hu ll floor. The belts, water pump , generator

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and oil filters a re accessible after removing access plates at rear ofengine compartment .

(3) The generator end of these en gin es is designated the front end,even though it faces the rear of the vehic le, and the flywheel end isdesignated the rea r end. The right and left sid es of each engine (andtransmi ssion) are determined by standi ng at the transmission andlooking toward the gen erator end. Right- and left-hand engines inthe veh icle, however, are designated acc ord ing to their relation to am an sitting in the driv er's seat. T he engine on the right of the hu llis th e right-hand engine . E ngine supports, cushions, and a ttachingbrackets an d bolts ar e considered with refe rence to their position inthe h ull ra ther than their relation to the engines. Thus, the supportunder the tra nsmission is desig nated as the engi ne front supp ort,alth ough it attaches to the rear of th e eng ine, and the two supports

at the generator end are the en gine rear su pports.

5. D ATA .Bore and stroke— — — _ — — — — — — _ — — — — .3y 2 x in.Compres sion rat io____________—— 7.06 to 1.Cy linder numberi ng_________ ____. Refer to fig. 74.Engine make__ ____ ___—____—. Cadilla c.E ngi ne supports, num ber of _____ _____. 4.

IGNITION COIL

BY-PASS HOSE

F OR COO LANT

LIFTING EY E

C R ANKCASE VENTILATING

AIR CLEANER

iXHAUST MANIFO LD

CROSS-OVER

SOLENOID

CRANKING M OTOR

ENERATOR

ENGINE S U P P O RTREAR CUSHIONS

NGI NE SERIAL NUMBER RA PD 331806

48.

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DA T A(Contin ued ).Firing o rde r________ __ _—_—— - 1 ,8,7,3,6,5,4,2

(f ig. 74).Hor sepower, net i ns talled-____ __ ___. 110 @ 3,400 rpm.Pist o n displac ement (each)_— ____— _— 346 cu. in .V alve a r rangemen t————— — — — — — — — —— . L-head.Weigh t of engine and transmission assem- 1,166 Ib.

bly.

57. Engine Tune-UpThe op erations requ ired for a complete engine tune -up are listedbelow.

Clean and ad just or replace sp ark plug s (par. 75).Clean and adju st, or replace contact poin ts (par. 70).

Check ignitio n ti ming (par. 7 3).Clean ca rb uretor auxiliary filters (par. 110).Service carb u retor air cleaners (par. 109).

/. Adju st carbu retors (par. 110).

5 8. Oper atio n s Pe r fo r m ed W ith Engines in VehicleThe foll owing operations can be perfo rmed with out removing the engines fro m th e vehicle (fig. 49) :

A djust or re place belts (par. 59).A dju st car buretor (par. 110).Replace c arbu retor ( par. 110).Service c arburetor a uxilia ry filter (par. 11 0).Servi ce cooling system (par. 115).

/. Jleplac e cylinder head gasket s (par. 60) .Replace d istributo r (par. 70) .Adjus t or rep lace distribu tor contact points (pa r. 70) .Replace generator (p ar. 81).Rep lace hose connections (pa r. 116) .Replace ignition coil (par . 71).Replace ign ition condenser (par. 7 2).

A dju st ign ition ti m ing (par. 73).Replace igniti on wiring (pa r. 74) .Rep lace manifo ld gask ets (par. 65).Replace m anifo lds (par . 65).Service or replace oil filter (par. 62) .

Replace oil filter connections (par. 62) .Replace oil pan (pa r. 63).Replace oil pum p st rainer (par. 64).Replace si gnal sending units (p ar. 97) .Ad just or replace spark plu gs (par. 75) ;Replace sta rter (par. 77).Replace water pum p (par. 109).

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Cautio n: Do not use a screwd river or oth e r sharp inst ru ment to p rybelts off pulleys, as thi s may cause nicks or bu rs on pu lleys and shorte nlife of belts. Remove and in stall belts by han d.

(3 ) Install three new belts over pulleys. Belts ar etie d in ma tched sets of three and must not be separ ated u ntil re ady

for actua l installatio n.C aution: Never install one new be lt with two old belts except in an

emergency; belts sh ould always be replace d in sets of thr ee. Connectgenerato r wires (fig.66).

(4) S ee (4 ) above.(5) Ref er to (5)

above.(6) Close engine com partm ent doors

and turn la teh handles to locked position.

60. Cylinder H ead Gaske ts(1) Turn bo th latch es

at side of doors to unlocked position and raise doors. A fold ing propis hinge d to front edge o f door and may be used to hold door in open position.

(2) R emove drain cove r unde r tran smiss ion by

remo ving four screws. R emove p lug at bottom of transm issio nmarked "WATER " (fig . 27). Remove radiator cap to vent systemand th ereby speed draining.

(3 ) Disconnect spark plu g cond uits fro msp ark plugs. Usin g a deep socket wrench, remove spark plugs and spark plug gaskets (par. 75).

(4)R emove tw o screws holdin g engine uni t signal se nd ing conduit

to left cylind er head. Disconnect wires fro m units by p ulling strai ghtout of uni ts.

(5)Disconnect feed wire fro m resis tor te rm inal a t bottom of

coil by removing nu t and washer.Make sure m aster batt ery swi tch is in the OFF posit ion. Remove two

cyl inder head sc rews which hold coil moun ting bracket to cylinder he ad. Positio n coil and su pport bra cket out of way to pr ovide acce ss to head scr ews.

Cau tion: D o not lin k coil or spar k plug cond u its; disconnec t if nec

essary (p ar. 75).(6) Remove two special screwsho ld ing water outlet elbow to cylinde r head . Le ave o utlet elbow attache dto hose. On right cyli nder head, le ave by-pass hose attach ed to e lbow.

(7) R emove all re ma ining cylind er hea dscrews (except th e lower row on outsid e ba nk of cy lind ers) and remove

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cylinder he ad gaske t. Lower ro w of screws on outside bank of cy linders hav e to be unscrewe d an d rem oved with the cy linder head.

C auti on: Support cylin d er head while rem oving last screws to prevent head fr om s liding down and damaging valves.

In stall cylin d er head gasket. Coat new cylinder head ga sk et with gas ket sealer on both sides and position o ncylind er block. B e sure surf aces of block and head are clea n an d freeof carbon or other p articles.

(2 ) Positi on cylinder head o ver gasket,being careful no t to damage gaske t or valves. Du e to the slight clearan ce betw ee n the hull side wa ll and cylin der head, it is necess ary toplac e the lower row o f cylinder head scre w s a nd the en gine lifting ringon the ou tside c ylinder he ad befor e h ead is lowered into final position.

Be sure en gine lifting ring is in pro per loca tio n on cylinder hea d (fig.51 ). Insta ll (but do not tigh ten) all screws w it h the exception o f thetwo lon ger screws th at hold the water o utlet elbow and th e two thatattach the ignitio n coil moun ting b racket to the cylin der head.

Cauti on: The two screws that h old the outlet elbow to cylinder head hav e spec ial heads an d are longer th an the other screws and must notbe used in any othe r position o r else cylinder bloc k may be damag ed.

(3) Coat a new water outlet elbow

gasket with ga sket sealer an d po sition on cylinder h ead. Place out letelbow over g as ket and install the two cylinder hea d screws w ith th esp ecial hea ds (long screws ).

(4) Posi tion coil andmounti n g bracket over th e two center hole s on cylinder hea d (righ tc ylinder he ad only ) and install two attaching screws (fig. 69). Donot tighte n a ttach ing screws a t thi s tim e. Co n nect feed wire to re-si ster term inal at botto m o f coil and connect c onduits to to p o f coilif n ecessary (p ar. 74).

(5)Posi tion en gine unit signal se nd ing conduit on cylinder-head

and install two attac hing screws and w ash ers. T ighten all cylinderhead scr ews to 70 to 75 foo t-poun ds torque.

Caution. Cy linder head screw s must be tightene d evenly and in th e o rder shown (fig. 5 1).

(6) Ins ta ll spark p lug ga sket on spark plug s.Using a dee p so cket wrench, insta ll spark j lug and g askets, tig htening

plugs to a torque tigh tness o f 7 to 10 fo ot-poun ds. Connec t spar k plugcondu its (par. 74).

(7) In st all drai n plug in bottom of tran s mis sion. C oat edges of d rai n cover an d ga sk et und er tr ansm issionwit h sealer and in sta ll gask et, cover, a nd scre ws. Fill co o ling systemto p roper level. Inst all radiato r cap. Kun engine unti l it reaches

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L O N G S C R E W S E N G I N ELIFTINGR I N G

WRENCH(4 1-W-3630) 70-75 FOOT P O U N D S - '

normal temperature and again check torque tightness of cylinder headscrews (70 to 75 foot-pounds torque, fig. 51) .

(8 ) Close door and turn handles tolocked position.

£ R A N K C A S E A I RC L E A N E RC O V E R MOUNTING B R A C K E T ELEMENT

'ifcS M H H BBBk.'C"-"l

O IL R E S E RV O I R - '

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61 . Cran kc a s e A ir CleanerDESCRIPTIO N. Eac h engin e is equipp ed wi th a crank case oil bath

air clea ner, mount ed on the intake ma ni fold. W he n engine is o pera ting, ai r is drawn thr o ugh the a ir cleaner, circula ted throug h th ecrankc ase, and th en d rawn o ut of cran k case by ma nifold vacu um. It

then passes thr ough the in take ma nif old an d out throu gh th e exhau stsystem .

SERVICING. To servic e and c lean air cl eaner ele ment, u nscrewbowl from cover (fig. 52) and wa sh bowl and elemen t in dry clea ni ngsolvent. Dry p arts th oroughl y w ith air hose, fill bowl to "FU LL"

m ark with clean oil, place elem ent ove r stud, and rea ttach bowl tocover.

C au tion: B e sure g aske t is in good con dition a nd in prope r posit ion.

62. Oil Fil terD E S C RIPTION. Ea ch engine is e quipped w ith a mi litary , senio r-

size oil f il ter mount ed in a bra cket attach ed to the f ro nt en d o f theeng in e. Oil enters the fi lt er thr ough a pipe con nected to the ma in oil header at the front of the en g ine block. Aft er the oil passes th rou ghth e fi lter, it is retu rned to the engi ne through another pi p e connec te dto the en gi ne front co ver (fig. 54) .

6. SERVICING. (1) O pen engin e compartm ent h inged air outlet doors.

E L E M E N T

OIL F I LT E R BODY

D R A I N PLUG

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(2 ) Ke fer to p aragraph 5 9 < ? (3).

(3) Kemove hex screw from top of oil fil tercover and rem ov e cover and g asket. Discard the gasket. Rem ove oilfilt er elem ent by l ifting out of filte r (fig. 53). If fi lter element is ti g ht,

be care ful not to nick the gaske t surface on the filt er body in pr yingthe ele ment o ut.

Cau tion: Be su re n o oil is a llowed to splash on b elt s in thiso peration.

(4) Eemove drain plu g fr om bo ttom of filter andallow ol d oil to drain. Wash insi de of f ilter with cle ani ng solvent,wipe d ry, a nd reinstall drain plug. Clean an y spilled oil from filterbody and hull floor.

(5) Inst all ne w e lement in filter bo dy. P lacenew gasket in cover and ins tall cover and tig hten screw to 18 to 22foot- pound s to rque.

Be sure cover is sea ted squarely on body befo re tighten ing screw.

(6 ) R un engi ne for sev era l minut es to allowfilter to fill with oil. Inspe ct for oil leak s. Check engine o il leveland add oil if necessar y.

(7 ) Refer to parag raph 59c (5).

(8 ) Close engine comp artment do o rsand turn handles to locked p osition.

R E M O VAL . (1 ) Open engin e compartment h inged doors.

(2 ) Ref e r to paragraph 59c (3) .

(3 ) Pla ce rags or conta ine r under oil fi lterto prev ent oil runn ing over hu ll floor. Discon nect inlet pipe a t topo f filter by u nscre wing flared tube nut from elbow. Di sconnect outl etpipe at bo ttom of filter by unscre wing flare d tube nu t from elbow.

Caution: Be sure no oil is allow ed to spl ash on b elts in th is o perat ion.

(4) Rem ove tw o n uts an d bolts from cla m p strapsand lift out filter assemb ly (fig. 54).

(5 ) Dis connect inlet pipe from fit

tingconn ected

to main oi l hea der a t f ront of cyl inder block. Disconnect outlet p ipe from fitting on engine front cover.(6) Rem ove three n uts a nd

wa shers ho lding mo untin g bracket to fron t of cylind er block. Removethe b racket.

(7) Position m ounti ng bracket o ver studson front of cylinde r block and insta ll three nuts and lock washe rs.

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(8) Connect o u tlet p ipe to fitti n g on engine fr ont cover and in let p ipe to fitting a t m ain oil hea de ron fro nt of c yl inder block.

Tighten pipes finger-tight.

(9 ) Posi tio n oil filte r assembly in

m oun tin g b racket and ins tall tw o clamp bolts, nuts, an d lock washers .Connect out let pipe to elbow on bott om of fil ter and in let pip e to elbowon side o f filter. Tig h ten all connections.

'MO UNT ING

CLAMPS-D RAIN

P LUGOUTLET LINE -IN LE T LINE

(10) Ru n engine for several m inutes to allow fi lter to fill w ith oil. In spec t for oil leaks. Check engin e oil level an dadd oil if necessary .

(11) Re fer to para gr ap h 59 c(5) .

(12) Close engine compa rt ment doorand turn latch h andles to locked position.

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63. O il Pan an d Gasketsa. R E M O VA L .(1 ) R emove 18 screws from

hull floor plate under engine compartment.

Cau tion: S up port rear en d of plate whi le rem ovi ng last scr ews toprev ent plate from droppi ng and ca using pers onal injury.

Front end of plate is he ld up by hooks on cover. Slide plate tow ardrear of veh icl e and lower to gr oun d.

(2) Remove engin e oil pan dra in p lug and allowoil to drain. R einstall drain pl ug with gasket a nd tighten to 35 to 40foot-pounds torque.

(3) Remove 25 oil pan screws. Lower rear end ofoil pan and s lide p an out through hull floor opening.

(4) Wash oi l pa n thoroughly with dry cleanin gsolv ent. R emove a ll porti ons of oil p an g askets from pan an d bottomo f cylinder block, and discar d.

& .IN S TA L L AT I O N. (1 ) Coat gas ket surface of c ylinder block lightly with jo in t and thread com poun d (cemen t, type-II) to h old gaske ts in position . Pl ace gaskets on oil pa n or on cylind erblock.

(2) Slide front end o f oil pan carefu lly throughhu ll floor opening. P osition front end of pan on cylin der block and

rais e rear end of pan into positio n. W hile holding oil pa n up againstb lo ck with one han d, ins tall two or three screws to p revent pan drop ping down. In stall balance o f screws and tight en to 7 to 10 fo otpounds, using a torq ue wrench.

OIL STRAINER FLOATASSEMBLY

Fig ure 55. R emov ing oil pump strainer

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(3) Coat edges of floor plate with jointand thread compound (cement, type II) and place gasket on plate.Raise front edge of plate until hooks on plate rest on hull floor. Eaiserear end of plate and line up screw holes with tw o drift punches. Install floor plate retaining screws.

(4) Eefer to lubrication order (par. 32) .

64. Oil Pump StrainersR E M O VA L .(1 ) Refer to paragraph 63a.

(2 ) Removecotter pin holding oil pumpstrainer and float assemblyin oil pump body (fig. 55) . Slide float andstrainer assembly out of oil pump.

(3 ) Inspect float assemblyto see that oil has not

entered the float chamber. Shake assembly to detect presence of oilin float. If oil is found in float, unit should be replaced. If no oil isfound in float, wash strainer thoroughly in dry cleaning solvent andblow dirt from strainer mesh.

INSTALLATION.(1 ) Slide oil pumpand strainer float assembly into oil pump body. Install cotter pin.

Raise and lower strainer assembly several times to make sure it is freeand that it will drop down of I ts ow n weight.

(2 ) Refer to paragraph 636.

65. Intake and Exhaust Mani fo ldsR E M O VA L .(1 ) Refer to para

graph 10.(2 ) Turn latches on engine compart

ment door to unlockedposition and open door.(3 ) Refer to paragraph llOc.(4 ) Refer to paragraph 113J .(5 ) Remove four screws holding ex

haust connection to left and right exhaust manifold; lift up connections and discard gaskets.

(6) Disconnect conduits at sparkplugs. Remove four nuts holding ignition wire conduit supportbrackets to manifolds. Lay brackets and wires to one side.

(7) Remove tw o nuts and washersholding engine crankcase air cleaner to intake manifold. Loosen

lower hose clamp and remove air cleaner assembly.(8) Removeclevis pin from

lever on center of relay cross shaft. Disconnectthrottle rods at crossshaft levers. Removetw o nuts from relay cross shaft support (fig.56) and slide cross shaft out of other support.

Do not lose springs or washers from ends of cross shaft.

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(9) Remove re main ing nuts an d clam psh oldi ng e xhaust ma nif olds to cylin der block (fig. 57). R emoveman ifolds.

(10) Bend back loc k plates and removefou r screws ho lding fan sh aft uni versal joint to yoke at re ar of intake

manifo ld. Bend back lo ck p lates and remove fou r screws holding fansh aft un iversal joint to yoke at fro nt of intake manifold . R emovefour intake m anifold screws (fig. 57) and lift out manif old (f ig. 58). Discar d gaske ts.

INSTALLATIO N . (1 ) Clean gasket surfac es oncrankcase and manifo lds. Place two n ew in take and exhaus t manifoldga sk ets on cylinder block.

(2) L ower intake m an ifold into p ositio non cy linder block. In stall four sc rew s holdi ng intak e manifold tocy li nder block. U si ng a torque wre nch, tighten scr ews to 25 to 30foot-pounds. Connect fan sh aft univers al joi nt at rear of ma n ifoldand in stall four sc r ews and lock plates. Bend lock plat es over headof screws. Conn ect fan shaft uni versal joint at fr ont o f manifol d an dinstall fo ur screw s and lock plate s. Ben d lock plate ove r head ofscrews.

(3) Place both e xh aust manifolds ong askets and ins tall intake and ex haust manifold clamps and cla mpnuts. Us ing torq ue wrenc h, tight en nut s to 25 to 30 foot-po u nds.

Be sure to install spar k plug wire condu it support brackets orer thecen ter s tuds on both s ides, and to placs carburetor retracti ng spring clip over left front stud and transmission filler pipe clip over rig ht rear stud.

(4) Install two new exhaus t manifoldconne ct ion gaskets on e xhaust m anifold s and install con nection a ndfour mountin g screws. Apply an tiseize compoun d (white lead bas e) to threads of these screws. Us ing torque wrenc h, tighten sc rew s to25 to 30 foot-p oun ds. After running engine a short tim e, reche ck allman ifo ld screws for pro per torq ue ti ghtn ess.

(5) Slide air cleaner hose over aircle aner front pipe o n valve co mpartm ent cover. Po s ition air cleanerm ounting bracket over mountin g st uds and install n uts and wash ers .T ighten lo wer hose clam p on air cleaner pipe.

(6) Refer to p aragraph HOrf.(7) Sl ide end of upper rear

relay cro ss sh aft through mou nting bracket on intake manifold .Ma ke sure sp ri ng and washe r are on end of cross sha ft before installing

in brack et.

Pla ce mounting bra cket on opposite end o f cross shaf t, mak ing sur espring a n d washer are i n position on en d of cross shaf t. Installm ounting nuts and lock washers (fig. 56). Connec t rod from u ppe r

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M O U N T IN G S TUDS S UPP ORT -S P R ING

THROTTLE RO D DIS CO NNE C TE D 1 '~ THROTTLE CR O S S S HAF T R A P D 33 17 99

F ig u re 56. D is c on n e c tin g up pe r re la y c ro s s s h a ft .

re a r re la y to lo w er re ar re lay b y in sta lli ng cl ev is p in , f la t w as he r, an d

co tte r p in a t u p p e r rea r rel ay . C o nn ec t th ro ttl e ro d s to le ve rs on c ro ss sh aft . A dj us t t hr o tt le lin ka ge as e xp la ine d in p a ra g ra p h

(8 ) R efe r to p ar ag ra p h 113.(9 ) Close eng in e co m p a rtm en t

d o o r an d tu rn la tc h h a n d le s to lo ck ed po si tio n .

6 6 . E n g in e M o u n t in g s — R e p la c e m e n t

R EM OVE EN GINE S. R e fe r to pa ra gr ap h 67.5. REMOVE ENGINE CU SH ION SUPPO RT S. R em ove scre w s a nd w as he rs

h o ld in g eng in e cu shi o n m o un tin gs to eng in e s u p p o rt b rac k e ts . R e

m ov e ru b b er cu sh ion s.IN ST ALL ENGINE C USHION SUPPOR TS. P la ce en gi n e cu sh ion m ou nt

in gs o ve r e ng in e su pp or t b ra ck et s an d in s ta ll scr ew s an d w ash e rs. U sin g a to rqu e w ren ch , t ig h te n screw s to 45 to 50 fo o t-po un ds .

INSTALL ENGINES. R ef er to p ar ag ra p h 68.

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Section XVII. ENGINE REMOVALA ND INSTALLATION

67. Engine Removal

AUTHORITY. Replacement of this major assembly with a newor rebuilt unit is normally a field maintenance operation, but may beperformed in an emergency by battery maintenance personnel, provided authority for performing this replacement is obtained from theappropriate comm ander. T ools neededfor the operation which arenot carried in organizational maintenance units may be obtained froma higher maintenance unit.

EQUIPMENT.The only special equipment necessary for removalof the engine is a sling ( 4 1 - S - 3 8 3 1 - 3 0 0 )and a chain hoist.

P R O C E D U R E .T he procedure that follows applies without change either to a right

or left engine.

-MANIFOLD C L A M P S;rv jjr jr

E X H A U S TMANIFOLDS

EXHAUST MANIFOLD C R O S S O V E RINTAKEMANIFOLD S C R E W S

I N TA K EM A N I F O L D " ?

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(1 ) T he master batter y switch islocated on th e fro nt of th e bu lkhead near the left side wall (fig. 5).Pull out on switch knob and tu rn about one-qua rt er turn to lock inopen position.

(2) Eleva te howitze r to abo ut 60°. Tra versehowitzer to left or ri ght to provide additiona l clearance when removing engine.

(3) Tur n la tch handles onengine co mpartment doors to unlock po sition. Eemove tw o bolts a ttaching angle plate a t rear of doors (in cen ter) an d remove plate(fig. 59). Slide doors toward rear and remove from enginecompartment.

(4) Remove stowage from shieldstowage box (left o r rig ht), and lif t box off side of vehicle.

(5 ) Unfa sten strap holdin g watercan to holde r and remove can. Eemovefour screws, lock washers, andnuts attac hin g water can hold er to stowage box suppo rt and removeho lder.

(6 ) Kemove screw a ttaching ex

haust pipe extension to muffler outlet elbow (fig. 60 ). Remove exha ust pipe extension rear suppor t bolt, washer, and nut, and p ull extension out of muffler outlet elbow.

(7 ) Remove four bol ts attachin g cover to hull a t rear of engine compartment (fig. 59) and liftoff cover. Remove fou r bol ts attachin g engine comp artment rearplat e to bulkh ead at r ear of engine com partmen t (fig. 59) and removeplate .

(8) Remove four screws from drain p late un dertransmis sion and remove plate. Drain coolant from engine by removing drain p lug at bottom o f transmi ssion m arked "WATE R"(fig. 2 7). Remove radi ator cap to vent system and speed drainin g.

(9) Remove tw o screws, nuts,and w ashers holding muffler moun ting flange to exhau st ma nifoldflange (fig. 61). Remove muffler and exhaust outlet pipe assembly.Discard gasket.

(10) Disconnect choke thermostat air line at intake elbow and at manifo ld by unscrewing connections from fitting . Disconnect dis tributor ven tilatin g line at airintake elbow by unscre w ing connection. Loosen air clean er and elbow assembly clam ps (fig. 62) . L ift assembly off top of carbureto r andslid e end off air clea ner hose at engine compartm ent side wall.

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HAIRPIN L O C K — i F U L C R U ML E V E R -7 TRANSMISSION

-CONNECTINGL I N K CLEVIS PIN J " " T R A N S F E RUNIT

A R M AT U R EL E A D (NO. 202-2)

RAPD 331266

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(16) Remove screws from h ull floorcover.

Caut ion: Support rear end of cover while removing last screws top revent cover fr om dropping down and causing injury.

Front of cover is held up by hooks on cover. Slid e cover towardrear of vehicle and lower to ground.

(17) Loosen both clamps on eachwater outl e t hose on cylinder head and push hose down on elbow u ntilclear of radiato r thermostat housing. Working under vehicle, disconnect lowerhose a t radiator end of water pump inlet tube.

(18) Worki ngthro ug h bulkhe ad sliding door openin g (fig. 6 4) or from under ve

hicle, remove hairpin lock and clevis pin that hold fulcrum lever toconnecting lin k on rear relay (fig. 65) .

GENERATOR C RADLE(GENERATOR REMOVED)

(INSTALLED! V

R . H. ENGINE*Hl l j j&>

RA PD 33194^1

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(19) Working through bulkheadsliding door opening or from under vehicle, remove two cap screws,one on each side, for the engine front support bracket on trans missio n.

(20) Remove conduitfrom generator termi nal by unsnapping wire clip from cover. Lift off

cover. U n s crew conduit connection at bottom of wire shield box. R e-move n uts and washershold ing wires to terminals (fig. 66 ). Li ft wiresoff terminals and pull wires ou t of box. Disconnect starter feed cableat battery terminal block on rear hull plate by removing cover, removing nut fro m stud, and lifting off cable.

(21) Refer to paragraph(22) Removetw o cap screws, one

on each side, from engine re ar support brackets.(23 ) A ttach engine sling (41- S-3831-3 00) to

chain hoist and connect to liftin g rings on each cylinder head. Raiseengine with ho ist until it is clear of engine supp ort brackets (fig. 67). S lid e engine toward re ar of vehicle u ntil splined shaft on univers aljoint at transmiss ion slides out of transfe r unit and splined sh aft onfan drive p ulls out of yoke. Tilt engine upw ard at rear just enoughso ge nerator cradle will clear rear hu ll wall; lift engine out of vehicleand place in s tand.

(24) If a new engine is bein g in

stalled, remove fa n universal jo int shaft assembly from replacedengine and install on new engine. Remove transfer unit in put shaftfrom t ransm ission of replaced engine assembly, and install on newtransmission.

68. Eng i n e Ins ta l la t ionEQUIPMENT. The only special equipment necessary for the in

stallation of the engine is the sling (41-S -3831-30 0) and a chain hoist.6. P RO C E D U R E .

Engines can be made fully in terchangeable, right to left, simply by reversing the exhaust connection.

(1) Place engine sling (41-S-3831 -300) on liftingrings on cylinder heads and connecthoist to sling. Ra ise engine aboveand slightly to rear of engine compartment. Lower engine carefullywith transmiss ion end tilted down. Line up blin d spline on fan shaftwith fan yoke. Guide transmiss ion universal joint yoke splines intotransfer unit input gear (fig. 68)-. Lower engine car efully until itrests on engine supp orts. Remove the sling. Tig hten packin g nuton fan-shaft yoke.

(2) Install two bolts, one on eachside , in engine rear support bracket s. Working through b ulkheadslidi ng door opening, in stall two bolts on f ront support brackets.

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(3 ) Kefer to pa ragraph 81

(4 ) Place feed cable overterminal on te rminal block on re ar hull pla te and rei nstall nut andwasher. Place cover gua rd over terminal block and fasten securely.Insert generator feed condu it wires through opening in coveron front

of generator and fasten leads to prope r terminals (fig. 66). In stallnuts and washers holding leads to terminal posts. Slide knurled n utupon condui t and fasten to bottom of box. P lace cover on box andlock in position with locking wire.

- (5 ) Place transmissionselector leverin "DRI VE" position. Position manual c ontrol rod inthe m iddle detent position. If the clevis pin hole in the bot tom of the fulcru m lever does not line up with the hole in the connect ing link,

loosen c lamp screw on adj ustable rod on transmission rear support(fig. 109 )and slide rod in or out until clevis p in holes line up. Tightencla mp screw and install clevispin and hairpin lock.

(6) Working under vehicle through rearhull floor opening, ins tall lower radiator hose betweenradiator andwa ter pump inlet tube. Tighten hose clamps. Working above engine, install bot h o utlet hoses betweenrad iator therm ostat housing andoutlet connectionson cylinder head. Ti ghten hose clamps securely.

(7 ) Line up prongs on engine feedcon duit w ith holes in plug. P u sh both ends of conduit together andtighten cou p ling nut.

(8) Slide end of tachometer cable intodrive gear in di stributor support and fasten cable to support withknurled coupling.

(9 ) Slide rubber gasoline hoseover endof ni pple at auxiliary fuel filteron carb uret or and tighten hose

clamp securely.(10) Place spr ings and washers on both

ends of throttle cross shaft and position cross shaft first in one br acketand th en in other b racket. Fasten br acket to intake manifold mounting studs. Connect lowerrela y rod to throttle cross sha ft lever andinstall clevis pin and co tter pin. Slide throttl e rod ball stud throughmounting hole in throttle cross shaft lever and inst all nut and washer.Adjust throttle li nkage as expl ained in paragraph H O e .

(11) Slide carbureto r air intak ehose over elbow at engine side wall. P osition other end of air intakeelbow on top of ca rburetor. T ighten hose clamps securely. Ins tallchoke thermostat ai r line at intake elbow and left exhaus t man ifold.Tighten coupling s at both ends. Ins tall distribut or ventilating airline at intake elbow and tighten coupling.

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-T R AN S F E R UN IT I N PU T S H A F T

T R A N S F E R UN IT JE NG IN E F R O N T

S U P P O R T CU SHIO NS R A P D 3 3 132 2

(1 2 ) L o w er muffler ass emb ly int o p os it io n

n ex t to eng ine co m pa rtm e nt sid e wa ll (fig . 6 1) . P os ition a new exh a us t p ip e ga ske t be tw een muffler and ex ha us t conn ect ion. In sta ll tw os cr ew s , nu ts, a n d was hers .

(13) In st al l dr ain p lu g in bo ttom

o f tra n sm iss io n an d in s tal l d rai n cover p la te . F il l co oli n g s y ste m w ithcoo la nt (a p pro xim ate ly 40 q u ar ts ). Ins tall radi a to r cap , m akin g sure

g as k et is in go od con d iti o n.

C aut ion: W he n sys tem is filled wi th co ld w ate r, i t ma y be n ec es sary

to run th e en gi n e u n til the rmo stat val v e o p ens a n d p e rm it s syste m tobe com p le te ly filled. B e sure to do this i f syste m takes le ss th an 40q ua rts. In spe ct co ol in g sy ste m for leaks and co rre c t if an y ar e fou nd.

(1 4) R ef er to p ara g ra p h 11 0 & .

(15 ) R ef e r to pa ragr aph 73.(16 ) S et the b rake s.

R un b ot h eng ine s a t sam e ti m e w ith tr a ns fer u ni t in H IG H and t rans mis sion le v er in NE UT RA L. Se t h a nd thro ttle to run engi n es at 1,000re v olu tion s per mi nute , a n d move se le ct or le v er sl ow ly to wa rd D R IV E .By w a tch ing tac hom ete rs, n ote pos itio n of lev er wh en s p eed of one engi ne d rop s. Re ar edge of sele cto r lev e r s hou ld be a pp rox im a te ly

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one-eig hth inch in fron t of front edge of slot in quadrant when enginespeed drops. Continue moving le ver until speed of othe r engine dro ps.This shou ld be within one -eighth inch ad ditional le ver travel. Ifdifference is greater, readjust fulcrum lever of newly insta lledtransmission (par. 121).

(17) Coat edges of floor platewith gasket paste, and place ga sket on plate. Raise front edge o f plat euntil h ooks on plate rest on hull floor. Raise rear end of plate, andline u p screw holes with two drift punches. Install floor plateretaining screws.

(1 8) Place engine compartmen t rear plate in position and install four atta ching bolts (fig. 59).Place engine compartmen t cover over openi ng a t rear of engine com-

.partment and instal l four attaching bolts (fig. 59).(19) Slide exhaust pip e exte nsion

th rough extension shield and into muffler outlet elbow (fig. 60) and in s tall attaching screw at outl et elbow. Ins tall exhaust pipe extensi onrear suppo rt bolt at extension shield and tigh ten securely (fig. 60).

CONDUIT CONNECT ION

DISTRIBUTOR

PRIMARY TERMINAL (LOW TENSION)

SECONDARY TERMINA L (HIGH TENSION)

FEED WIRE

FROM

RESISTOR

WIRE MARKER SPARK P LUGS COIL RESISTO R FEED WIRE R A PD 331802

Figure 69 . Engin e showing ignition units.

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(20) Positio n engine co m partment doors overo penin g m ak ing sure piv ot at fron t edge of door isli ned up w ith angle bracket. P lac e rear angle brack et in position a n dins tal l two atta chin g bolts (fig. 49). Open and close doors to see thatdoors open and close with out bind. Close doors and tu rn la tch han dles

to locked position.

Sect ion XVIII. IG NITION SYSTEM

69 . Desc r ip t io n an d D ata

DESCRIPTION. T wo iden tical, but completely ind epende nt ig niti o n systemsa re used, one for each engine. Eac h complete igni tionsyste m is shielded for w at erproofing and to provi de effectiveshielding agai ns t ra dio inte rfe rence. E ach system consists of an ignitioncoil mounted on a b racket on the center of the ri gh t cy linder h ead (fig . 69); a timer inside the distr ibu tor housi ng ; a condense r, alsolocate d inside the distri but or housing; a distrib uto r which dire ct s thehig h volta ge to each of the spark p lug s; the sh ielded wa ter proof, two-piece spark plugs ; and the necessary shielded metal -c lad wirin g toconnect the ign ition units . T he wir ing circuit diagr am of the ig nitionsystem is shown in figure 38.

6. D ATA . (1 )

Con tact poin t g ap__ ___ ____ ___ __ 0.013 to 0.018 in.Con tact spring t ension_ __ ______ _ __ 19 to 23 oz .D irection of rotation (f rom top) ___ ____ C lockwise.Model nu m ber____ __ ______ _ ____ D K -1110612 .Tim ing ad jus tment— _— ——_ ___ __. Eota te on mount in g.

(2)

A m perage dra w, at idling sp eed__ __ . 1 1 / 2 amp.Model nu mber__ _ ______ __ ______ DR - 1115281 . Vol tage _____ ___ ____ ____ ____ _ 24.

(3 )

Capa ci ty____ __ ______ __ ______ 0.18-0.23mfd.M ode l num b er_____ _ _..____ __ ___ D R-1900272 .

(4)

Gap __ _____ __ _____ __ ______ _ 0.028-0.033 in .Model numbe r_ ______ _ ______ __ _ A C-104 (waterpro of ).Number used __ ______ __ ______ __ 8 per engine.Threa d __ ____ ___ ____ ___ ____ _ 10-mm.

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DISTRIBUTOR

DISTRIBUTOR VENTILATOR LINE DISTRIBUTOR SUPP OR T

Figu re 70. Re movi ng distr ib utor.

L O W TE N SION

LEAD A N D

T E R MIN AL

- LA MP AR M

R A PD 33 1801

SCR E WDRIVER

BREAKER AR M

E CCENTRIC S C R E W

LOCK S C R E W

OIL W ICK

TIME R CAM

IGNIT IO N

CONDE NSE R

DWE LL ANG LE 25 °

.013- .018 " GAP - « ^^^ ^ ^^^ M BB ^M H B R A PD 331 80 3

77.

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70. Dis t r ibu to r A s s e mb ly

R E M O VAL. Open engine co mpartment hin ged a ir outlet d o or.Remove di stribu tor cap by loosen ing clamp screw on se aling ban d ,allo w band to drop , and lift distributo r cap off distrib u tor.

It is not necessary to discon nect wires unle ss cap is to be replaced.Disc on nect the two d istributor housin g venti lating pipe s. One of

the se pipes is conne cted to the cra nkc ase ventilating a ir cl eaner andthe other to the carburetor ai r inlet elbow. D isconnect the prim ary(low te nsion) w ire by unscrewing the cou pling at side of dist ributo rand also d isconnecting the end of wire ins ide the distributo r at thete rminal (fig. 70).

The lea d from the condens er connects to the same terminal.

Re move cap screw ho lding d istributor clamp arm to the su pport base,and lift out dist ributor assembly.

INSTALLATION. Posit ion comp lete distributor assembly in suppor t, tur ning rotor un til lug in lower e nd o f shaft meshes with slot indi stribu tor drive shaft. Install cap screw ho lding clam p arm to baseof d istributor suppor t. Conn ect prim a ry (low te nsion) w ire by in serting end throug h coupli ng fitting and connecting lead to terminalin distributor.

Co nnec t condens er to p rimary ter minal at same time prim ar y connec tion is made.

19-2 3 OUNCES

SPRING SCALE

BREAKERARM

RA PD 331804

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Tigh ten knurled cou pli ng nut at distr ibu tor housing only finger-tig ht. If pl iers are used, too much press u re may be applied and sealsat end of wire may be damaged. If wires were removed from top ofco il or distrib utor cap, reinstall and tighten finge r-tight.

Cau tion : Pliers must not be used. The m etal shell on distr ibu tor

cap may be distor ted or the high-te ns ion towers on the bakelite capcracked. Keconnect th e tw o dis tributo r housing v entilating pipes a ndtigh ten securely. In st all d istributor cap. Place s eal ing band inp osition and tigh ten clamp screw. If high-ten sion wires were disconnected from distributor cap, reconnect wires fro m coil and spa rk plugs. C heck and readjust ignitio n ti ming ( par. 7 3). Close enginecompar tment air outlet door.

C O N T A CT P O I N T S . (1 ) Co ntact points a re acces

siblefor

service whenth e distr ibutor is e ither on or off th e engine,

in or out of th e vehicle. F igur es 71 an d 72 show operations bein g performed on the bench; however, the work may be performed in thesam e manner in th e vehicle. Remove distributor cap and rotor toservice con tact points .

(2 ) The appearanc e of contact poin tsrevea ls whether the po ints requi re any service at all and w hether th eyshould be cleaned or replaced. Co nt act point appeara nce can be classified as fol low s:

A rough gr a y surface on the contact points is an ideal condi tion. D o not clean or replace poi nts with this appe arance.

O il-soaked p oints usually do not require dressing. C lean pointsthor oughly, an d then see that th e source of oil lea kag e is det ermine da nd corre cted.

Pitted conta ct p oints will not cause ignition fa ilure unless th epitting is severe. D o not replace points because of minor pits or pro jections. Remove, clean, and smooth u p wit h a carbo rundum stone.

O xidized p oints which have a blue or black scaleu sual ly do notrequ ire replacement, b ut the scale must be removed. Oxi dized pointsa re usually caused by a faulty coil o r condenser. R eplace these unitsif th e oxidized conditi on recurs freque n tly.

(3 ) If points are ba dly pitted, burne d,or worn, remove and dress car efully with a poin t dresser until all trace of corrosion or pitting is removed, k eeping the su rfac es as square aspossible. Make sure that the po ints line up sq uarely with each otherand readjust ga p. Retime igniti on.

Caut ion: N ever attempt to clean points with emery cloth or sand pa per.

(4) Turn distrib utor d rive shaft un til cam is holding points at widest opening. Loosencontact suppor tlock screw with sc rewdriver, and adjust poin t open ing to a clearance of 0.013 to 0.018 inch (0.015 in ch is ideal) by tu rning eccentric screw144

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(fig. 71) and checking clearance with feeler gage. Ti ghten lockscrew a nd recheck clearance to make sure that points remaine d inadjustmen t.

(5 ) Check ten sion o f cont actarm spring w ith spring scale hooked over arm as close to poi nt s as

possible and held at right angles to arm (fig. 72). Correct te nsion to19 to 23 ounces. If spring scale is not available , check tension by feel.Tension can be adjus ted by loosening screw on break er supp ort fiberbase and sliding the spri ng either forwar d or back ward, or b endingsprin g .

(6) Remove lock screw from conta ct armsupport (fig. 71). Loosen screw holding contac t arm spring to connector. Remove re tainer from contact arm suppor t stud. Lift ou t

break er lever an d con tact point suppor t. Place new pa rts in position, reinstal l mounting screws and retainer, and adjust gap.• S ee that fiber rubbing block on contact a rm is parallel to d istributorcam.

Install rotor and distributor cap. Retime ignition .C aution : Wipe new pa rts completely fr ee of any oil w ith which

they have been coated for pro tection.

71 . Co il

RE MO VA L . O p e n engine compar tment hinge d ai r outlet door.D isconnect the primary and secondary wire fr om top of coil by unscrewing the coup ling nuts on the shie lded wire. D isconnect the feedwire from the resis tor at the bottom of the coil. R emove tw o cap screws and lock washers th at attac h coil to mounting brac kets and remove coil.

Ignition coils can be serviced only by replacement of th e complete unit.

I N S TA L LAT I O N . Positio n coil on mounti ng brac ket and attachsecurely with two cap screws and lock washers. Connect prim arycond ui t (low tension) to minus tower and secondary con duit (hightension) to ce nter tower on to p of coil. Tigh te n knurled cou plingnuts only fin ger-tight.

Ca ution: Pliers mu st not be used. I f pliers are used, too much pre ssure ma y be applie d and coupling nuts and seals at end of conduit s

will be damaged. Connect feed wire to resistor terminal at bottom ofcoil (fig. 69 ).

72. Co n d e n s e r

R EM O VAL . O p e nengine com partme nt hinged air out let door. R emove distri butor cap and r otor. D isconnect condenser lead from

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primary wire terminal (fig. 71). Remove screw and lock washerholding condenserbracket to breaker plate and lift out condenser.

Ignition condensers are serviced by replacementonly.

I N S TA L L AT I O N .Position condenser and bracket on breaker plateand attach securely with screw and lock washer. Connect condenserlead to primary terminal. Install rotor and distributor cap.

73. Timing A d j u s t m e n t

M E T H O D .The correct method of timing ignition is by use of asynchroscope or a timing light.

f t . P R O C E D U R E .(1 ) Warm up engine until a smooth idle of 450 to475 revolutions per minute can be maintained.

(2 ) Stop engine and open engine compartment air outlet door.(3 ) Remove four screws attaching generator and oil filter access

plate to engine compartment cover and remove access plate (fig. 59) .(4 ) Disconnecthigh-tension conduit at N o. 6 spark plug by loosen

ing coupling nut at plug. Connect spark plug lead from timing lightto the spring terminal at end of the insulator on the spark plug conduit. Connectthe electrical feed lineof the timing light to the resistorterminal at the bottom of the coil, and to any good ground point such

as the exhaust manifold stud (fig. 73).Caution: Do not connect a 12-volttiming light to resistor terminalat bottom of coil. If a 12-voltlight is to be used, it must be connectedto one battery only, to prevent burning out the light due to highvoltage.

(5 ) Restart engine and run at a smooth idling speed at 450 to 475revolutions per minute. Holding handle of timing light, aim light atpointer on engine front cover. Light should be aimed, and readingshould be taken as directly over pointer as accessibilitywill permit.The timing should be se t so that pointer indicator on front cover linesup with IG/A mark on the crankshaft pulley.

(6) Adjust timing by loosening clamp screw on distributor arm andturning distributor until IG/A mark on crankshaft pulley lines upwith pointer on front cover. After proper setting has been obtainedtighten clamp screw securely (fig. 73).

(7) Disconnect timing light and reconnect spark plug conduit.Tighten spark plug conduit coupling nut finger-tight, plus approxi

mately one-half turn using a small wrench.Do not force coupling nut.

(8 ) If detonation is heard with above setting, it indicates that thefuel used is of less than 80 octane value and the spark should be retarded to the barely audible detonation point. It is preferable, however, to obtain correct grade of gasoline.

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NO. 6 SPARK PLUG C O NDUIT TO TIMING LIGHT

TIMING LIGHT FEED WIRE

TIMING LI GHT CONNECTIONS

GROUND

CLAMP S CREW

HOLD-D OWN SCREW

DISTRIBUTORMARKER PLATE

IS ETTING TIMING

RAPD 33 18OO

(9 ) Above ti ming procedure applies to e ither right or left en gines.Bot h engines should be checked whil e timi ng facilitie s are available.If a synchroscope or tim ing lig ht is no t av ailable, the tim ing can bese t in the following manner: Conne ct a 24-volt lamp across the ig nition points. Crank the engine by hand using a socket wrench on thec rankshaft pulley screw until the IG/A mark on th e pulley lin es u p

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with the pointer on the front cover. Rotate the distributor until thelight just goes Tighten clamp screw on distributor arm. Thismethod should not be used except when other facilities are notavailable.

(10) Position generator and oil filter access plate over opening atrear

of enginecompartment and install four attaching screws (fig.59) .

Tighten screws securely.(11) Close engine compartment air outlet door.

74. Wiringa. R E M O VA LO FC O M P L E T EIGNITIONWIRING. Open engine compart

ment hinged air outlet door. Disconnect spark plug high-tensionconduits by unscrewing coupling nut at upper portion of spark plug.

Disconnectconduits at distributor cap by unscrewing knurled couplingnut at each conduit. Remove screws at straps on the conduit supports,loosen straps, and remove wiring.

& .INSTALLATIONO F C O M P L E T EIGNITIONWIRING. Connect each ofthe spark plug conduits in turn to the distributor cap, working fromthe wire markers and following the order indicated (fig. 74).

There is a numbered disk, placed on top of the distributor cap throughwhich conduits pass.

7 .} .

Install conduits on support straps and connect to spark plugs.Tighten spark plug conduit coupling nuts finger-tight plus one-halfturn with small wrench. Donot force coupling nuts. Tighten screwsat conduit support straps and connect primary and secondary wiresbetween distributor and coil (par. 71).

INDIVIDUALWIRES. Replacement of individual wires can beperformed by using the foregoing procedure as a guide.

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pre ssure b u ilt up in the rotatin g trans m issio n w ill keep th e warn ingsign al swit ch ope n a nd th ereby leave th e rel a y wi th no g ro und conne ction . Whe n ever th e engi ne sto p s a nd tr ansm is sion oil p re ssure dro ps, the switch closes mak in g the g ro und conne c tion. The cir cu itcan th en be co mp leted b y pre ssing the s tar ter but to n.

DATA .St arte r:

M ake— ___ __ ___ __ ___ _ ____ _ __D el co-R e my.Mode l No. _ __ ___ _ ___ __ ___ _ ___1 1 085 68 .Type—— — — —— — —— — — —— — —._—_———.Four-pole, com pou nd .V olta g e___ _ ___ __ ___ _ ___ __ __. 24 .

7 7. S ta r t e r

RE M O VA L. (1 ) O pen ma ster ba t tery swi tche s b y pu llin g out on knob and tu rn abo ut one -quarte r turnto lock in open positio n.

Rem ove star ter only after te sts ( par . 42) ind icate th at this unit is a tfault.

(2) Rem ov e scr ew s fr o m lef t hu llfloor plat e. S u ppor t rear end of pla te wh ile r emo vin g la st screw s to

SOCKET ON UPPER IGNITION COILSTARTER -A MOUNTING SCREW FEED WIRE (212-12 )

RA PD 35 38O 2

THROTTLE LOWER RELAY SOLENOID LEAD -/ •'-BATTERY FEED(274-7 4)

75 .

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R.H. STARTER RELAY RELAY SUPPORT ATTACH ING SCREWS

AMMETERSHUNT

APPARATUS BOX(COVER REMOVED) L . H . ST A R T E R R E L A Y R A PD 331819

prevent plate from dropp ing down and cau sing injury. Front of plate is h eld up by hooks. Slide plate toward rear of vehicle and lowerto ground.

The starters of both enginesare accessible through the left hull flooropening.

(3) Removenut from batt ery feed cable and lift cable off terminal. Disconnect wire from starter solenoid by removing nut and lifting off terminals.

(4 ) F irst remove upper mounting screw (fig. 75)wh ich passes through flywheelbell housing; then remove bottom screwwhile suppo rting we ight of star ter with other h and. Removestarterthrough hull floor opening.

6. I N S T A L L AT I O N .(1) Reaching up through lefthull opening, place starter in position in op ening on flywheel h ousingso th at dowel on housing fits into cut-out on starter flange. Whileholding motor in positio n with one hand, install lower mounting screw

through flywheelbell housing and tighten screw. Insta ll and tightenot he r screw.(2 ) Connectsolenoid switch wire and also

battery feed cable to starter, and install retain ing nuts and washers.(3) P lace gasket in position on rear

hu ll pla te. Raise front end of p late and place hooks on plate over edge

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of h ull floor. Kaise rear end of plat e, aline screw holeswith driftpunch and install attaching screwsand washers.

78. Star te r SolenoidE E M O VA L .Remove solenoid only after tests (par. 42) ind icate

that this unit is at fault. Eemove starter (par. 77). Removecott erpin and lever pin h olding solenoidplunger link to sta rter clutch actuatin g lever. Removefour mounting bolts holding solenoid to st arter.Remove bolt holding g round strap to starter. Remove lead wires.Lift solenoid off starter assembly.

I N S T A L L AT I O N .Place solenoid in position on star ter and installfour bolts. P lace clutch operating lever in posit ion and lock w ith newcotter pin. Install lead wires on solenoid.

79. Star t ing RelayRE M O VA L .Remove relay only after tests (par. 4 2) indicate that

this unit is at fault. Open master battery switches. Removeeightscrews and take off apparatus box cover. Disconnect five wires fr omrela y terminal. Remove tw o hex n uts, washers, and screws, andremove relay assembly from mounting bracket in app aratus box (fig. 76) .

6. I N S T A L L ATI O N . Positio n relay on bracket in ap paratus box andinstal l hex n uts, washers, an d screws, w ith ground wire inserted und erinne r screw. Reconnect five wires to relay according to diagram(fig. 37). Install appa ratus box cover and secure in place with eightscrews.

Section XX. GENERATOR A ND C H A R G I N G SYSTEM

80. Desc r ip t ion a n d DataC H A R G I N GCIRCUIT. Since there are tw o generators , one on each

engine, the re are two ide ntical C harging cir cuits, each connected so asto cha rge both bat teries. Each charging circuit consists of a generato r,a fo ur-unit gener ator reg ulator, and th e cables and conduits requiredto connect these unit s to the batteries (fig. 39).

G E N E R AT O R S .Two generators are used, one moun te d on each engine. Eac h generat or is a 24-volt, 50-ampere,4-brush, 4-pole, sh unt-wound type, with sealed, self-lubricated ball b earings supporting thearmature. The g enerator is clamped in a mo unting cradle and brac ket,an d driven from the cranksh aft by three matched belts. The cradleis adjusta ble to provide correct bolt tension.

G E N E R AT O RR E G U L AT O R S. T he tw o generator regulators aremounted in the apparatus box on the fro nt of the bulkhead (fig. 77).

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Each regulator consists of four units: a voltage regulator, a currentregulator, a circuit breaker relay, and an actuating relay. These lasttwo relays function together to perform the same duty as a cut-outrelay; namely, to open the circuit when generator voltage falls belowbattery voltage, and to close the circuit when generator voltage is suf

ficient to charge the battery.D ATA .

Generator:Model No_____________________ DR-1117309.Output, cold_________—__—_____. 4 8 to 50 amp.Rotation, drive-end view___________ Counterclockwise.Winding____—__—______—_—_— 4-pole, shunt.

Generator regulator:

Model No______________________. DR-1118501.Type________________________. 4-unit, 24-volt.

81. Generatorsa. REMOVAL. (1) Make certain, by following the

test procedures given in paragraph 46, that generator requires replacement.

(2) Elevate howitzer to provide clearance between gun and top of hull. Remove four screws attaching access plate over generator and remove plate (fig. 59). Open masterbattery switch. Turn handles to unlocked position and open hingedengine compartment doors.

(3) Loosen generator cradle adjustingnut and allow generator and cradle to drop to lowest position. Loosenknurled packing nut on front fan-shaft yoke at generator pulley end.Slide three drive belts off generator pulley.

Caution: Never pry belts off pulley with a screwdriver or othersharp tool, as pulleys may be accidentally nicked and burred.

(4j Remove two nuts and spacers holding generator mounting strap clamps to cradle clevis (fig. 78 ) and swingclamps back. Remove conduit guard and disconnect generator cables.Lift generator out of cradle.

INSTALLATIONS.(1) Lift generatorinto mounting cradle on engine, at the same time sliding fan shaft inrear of generator pulley into universal joint yoke splines and seating

locating lug on cradle in locating hole in generator housing (fig. 79).Swing generator strap clamps into position on generator and insertclevis in toggle. Install spacer and nuts on clevis and tighten. Reconnect generator cables (fig. 66) and install conduit guard.

(2) Lift each belt in turn up into itsposition on pulley. Tighten knurled packing nut at front fan-shaftuniversal joint yoke. Raise generator and cradle until there is %- to

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A P PA R ATUS B OX (COVER REMOVED) NO. 4 RED (4) -\ fJ O. 6 B LACK (4)

J UMPERNO. 6 B LACK (202)NO. 14 NAT. 2//GR.TR. (201)

R. H. REGU LA TOR

REGULATOR MOU NTING STUDS

J U M P ER J \\ '"N O.N O . 6 BLACK(4) A \14 NAT. 2//

N O . 6 BLACK (2)- G R.TR. (1)

L . H. REGULATO R

RA PD 331842

77.

% -inch slack in the belts, measured midway between g enerator andwater pum p pulle ys (fig. 5 0).

(3) Re install gen erator access pla te.Close engine compartment doors and turn ha ndles to locked position.

82 . G e n e r a t o r Regulators

R E M O VA L .M ake certain, by followi ng test pr ocedures given inparagr aph 46, that gen erator regulat or req uires replacement. Openm aster battery switches. Remove appar atus box cover. Remove sixnuts (fig. 77) that hold regulator mou n ting assembly to app aratus

box. Pull ge nerator regula to r assemblieso ut of app aratus box. Remove fou r bolts holding regulator to mo u nting bracket. Disconnectthree wires at regulator termin al s and remove regulator.

I N S TA L L ATION. Connect three wires to reg ulator termin a ls, asshown in figure77. Close master ba tt ery switch, and connect a jumper wire mom entarily between "G enerator" te rminal and "Ba ttery" te rmina l of regulator. T his allows a mom enta ry surge of bat tery cur: entto flow to the gene rator and polarize it corre ctly . Position re gulator

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F AN S HAFT P AC KIN G N U T M O U N T IN G STR AP S

CO N D U IT G UARC

DR IVE BELTS (MATC HE D SE T)

A D J U S T I N G R A P D 3 31 3 0 1

GENERATO R.

LO C AT IN G HOLE

AD J UST IN G NUT-

CRADLI

CL AM P S CREW

L U G— '

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assembly on mounting b racket and insta ll fo ur mountin g bolts. Pl aceregulator assemblies in appara tus box and ins tall six nut s ho ldingregulato r mounting br ac ket assembly in box. Install ap paratus box cover (fig. 77) .

Never attemp t to readj ust generator, regulators; service by replace

ment only.

Sect ion XX I. BATTERY AN D LIGHTING SYSTEM

8 3. Des cr ipt ion a nd Data

B AT T E R Y. (1 ) A 24-volt electrical system is employed. The battery consists of two se par ate 12-volt, 6-cell units, mount ed one on each

side of the vehicle , in a compart m ent in the hull just above the frontend of the fue l tank (fig. 80).

(2) The two ba tteries, one on each side, are connected in series top rovide the 24-volt potential. T he circuit of the battery system isshown in figure 39.

M A ST E R B AT T E R Y SW ITCH. The m ast er ba ttery switch, located ina box m ounted on the le ft side of th e engine bulkhead between the air cleaner and hull side wall (fig. 5 ), is provided to open the batte ry

ground circ uit and thus cut off all electrical c ircuits.BAT T ER Y O U T L E T.T he battery cha rgin g outlet is located in thesame box as th e master switch (fig. 5). This outlet provides forp lug ging in a slave cable to anothe r vehicle or to a battery charger when th e batt eries are too low to function pr operly. The cir cui t isshown in figure 39.

L I G H T IN G S Y S T E M. (1) T he drivin g lightsconsist of two h eadlights, w it h blackout ma rker lights incor por ated, ablac kout driving ligh t, and tw o d ual- purpose taill ight s. The left taillig ht con tains a b lackout taillight and a double filament c o mbinationservice ta il and stop light. The r ight tai llight contai ns a bl acko uttailligh t and a blackou t stop light.

(2 ) T he blackou t driving light w*hennot in use is carried in a brack et mou n ted on the left hull wall in back ofthe d river's seat, and is put in use by substituting f or the headlight in the left h eadlight mount. A resistor is in serted in the ci rcuit to reduce the volta ge to the l ight from 24 to 6 volts . This reduct ion in vol tage is necessary, due to th e special design of the blackou t drivin gligh t, in order to obtain the proper illum ination. The re sistor assembly is mou nted b ehind the instru ment pan el at the junction of theupper and lower deck of the hul l. This circuit is shown in figure 41.

(3) There are two lamps in the instrumen t pa nel that prov ide illumination for all th e inst ru ments. These lam ps are controlled by a rhe ostat switch located in th e upper left-ha n d

15 6

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MASTER SWITCH CABLE.AND G R OUND

BATTERY-CONNECTING CABLE

RADIATORFILLERCOVER-

BATTERYCOVER ANGLES

BATTERY-HOLD-DOWNCLAMP

FUEL VALVECONTROLCABLE

FUEL FILLERCOVER

corner of the panel. These lamps are availabl e by removal of theaccess plugs.

(4) T wo dome lights are provided, located in thedriving compartme nt o f the hull, one on the upper deck just aboveand forward of the assistant driver and the other on the bott om of theem ergency ignition switch box. Each dome light has two lamp s andtwo lenses (clear and red).

CIRCU ITBREAKERS. Se ven circuit breakers are in corporated inthe el ectrical sys tem in place of the conventio nal fu se arrangement.

The circuit breakers (exc ept those in the charging circuit ) a re all ofthe manual-reset type, which mea ns that the protected circuits can be closed again after the circui t breaker has operated simply by pr essing the reset button. The charging ci rcuit breakers are fully automa tic. T he various circuit breakers are located as follows:

(1) The circui t breaker for the driving lights is locatedin the lower left corner of the instrument panel (fig. 6).

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(2) The circuit breaker for the siren is also located in thelower lef t corner of the in strument panel.

(3) The circuit breaker fo r the fuel pumps is locatedin the cente r of the fuel pump switch bracket (f ig. 7).

(4) The circuit breaker for the ventilat or motor islocated on the ventilato r assembly, on the driver's side, toward thefron t of the vehicle.

(5 ) Th e circuit breaker for the hull dome lightsand the windshield wiper (cold-weather accessory) is located on thefront face of the emergency ignition switch box (fig. 12).

(6 ) Two circuit breake rs in generator armaturecirc uit are mounted one on each regula to r.

/. DATA. (1 )Type________ ___ ____________ 6-cell.Voltage— each-____—_——__——___ 12.Voltage—entire system ._—___—_—_. 24 .Number of batteries...— — — — —_ — — — — _ .2.Number of plates per cel l—————_——— — _ 17.

(2)T y pe___——___———_____— — —_ Single-pole, single-throw

(3)Si ren___-_ ____________— ___ 15 am p.Driv ing l ights______—————_—— —— — . 3 0amp.Fuel pump_—_____—____— —— _ 15 amp.Ventilato r_____________ _—___ 15 amp.Dome lights and w iper.—— ___———_ 15 amp.Generator..———___— ——_— ———_. 70 amp.

(6) Typ e, all except charging circuit._ Bimetal disk.Keset, all except c harging circuit__ Manual.Type, c harging circui t________ Automatic reset.

(4)B lackout marker light.———__——— —_ 3-cp single-contact.Taillight_—_____ —____—— —___ 3-cp double-contact.Blackout stop lights_—— ___——— _ 3 -cp.Service hea dlights_________ ———_ 40-watt.Type__________ __-___ __-_.—- Sealed beam.Service stop ligh t_____________ __ 21-cp double-contact.

Instrument panel light s—_—_—_____. 3-cp single-co ntact.Signal li ghts.._____ _______—__ 3-cp double-contact.B lackout taillights__— —— — — _ _ — —— — — .3-cp.Blackout d riving ligh t.-._____———_ 6-volt with resistor.Dome lights—_______-___ _—__ . 6-cp single-contact.Spotli ght, type______ ______ _____ Sealed beam.

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84. Bat te r ies

G ENERAL. The service which the us ing ar m can perform on tht>battery includes recharging or repl acement, replacing cables , addingwater, checking specificgrav ity, and cleaning.

& . C H E C K I NG BATTERIES. Never use matches or a flame as a lightwhen check ing the battery . Distilled or cle an water can be added tobring the fluid level just above the ba ttery plates. If the specificgravity of any cell is 1.200 or below, the battery sh ould be rechar ged.A fu lly charged battery should have a specific g ravity reading from1.275 to 1.300. Batteries can be charged in the vehicle by connec tingon outside sourc e to th e battery outlet. Master battery switch must beON whe n rechargi ng batteries by this method .

B ATTERYT E R M I N A LC O R R O S I O N .W arm water poured slowly overthe term inals will loosen any copper sulphate that h as bee n deposited,so that it can be brush ed off and flushed away.

Caution: Th is shou ld ne ver be done with th e battery in the vehicle.Batte ry pos ts and terminals should be wip ed clean with a cloth saturated in an alkaline solution, such as ammonia or a so lution of bicarbonate o f soda an d water. Corrosion can be retarded by applyin ga heavy coating o f general purpose grease (No. 1 ). If battery fluidhas overflowed or has spi lle d, all affected meta l parts should beflushed with a n alkaline so lution and wiped dry . K emove drain plateon bottom of hull under fuel tanks to allow water to dr a in from fueltank compartment.

REMOVING BATTERYC A B LE S . T he battery connector cable andmaster battery switch cable can be repl aced by the using arm in thefoll owing manner: Turn master b attery switch to OFF position. Remove batte ry box cover. Cover is held in p lace by a lever and camarran gement. Pul l lev er to relea se cam and slide cam and lever to

free co ver from latch.

It is not necessary to remove batt eries from vehicle to replace cables.

Remove battery ground cab le by remo ving nut holding cable tobattery post, and pulling cable into en gine compartment. Back offknurled nut attaching cable to the master switch box and lift out cable.Loo sen screws holding co nnector cable to posts on batteries, and remove cable from atta ching clips.

INSTALLINGBATTERY CABLES. In stall connector cable in clips onrea r of bu lkhead, and a ttach to battery po st on each si de (fig. 39).A ttach master switch cable to sw itch, thread cable through openi ngin bulkh ea d and conne ct to negative batte ry terminal post. Installbatter y box cover.

/. REMOVINGBATTERY. Tur n master battery switch to OFF po sition. Remove batte ry box cover. Cover is held by a lever and cam

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arrangement. Pull lever to release cam and slide cam and lever tofree cover fr om la tch. Removehold-down bolts and lift battery hol d-down out of position (fig. 80). R emove cables from battery postsby loosening bolt in connection. P lace cables out of position. Lif tbattery out of battery box and remove from vehicle.

INSTALLINGB AT T E RY . Turn master b a ttery switch to OFF position. Lift batter y into place in batte ry box. C onnect rear batterycables,following wiring di agram (fig. 39) . Install battery h old-downclamps.

Caution: Do not draw u p hold-down to o tightly or batt ery cellcovers may crack. Install battery connector cable and master b atteryswitch cable and tighten securely. Lift battery box cover into positionand lock with cam lever.

85. Mas te r Bat te ry Switches

G ENERAL. The m aster battery swit ch is located on a bracketmo unted on the engine bulkh ead at th e left rear corner of the drivingcompartment, between the left engine air cleaner and hull sid e wall.

& . R E M O VA L. Place mas ter switch handle in "OF F" position (fig. 5 ).Disconnect ground strap by removing bolt holding strap to hull side-

wall. Remove four bolts, tw o aboveand two below,that anchor bracketto bulkhead, an d pull bracket toward front of vehicle. Removenutholding cable and /or g round strap to terminals or ma ster batteryswitch that is to be removed. Removecable and tape end. Removescrew holding switch handle knob and removeknob. Removetw o boltsholdin g master ba ttery switch in positio n and remove switch.

INSTALLATION. Position switch in bracke t. Ins tall tw o boltsthrough brac ket and switch and tighten securely. R e m ove tape fromcable ends and install cables and /or g round strap on switch termin als.Place brac ket in po sition on bulkhead and insta ll four bolts, twoabove and tw o below. Install switch handle knob. Connect groundstrap to hull side wall.

86. Circu i t Breake r s

G E N E R A L. Inopera tive c ircuit breakers can be serviced by replacem ent only. They should not be disassembled.

When replaci ng circu it breakers, be sure master b attery switch is inO FF position.

R E M O VAL . (1 ) Removefour screws holdi ng domelight in positi on on emergency ignition switch box and lower domelight and bottom cover of box (fig. 12). R emove tw o screws holdi ngcircuit breaker in position in bo x; remove circuit b reaker and d isconnect wires.

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(2) Remove fou r nuts holding control assembly tomounting bracke t. Lower assembly to obtain enough clearance to disconnect the tw o wires and remove tw o screws hol din g ci rcuit brea ke rin the assembly. Remove circuit breaker.

(3) Remove ins trument panel (p ar. 89). Both

circuit breake rs are now accessible and can be removed by rem ovingtwo mounting screws for each an d then disconnecting wires from term inals.

(4 ) Remove two mountin g screws. Remove both wiresand remove circuit breake r from assembly.

(5 ) Remove regu lator term inal cover. Disconnect tw o leads and remove tw o screws and washers holding circ u itbre aker to top of reg ulator box (fig. 77).

I N S TA L L AT I O N . (1) Ins tall wires on c ircuit br eakertermina ls and tighten securely. Install two m ounting screws holdingcircuit breaker in positio n on emergency igni tion switch box. Placedome ligh t and bo ttom cover in po sitio n on box and secure with fou rscrews.

(2 ) Install wires, lock washers, and screws on cir cuit break er. Place circui t breaker in posi tion on control assemblyan d install tw o moun ting screws. Posi tion cont rol assembly on moun ting brac ket and install fo ur nuts.

(3) Install wires, lock washers and screws an dtig h ten securely. Place circuit bre aker or breakers in po sition onpanel, inst all tw o mountin g screws. Install inst rum ent panel (pa r. 89).

(4) Install wires, lock washers, and screws. Po sitio ncircuit b reaker on ven tilator assembly and install wit h two screws.

(5) Position circuit breaker on top of regulato rbox and in stall two screws and washers. Connect sh ort lea d fromregulator to rig ht-han d termina l, and lead from gen erator to le ft-

ha n d terminal (fig. 77). Install re gu lator termi nal cover.87. Lights

a. G E N E R A L .All ta illight and he ad light assemblies are compositeassemblies of lamps, lenses, and reflectors and ar e sealed against dirtan d moisture. The refore, the only service operation on the lights isre placement of the sealed assembly. The complete headli ght assemblies can be removed for saf ety in combat zones. Service o pe rationson the ligh ting switches are covered in p aragraph 101.

J . R E M O VA LO F C O M P LE T EH E AD L I G H T. To remove the headligh ts,turn lock ing handles inside hull to the lef t to loosen. Back off knurle dnut on lighti ng con du it. Remove co nduit from head li ght assembly.Lift asseinbly out o f mou nting.

I N S TA LL AT I O NO F C O M P L ET E H E A D L I G H T.See that light switchon instrumen t pa nel is "OFF". Place headlight in position on hu ll

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MARKER LAMP SOCKET

LIGHT BODY

BASE

HEADLIGHT BODY

HEADLIGHTRETAINER

BLACKOUT MARKERLAMP

MARKER LIGHTDOO R

RETAINING RING

-HEADLIGHTDOOR

HEADLAMP UNIT

HEADLIGHTSLEEVE PLUG

RA PD 331307

Headlig ht

front plate . Sec ure in pos ition by turn ing locking handle . Place

ligh ting conduit in p osition an d ti ght en knu rled nut securely.R E MO VA L O F HEADLIGHTSEA L E DU N I T. R emove screw ho lding

headlight do or to headligh t b ody (fig. 81) . S wing lo wer end of door outw ard and lift door from b ody. Pu ll sealed unit ass embly outwarduntil ter minal screws ho lding wires to sea led uni t assem bly can berem ove d. Disco nnect w ires and remove se aled un it assem bly.

INSTALLATION O F H E A DLIGHTS E A L E DUN I T. Connect red w irein headl ight b o dy to terminal on center of se aled unit assembly. Con

nect bla ck lead in headl ight body to sea led unit assembl y. Posi tionheadl ight door body b y insertin g lug on top of door th rough slot intop of body. Install screw hold ing headl ight do or to body.

/. R EMO VA L O F COMPLETE TA I L L IG H T ASSEMBLY. Re move threescrews holding base of taillight assemb ly to hull. Turn taillight assemb ly over and remo ve tw o nu ts and lock wash ers holdin g body tobase. Slide base away from b ody, and discon nec t both wires fro mbody by turning and pu lling connection s unt il they slip o ut of plugs.

INSTALLATION O F COMPLETETA I L L I G H TASSEMBLY. Conne ctwires to tai llig ht by inserti ng wires in sockets, an d turning the m sothat they w ill be lo cked in pla ce.

Be su re to conne ct wires to right so ckets to assure pro per operati on oflighti ng system. Refer to wiring diagrams , figu res 40 and 41.

Slide ta illi ght base on body and inst all two nuts and lock w as hers.Positio n tai llight on hull and ins tall three scr ew s holdin g base to hull.

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A. R E MO VA L o r TAILLIG HT L A M P S . Remove tw o screws hol d ing taill ight do o r to ligh t body and p u ll door off body (fig. 82). O n ri g ht- ha nd tai lligh t, p ull the ri ght blac kou t lam p fr om the lower po rt ion o fth e bo dy and th e b lac k out stop lamp from the up p er po rt io n of th ebody. These are sealed assemblies. On le ft-h a nd tai lli gh t, remove

th e b lac k out lam p fr om the lower po rt ion o f the body an d the servicetai l and stop lam p from th e upp er po rtio n o f the body.I N S TA L LA T I ON O F TAILLIGH T LA MPS. O n ri g ht- h an d ta ill ig ht ,

p osit ion th e b la ck o ut ta il lam p in lower po rtion o f body and th e blac kout stop lam p in the u pp er p orti on of th e body. On lef t-h and tail- li g ht, p o siti o n the black out tai l lamp in th e lower po rt ion in the body and the service tai l and stop lamp in th e up pe r p ort io n of the body. Po sitio n ta illig ht d o or on body an d in s tall two mo u ntin g screws an d

lock washers.R E P L A C E M E N T o r D O M E LIG HT LA MPS. Remove two screws hol din g dome light door, an d li ft off door, rubb e r gaskets, an d b oth lenses.Replace lamp. R ein s tal l door, gaskets, and lenses.

BLAC KOU T S T O P LIG HT UN IT

T AI LL IG H T BO D Y

TA IL LIG HT

B OD Y

S E R VICE S TO P AN D

T A ILL IG HT U NIT

T AIL LIG H T

D O OR

B LAC K O UTTAIL LIG H T U N IT

TAIL LIGHT D O OR

BLA C K OU T TAIL LIGHT U N IT

I. H . TA IL L IG H T

RAP D 3 313 0 6

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Sec t ion XXII. INSTRUMENTS AND INSTRU M E N T PA N EL88. Des c rip t ion

Th e ins trumen t pane l is m ounted in th e dri vi ng compar tm entdirect ly ahead o f th e driv e r. I t ca rri es the f oll owing instr uments and control s: tw o igni tion switches, tw o star ter button s, tw o tempe rature gages, two engine and tw o trans m ission wa rning signa l ligh ts,two tachom et ers, a speedometer, an ammeter, the m ain l ighting switch,the pane l-ligh t switch, circuit- bre aker res et buttons for the light s andsire n, and an outlet for connecti ng auxiliary electrical equipment.

6. D ia gnosis inf ormation on all elect rical instrum en ts is given inthe section on trouble shooting (p ar . 47). R epla cement in struction son the dia l in strumen ts appear in par agrap hs 90 throu gh 93; on thelamps i n paragrap h 93; on th e circuit br eakers in p aragraph 86; onth e switches in parag rap hs 98 throu g h 102; and on the complete pane lin parag ra ph 89.

89 . Instrum ent Pane l

R E M O VAL . Open master b a ttery switches. W o rking from dri ver's seat, remove cap screw and lock washer at lower cen ter moun tin g brac ket. Remove tw o screws and lock washers at upper centerm oun ting bra cket, a nd one at u pper right brack et. Loosen up per le f tmo unt ing screw, slide pa nel and br acket assembly to the left, andpull forwa rd. P lace p anel face down in la p, disconnect three flexible cables to speedometer and tachometers, and six flexible electric a l conduits. Remove panel from vehicle.

I N S TA L LAT I O N . Re install thr ee flexible cables for speedomete ran d tac ho meters. Reconnect six electri cal conduits (figs. 84 and 85),m aking cer tain that plugs are corre ctly indexed. Po sition pan elag ains t and to the left o f tapping blocks on h u ll front pla te and slide to the r ight, engag ing the slot at upp er le ft bracke t b ehind flat w asher and lock w asher of mounti n g cap screw. Install rem aining capscrews; two at u ppe r center bra cke t, one a t upper rig ht , and one a t

lower center. Tighten all cap screws securely.90. A m me ter

R E M O VAL . Remove instru men t panel fr om vehicle (par. 89).Remove tw o terminal nu ts (fig. 85) and disconnect lead wires fromammeter. Remove tw o m oun ting nu ts from term inal studs, slidem ounting clamp off studs , and remove amm ete r from fro nt of pa nel.

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INSTALLATION.Position ammeter in opening in panel and installmounting clamp at rear. Install tw o mounting nuts on terminal studs,position lead wires on studs (fig. 85), and install terminal nuts. R einstall panel in vehicle.

Wires have circuit numbers marked at ends to aid correct assembly.

91. Engine Tempera ture Gages

R E M O VA L .Remove instrument panel from vehicle (par. 89).Remove tw o terminal nuts and take off two gage lead wires. Removetw o mounting nuts, one of which is located on the terminal stud atthe side of the gage. Pull mounting clamp back off studs and removegage from front of panel. This procedure applies for either gage.

J. I N S TA L L AT I O N .Position temperature gage in opening in panel,

and place mounting clamp over studs at rear. Install tw o mountingnuts on studs and tighten snugly. Connect lead wires according tocircuit numbers and markings on gage unit. Install terminal nuts.Reinstall panel in vehicle. This procedure applies for either gage.

92. Speedometer an d Tachometers

R E M O VA L .Remove instrument panel from vehicle (par. 89) .Remove tw o mounting nuts and washers (fig. 85), and remove mounting bracket from rear of instrument. Remove instrument from frontof panel. This procedure applies to speedometer and bothtachometers.

- U P P E R MOUNTING B R A C K E T S

A C C E S S P L U G SFORPA N E LLIGHTS

C I R C U I TB R E A K E R N_ pANEL R E A R C Q V E R

ATTACHING S C R E W S -TTACHINGS C R E W S

S W I T C H GUARD-ATTACHING S C R E W S

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I N S TA L L AT I O N .Position instrument in proper opening in front ofpanel. Place mounting bracket on rear of instrument with holes forscrews and mounting studs properly lined up. Install tw o mountingscrews and washers. Eeinstall panel in vehicle.

93. LampsK E M O VA L .The lamps for the warning signals and for panel

illumination can be replaced readily without disturbing the panelitself. First use a screwdriver to pry the access plug for the panellamps, or the ruby lens for the warning signals (fig. 8 3 ) from thepanel. Then depress the lamp slightly, turn counterclockwise torelease bayonet-type catch, and remove lamp.

J. INSTALLATION.The lamps used for panel lighting and for warn

ing signals are 24-volt, 3-candlepower. Line up ribs on lamp withslots in socket, depress lamp and turn clockwise until locked securely.Install access plug or ruby lens by snapping into place.

Section XXIII. MISCELLANEOUSELECTRICAL EQUIPMENT

94. DescriptionGENERAL.This section includes description and replacement in

structions covering all electrical equipment not covered in previoussections. Testing procedures for locating faults in these pieces ofequipment are given in paragraph 4 7.

& . ELECTRICALWIRING. Electrical wiring is carried in shielded conduits or cables. Several wires are grouped together and run througha metal sheath with index plugs at each end to form a conduit. Thisshielding serves to protect the wires from dirt, grease, and other elements which might cause defective wiring. Each circuit is numberedand the circuit numbers are marked on the ends of all wires. These

numbers are indicated in the wiring diagrams, figures 3 7 and 47.SIGNALU N I T S . The signal sending units consist of an engine

temperature gage unit and a heat signal switch mounted at the upperfront of the left cylinder head, an engine oil pressure warning signalswitch mounted at the rear of the engine block, and a transmission oilpressure warning signal switch mounted at the left rear on the transmission case (fig. 108). The temperature gage unit is essentially anelectrical resistor which changes its resistance with changes in temperature. These changes are indicated by the gage

onthe instrument panel

which simply measures the resistance in the gage circuit. The heatsignal switch is a gas expansion-type switch in which the gas expandsas the temperature increases until at 2 3 8 ° to 24 2 ° F. a set of contactpoints close, forming a completed circuit. The oil-pressure signalswitches are simply low-pressure switches. With little or no pressurethese switch contacts are closed, permitting the warning signals to

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light. The engine oil pressure switch breaks the circuit at a pressure of8 to 10 pounds. The transmission unit breaks the circuit at 62 to68 pounds. At all pressures above these, the warning lights are out.

SIREN. The warning siren is mounted on the front deck next tothe left headlight. It is operated by a spring-loaded momentary con

tact switch on the full floor in front of the driver.IGNITION'SWITCHES.The two ignition switches, one for each en

gine, are located in the lower-right corner of the instrument panel(6g- 8 3 ) and are protected from accidental operation or damage by asheet metal guard. The switches have two positions: OFF with theswitch levers vertical and ON with the levers turned 90° clockwise.

/. EMERGENCYSWITCH. An emergency ignition switch, which controls the feed to the two regulator switches, is mounted in a control

box together with the circuit breaker for the dome lights on the hullroof behind and to the right of the driver (fig. 12). This switch mustalways be kept in the ON position, except in an emergency.

STARTINGSWITCHES.Two starting switches of the push-buttontype are provided, one for each engine. These switch buttons arelocated at the lower right of the instrument panel, just above theignition switches.

LIGHTINGSWITCHES.There are two lighting switches on the instrument panel: one at the upper left for the panel lights, and oneat the upper right for the main lighting system. Operation of theseswitches is covered in paragraph 47. Dome lights in the hull andturret of the vehicle are not controlled by these switches, but by individual switches integral with the lights.

PA N E LC A S E -T , P L U G — i S P E E D O M E T E RC A B L E~ rTACHOMETER C A B L E S

R I G H T MAIN CONDUIT - S I R E N / ^ E M E R G E N C YIGNITION S W I T C HCONDUIT - J BOX CONDUIT RAPD 331333

Figure 84- Cables and conduits at rear of instrument panel.

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F U E L SWITCH. The fuel switch levers, one each for the righ t andleft fuel tanks, are mo unt ed on the hull roo f in front and to the rig htof th e driv er (fig. 7). Theseswitch levers not only contr ol the circuitsto the electric fuel pumps but also open and close the fuel shut-off valves by means of a cable runn ing back to the valve at each tan k.

A P PA R AT U SBox. A n appara tus box (fig. 86) is mounte d on th efront of the bul kh ead at the extreme r ight of the driv ing compartmen t.It contains th e two generator regula tor assemblies, the two st arte r relays, and the ammet er shunt.

V E NT ILAT O R . The venti lator is located in the hull ro of betweenth e driver's and au xili ary driver's doors (fig. 12). The un it is self-contain ed , and operat es by means of a reversible el ectric mo tor which can either draw air in or blow it out o f the vehicle.

95. Condui ts , Cables , a n d Junc t ion Boxes

R EM O VA L .All elec trical conduits ar e removed in ess entially thesame manner. Unsc rew the connectors at each end and detach connector plugs. Remove the re taining clips, afte r taking out an y stowageitems or sheet me tal p arts that in terfere, and remove condui t from vehicle .

J. IN S TA L L AT IO N . Position con duit in h ull or tu r ret and install re

taining cl ips. A sse mble co nnecto rs snugly into p lace. Observe th efollowing p recautions :

(1) Make sure cond uits a re c on nected to prop e r re ceptacles. R eferto p ertinent w iring diagrams (f igs. 37 throug h 4 7).

(2 ) When insta lling connecto r plug s, make sure that th e letters onthe plug and receptacle coincide and that the to ngue and groove lineup. Do not force plugs. If plug is p roperly lin ed up, it will slip intorece ptacle witho ut fo rcin g.

(3) Do not twis t or kink conduit . See that all re taining clips are tig h tened in proper position.

96 . Appara tu s B ox

R E M O VA L . Disconnect the three conduits (fig. 86) at the top andup per side of the apparatus box. Remove the term in al cover anddisconnect the five wires (fig. 86) at the amm eter sh unt terminal block.Remove the tw o mo u nting screws an d washers at th e lower flange and

the thre e screws and washers a t the upper flange, an d remove theappar atus box from the bulkhead.IN STA L L AT I ON . P os ition the a pparat us box on the bul khead, and

install th e three upper an d two lower mo u nting screws and washers.Connect the five wires (fig. 86) to the termi nal block accordi ng to thecircuit nu mbers and instal l the termi nal cover. Connect th e threeconduits to the correct plugs in the apparatu s box.

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vMAIN LIGHTINGSWITCH

RIGHTMAIN

TERMINALBLOCKS -

•SPEEDOMETER

PANELTEMPERATUR E LIGHT

/-GA GE ./—SWITCH

-TO EMERGENCY \ AMMETER^-TO SIREN IG NITION V TACHOMETERS_ , TO FRONTEND-

-TO C OMPASS LIGHT BOX

97. Sign al Sending Units

R E MO VA LO FE N G I N ET E M PE R A T U R EG AG EU N IT. Make certain bytest (p ar. 47) that engine gage unit is at fault. Open engine compartment door. Disconnect wire togage unit. R emove water drain plugat bottom of tra nsmis sion and drain coolant below level of cylinderheads. Removegage unit from cylinder head.

I N S T A L L AT I O Nor E N G I NE T EM P E R A T U R E G A G EU NIT. Install gageunit in opening in upper f ront corner of left cylinder head.

Gage unit is cadmium-plated to distinguish it from warning signal unit,which is brass.

Do not use gasket paste or sealer on threads of unit, but tighten sufficiently to secure a good seal. Connect gag e wire according towiring diagram (fig. 45). Refil l cooling system and close enginecomp art ment door.

R E M O VA LO F E N G IN E H E ATSIGNALU N I T. Make ce rta in, by test(par. 47) that the signa l unit is at fault. Open engine co mpartm entdoor. Disconnect wire to signal unit . Removewater drain plug atbottom of transmi ssion and drain coolantbelow levelof cylinder heads.Removesignal unit from cyli nde r head.

I N S T ALL AT I O NO FE N G I N EHEATSIGNALU NIT. Install signal unitin open ing in upper front corner of left cylinder head.

Warning signal u nit is brass to distingu ish it from temp erature gageuni t, which is cadmium-plated .

Do not use gasket paste or sealeron thread s of unit, but tighten sufficient ly to secure a good seal. Connect signal wire accordin g to wiringdiagram (fig. 44). Refill coolingsystem and close engine compartment door.

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R EM O VA L O F E N G I NE O IL PRESSURE WA R N I N GSIGNAL SWITCH.M ake ce rtain, by test (par. 47), tha t switch is at fau lt. Open engine comp artmen t cover. Reachin g do wn from top of ve hicle, disco nnec twir e to switc h and the n remo ve switc h from L connection at re ar ofen gine V .

/ . INSTALLA TIO NO FE N G I N EO ILPRESSUREWARNINGSIGNALSWITCH.Re aching do wn fro m top of vehicle, ins tall switch on L connection,turnin g down fir st by hand , a nd then tighteni n g with w rench onlyeno ugh to secu re a good seal. C onnect lead wire to term inal on sw itch.Close engine c ompartment door.

R E M O VA LO F TRANSMISSION OIL PRESSURE WARNING SIGNALSWITCH. Make c e rtain, by test (p ar. 47), that sw itch is at fault.Remov e cover pla te from floor of hull un de rneath engine . Reach ingup through opening, remove dirt from around switc h, disconne ct leadwir e, and un scre w switch.

INSTALLATION O F T RANSMISSIO N OIL PRESSURE WARNINGSIGNALSWITCH . Reaching u p through openin g in hull, install switch, turningdow n first by h and, and then tig htening with wre nch only enough tosec ure a good seal. Connect lead wir e to te rminal on switch. Reinstal l cove r plate in hu ll floor.

98. Siren an d Siren S wi tch

RE MO VA LO F SIREN SW ITCH . Open m aster battery sw itch. Remove two scr ews and lock wa shers holding sir en swit ch brack e ts to

COVER BULKHEAD UPPER MOUNTIN G SCREWS AIR CLEANER

TERMINAL COV ERREMOV ED

APPARATUS BOX TERMINA L COVER RA PD 331 81 0

Figure 80. App aratus Itox and con n ections.

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hull floor. Tu rn switch a nd bracket assembly o ver, and remove twonuts holding switch conduits to te rmin als. Loosen siren conduit clip mounting stud nut and slide bot h conduits out of clip. Remove t woscrews holdin g swi tch to brack et and remove sw itch.

Z > .INSTALLATIONO F SIRENSW IT C H . Pos ition siren switch on bracket

assembly and install two mounting screws. Con nect both siren cablesto term inals on switch and tighten ter minal nuts.

C ables may be installed on either terminal.

Slip both conduits und e r clip on bracket and tighten clip screw.Position entire assembly on hull floor, and install tw o mounting screwsand lock washer s.

REMOVAL O F SIREN. Remove siren switch from br acket assemblyabove) and remov e cable to s iren by removing termin al nut. Loosen

screw holding s iren conduit clip to hull , and sl ip conduit out of clip.Remove nut from lower end of siren mounting tube, and pull siren andconduit out of ope ning in front hull plate.

INSTALLATIONO F SIREN. If rubber seal a t siren opening is damaged or torn, repl ace it. Slip conduit through ope ning and lowersiren into position. S lide m ounti ng nut o ver conduit and tighten onlower end of mounting tube. Position co n duit under clip and tightenclip. Reconnect conduit to switch and reinstall switch.

99. Igni t ion S w i t c h es

R E MOV A L O F IGNITIONSWITC H: Tu rn mas ter battery switchO FF. Remove instrum ent panel (par. 89). Take out three m ounting screws for right-ha nd conduit box at back of instrument panel(fig. 85 ), and pull box out far enough to p ermit access to rear of ign ition switches. Disconnect wires a t switch that is to be removed.Turning to face of panel, remove two screws holding guard to panel

(fig. 83). Unscrew gnur led nut aro und switch lever and remove n ut.Push sw itch and lever back and out of panel .

6. INSTALLATION O F IGNITION S W I T C H . Inser t sw itch in ope ningfrom rear of pane l, and position w ith switch lever p oi nting up. Install knurled nut over sw itch lever and turn down snugly a gainst faceof panel. Install switch guard, tightening mounting screws securely.Turn panel over, and connec t w ires to switch in accordance with wiringdiagr am and markings (fig. 38). Posit ion conduit box on mountingstuds and install three attaching screws. Inst all instrument panel invehicle.

R E M OV A LO F EM ERGENCYIGNITIONS W I T C H . Turn m aster batt eryswitch OFF. Remove four cap screw s an d lock washe rs that holdemergenc y ignition switch box cover in pla ce and' remove cover anddome light from box as an assembly. Disconnect wires to switch, andre mo ve sw itch afte r taking out hex nut at front.

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INSTALLATION O F EMERGENCY IG NITIO N SWITCH. In st all switchthrough ope ning in switch bo x and attach A vith hex nut. Con nectwires to swit ch in accord ance w ith wiring diagra m and markings (fig.38). P ositi on cover and dome light asse m bly again st switch box andinsta ll four cap screws and lock w as hers.

10 0. Star t ing Switches

K E MO VA L. T urn ma ster battery switc h OFF. Bemov e instrume nt panel from vehicle (par. 89). Take out three m oun ting screw sfor right-hand conduit box at re ar of instrum ent panel (fig. 85 ), a ndpu ll box out fa r en ough to permit access to starting switches. Disco nnect wires at re a r of switch to be removed. Tu rn ing to face ofpanel, remov e ru bber dust seal, loosen the large hex nut surround ing

switch b u tton, and remov e nut. Pus h swi tch back an d rem ove fromrear of p ane l.

i . INSTALLATIO N . Insert switch in opening from rea r of panel , andinstall large he x nut and rub ber dust seal at fr ont , turn ing down un tilsnug aga inst face of pane l. Turning to ba ck of pan el, conn ect wiresto swit ch terminal s accord ing to wiri ng diagr am and mark ings (fig.3 7) . Position condu it box on mount ing studs a nd in s tall three attaching screws. Install inst rum ent panel in vehic le.

101. Ligh t in g Sw itches

REMOVAL. Both the pan el li ght switch and the main light swit chare removed by the same procedure. Turn master b attery switchOFF . Remove instrument pane l (par. 89). Dis connect wires fro mter minals at rear o f swit ch. Remove hex nut from sw itch leve r shaft,rem ove switch plate, and take switch out from rear o f pa nel. Takescrew out of ce nter of switch le ve r (fig. 83) and re m ove lever from f aceof pane l.

INSTALLATION. Insert switch in openi ng from re ar of panel,po sition switch plat e aga inst face of pane l, and install reta ining nuton switch lev er sha ft. Pl ace switch lever on sh aft and secure in position with round-h ead screw. Test leve r for pro per operation . Conne ct wires to switch terminal s, in accordan ce w ith the wiring di agram(fig. 40). Insta ll instrum ent pan el in vehicle (par . 89).

102. Fuel Sw itches

R E MO VA L . T urn m aster battery swi tc h OFF. Disco n nect bothfuel va lve ro ds at switch le v ers. Disconnec t el ectrical condu it ate mergency ignitio n switch box. R emove four cap screws and lockwashe rs, and remove switc h assembly fr om hull roof. R emove individual swi tches or circuit br eaker by disconne cting wires and re movingattach ing screws.

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6. INSTALLATION . Install in di vidual switc h or circui t bre aker, a ndconnec t wires as indicated in diagram (fig . 46). Po si tion swit ch assem bly agains t h ull roof with m oun ting hole s corr ectly al ine d, andinsta ll four cap sc rews and lock w ashers. Co nnect conduit to receptacle a t re ar o f em ergency ign ition switch box. Con n ect fuel sh ut-off

rods to sw itch lev ers. Check opera tion of fuel val ves, and re adjust ro d s if nece ssa ry.

10 3. Ven tila tor

R EM O VA L . T urn ma ster battery sw itch OF F. Discon ne ct conduit a t elbow on le ft si de o f v entilato r. Remove fou r cap screws a ndlock w ashe rs arou nd u pper m ount ing fl ange , an d remove ven tilat orfrom vehic le as an ass em bly.

&. IN STA L L ATION . Posi tio n ventila tor ass embl y on m ount ing flangein hu ll roof, install four cap screws and lock washer s, an d tig htensec urel y. Connec t conduit from emer g ency igniti o n switch box toelbow on s ide of venti la tor.

Sec tio n XXIV . RADIO IN TERFERENCE SUPPRESSION

1 04. Pur p o s eTh e purpose o f radi o inte rf erence su ppress ion is to elimina te or minimize electrical dis turbance s w ithin vehicle whi ch would int e rfere withradio reception, o r would disclose the lo cation of ve hic le to sen sitiveelectrical d etec tors. Th erefore, i t is impo rta nt that vehicles with, aswell as veh icle s withou t, rad ios be su ppressed properly to preve nt inte rfer enc e w ith ra dio rec epti on of neighb orin g vehicles.

105 . Desc r ipt ion

Suppres s ion is accom plished by use of capa citor s (con den sers), bo n ding jump ers (gro un d straps), and by toot h ed lock wa shers. Wir ing,wh ich m ay carry in terfering e le ctrical sur ges to a po int where in terference w ill affect rad io rece ption , is sh ielded. Th e tooth ed lockwas hers and groun d s traps loc ate d throug hou t the veh icle tend to bindthe ent ire unit toge ther into a solid shield .

1 06. S u p pre s s ion Co mponen t sLoca ti on of suppre ssion comp o nents is giv en below.

IGNITIO N S Y S T E M. (1) The hig h-tensio n leads from distribu to rsto spark p lugs are inc losed in loo se- braid m etal sh ielding whic h term inate at the ferru le s provided at each d istributor an d spark pl ug (fig.89).

752022 O— 47—_12 17 3

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(2) Th e high-tension lead from each distr ibutor to eachignition coilis enclosed in loose-braid metal shielding and terminated at ferrulesprovide d at each distribut or and coil.

(3 ) The low-tension lead from each distributo r to each ignition coilis enclosed inloose-braid shielding and terminated at ferrule provide d

on each d istrib utor and ignition coil.(4 ) The low-tension lead, from each ignition coil to each ig nit ionswitch, is enclosed in flexible metal-tube sh ielding, te rminating 10inches from each coil but ground ed to each engine block through apressure clip and at the instrum ent panel by meansof fittings.

(5 ) Th e tw o ignition coils are integrally shielded and incorpo rateferrules at ele ct rical connections for terminati ng shielding of external wiring wi th the exception of primary lead from coil , where theshielding terminates appro x imately 10 inches from the coil. O necapa citor is built into each coil and is connected to battery terminalof each coil. E ach coil is mounted on a bracket which bolts to enginehead. B oth coils and b rackets are groun ded by means of toothed lockwashers.

(6) Each distr ibutor cap and base is integrally shielded an d inco rporates ferr ules at electrical connections for terminating loose-braid shieldi ng o f external wirin g. O ne resistor su ppresso r moldedin each to wer of bo th distributor caps, eachcap having nine towers.

(7) The 16 sp ark plugs are integrally shielde d w ith suitable ferrulesa t electrical connections for ter m inating shi elding of high-tension leads. O ne resistor suppres sor is internally mounted in each integrally shielded spark p lug.

E N G I N EB O N D I N G .Ea ch engine is bonded to hull by a gro undstrap fr om each engine support po.st (fig. 88) to hull floor. Eachengine mo unting stand is grounded to transf er case by a grou nd strap(fig. 65) . Each air intake tube is grounded to hul l crossmemberby agr ound st rap (fig. 89).

C H A RG I N GSYSTEM. (1) The tw o regulators are enclosed in anapparatu s box which fastens to hull by means of plated bolts andcleaned surface s under heads of bolts (fig. 86). T he gener ator terminals are completely covered by a shield which fastens to generator bym eans of a spr ing clamp. The armature and field leads between regulator and generator (fig. 88) are jointly enclosed in metal hose shield ing, terminated in a fitting at the gener ator and at shielded termin alsat the appa ratus box which honses the tw o regulator s (fig. 90) .

(2 ) Two 0.1-Microfared concentric capacitors ar e mounted in th ehousing of each gene rator an d are connected to positive brush terminalsof each generator .

(3) O ne 0.1-Microfarad feed-through cap acitor is mounted in eachregulator sub-base and connected in lead to armatu re term inal of eachregulator. O ne 0.1-M icrofarad feed-through capac itor i.s mounted in

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TOOTHEDLOCK

WASHERS

CAPACITOR

87.

each regulator sub-base an d connected in lead to ba ttery termina l ofeach regulator. One 0.001 9- Microfarad capacitor is mounted in eachregulator sub-base and connecte d in series wi th a 4-ohm resistor to thefield terminal of each re gulator. Each regulator is groun ded to regulator mo unting bracket by ground straps from two of the regu latormounting feet to the moun ting bracket (fig. 90). Both regula torsare m ounted on the brack et and this bracket is welde d to the base of theapparatus box.

HOWITZER ELEVATING MECHANISM. (1) T wo 0.1-Microfar adcapacitors are moun ted on howitzer elevating motor ho us ing, and areconnected, one each, to the motor control supply terminals ( forwardand rev erse). The h owitzer ele vating motor is groun d ed to gun m ountby plated b olts and was hers.

(2 ) Two 0.1-Mi crofarad capacitors are mounted inside the gun switch box and co nnected, one each, to th e motor control supply ter minals (forward and revers e). O ne 0.1 Microfarad capacitor is mounted

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inside the h owitze r switch box and connectedto the batt ery terminals.The howi tzer switch box is grounded to hull with int ernal-externalplated too thed lock washers under heads of bolts. A fter vehicle ser ialN o. 70 all w iring leads associated with the howitzer e levating mechanism are enclosed in flexible m etal shielding.

V ENTILATINGFA N M O T O K . O ne 0.5-Microfa rad capacitor ismounted in the ventilating fan mo tor case and connected to switchof motor.

/. R A D I OTERMINAL B O X E S . T wo 0.1-Microf arad capacitors aremounted in each of the ra dio terminal boxes and connected, one each,to the 12- and 24-volt terminals (fig. 87).

B O N D I N GB Y G R O U ND S T R A P S .Ground straps are used at following points

(1) Engine suppor t post to hull floor (fig.88).(2 ) Engine moun ting stand to transfer case (fig. 65) .(3 ) A ir-intake tube to hull crossmember (fig. 89).(4) Distributor to hull crossmember (fig. 89) .

(5) G enerator to generat or bracket (fig. 88).(6 ) Regula to r mounting feet to mounting pla te (fig. 90).

GROUND STR AP — GENERATOR TO MOUNTING BRACKE T

GROUND STRAP—ENGINE SUPPORT TO HULL FLOORLOOSE BRAID SHIELDING—ARMATURE AND FIELD LEADS

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A. BO ND ING B Y TOO THED L O C KWASHE RS. T he attach in g scr ews o fall c lips or clam ps w h ich sup po rt co nduits and p ipes and w here c lipsare an chored to tapping blocks are p ro vided with toothe d loc k washers. Too thed lock w ashers are used also to bound mech anica l part s atthe followin g point s:

(1) H owitzer sw itch box to hull.(2 ) H owitzer sw itch box co ver to box.(3 ) Howitze r li mit switc h box cover to box.(4) P eriscope to hatch door .(5 ) M aster s w itch box to hull.(6 ) Regul a tor appara tus box to h ull.(7) A ir ventil ator assem b ly to hull.(8) Fuel p ump moun ting p late to fuel tank.

(9) Fu el pu mp te rm inal casti n g to mou n ting plate.(1 0) Fend e rs to hull.(11) B ulk head ext ension a ngl e to transfe r case shie ld .(12) Attac h ing screws fo r all elec trical nuts.

107. Ma intenanc eIGNITIONSYSTEM . The f ol lowing po ints of atta c hment mu st be

ke pt se curely tig htened:(1) Distr ibutor bond s trap at di s tributor end and at hul l cro ssmem-

ber.(2) All di st ributor hi gh- tension leads at dis tr ibutor tow er end and

co upli ng nut a t spar k plu g end.(3) Sp ark p lug ex tensio n (sup pres sor) n ut on spark plug.(4) Screws attachin g to p half of suppo rt bra cket for hi gh- tension

leads.(5) Nu ts attachi ng ig nition co il-to-coil mo untin g b rac ket.

C H A RGIN G SY ST EM . Capac itors in engi n e genera to r h ousing andin regula tors are internal ly mo unted and, in case of failure of ca pacitors, the g ene rator or regul ator sh o uld be rep laced .

HO WITZERE L E VATING M O T OR A N DSWITC H Box. T h e capacit orsat tached to th e ho witzer motor lead s and to th e howitzer swi tch boxlea ds can be repla ced by disc onnec ting th e above le ads and rep lacingde fective capa citor.

RADIOTE R M I N A L BO X E S . Rem ov e term in al box cov er and remove capacit ors w hich are connecte d to pos itive terminals a nd an

chore d by box at taching screws. W hen new capac ito rs are in stalled ,make sur e that su rf aces are cl ean, and th a t to othed lock w ash ersar e use d on attaching screws. Co nn ect capac itors to te rminals assh own in figur e 87.

WIRIN G SY ST E M . Con duit su ppor t clip attac hing screw s mus tbe k ept tigh t and secure d by the pr oper type lock washe rs . Con duit couplin g nuts must be kept pro p erly tight en ed.

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Section XXV. FUEL AND AIR INTAKE A ND EXHAUSTSYSTEMS

108. Fuel System Description an d Data

DESCRIPTION. (1 ) The fuel system is illustrated in figure 91 .

T wo fuel tanks, of approximately 55-galloncapacity each, are carriedin narrow, deep compartments on each side of the engine compartment.

(2 ) T wostrainers are incorporated in the fuel pump support assembly in the fuel tanks. The first is a cylindrical strainer extending fromthe top of the fuel tank filler opening to the top of the fuel pumpmounting cage (fig. 98) . This strains the fuel as it is poured into thetank and also acts as a flame arrester. The second strainer surroundsthe fuel pump mounting cage at the bottom of the tank. This strainsthe fuel in the tank as it passes to the pump, and is self-cleaning due tosloshing action of the fuel.

(3) Each carburetor is equipped with a small disk-type auxiliaryfuel filter, which is mounted in a horizontal position on the carburetorfloat chamber fuel inlet fitting. This filter will retain the small particles of dirt which may pass through the main filter at the bottom ofthe fuel tank. The filter has a movable bowl to provide a means ofcleaning.

GROUND STRAP—DISTRIBUTOR-TO-HULL CROSSMEMBERGROUND STRAP—AIR INTAKE-TO-HULL CROSSMEMBER

LOOSE B R A I DSHIELDING M E TA L -C L A D D I S T R IB U T O RCA P

178

FERRULE

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AP PARATUS B OX (COVE R R E M OVED) G E NERATOR REGULATORS

GRO UND STRAP-REGU LATOR F E ET TO MOUNTIN G PLATE RA PD 33 1963

Fig ure 9 0 . Ap pa ratus box—re gulato r groun d straps.

(4) A fuel line extends fr om each fu el pump th rough th e top ofthe fu el pump supp ort assembly , fo rward to a check valve, and thento the shut-off valve. From these shut-off valves, a con nectin g line iscarried across the sup port a t the front of the engi ne compartmen t.T his line co ntains tw o T-connections, from which a rubb er lin e extends to the auxil iar y fuel filter a t the carburetor float chambe r (fig.91). This makes it possible for eithe r tank to supply fuel to bothengines.

(5 ) Th e flow of fue l and selection of th e tank is con trolled by a pa ir of levers and switches at the fro nt cente r of the driving co mpartmen t roof (fig. 7). From each of these levers, a control cable ex

tends back to the sh ut-off valve and the feed wire for the pump exte ndsback to the terminal on to p of the fuel pump sup port assembly, fro m w hich it is carried in an insulated c ond uit to th e pu mp.

6. D ATA . (1 )M a k e—— — — ——— — — — —_— _. Ca rter.Type_ __ _____ __ _____ __ . WCD duel downdra ft.Gas line c on nection s. ______ _ %-inch hose nipple.Id le adjus tm ent____ _ ______ Screw ty pe.Fla nge s ize__ ___ ___ _ __ __ 11,4-inch.Choke ty pe ——— _— _____ _ Autom a tic clima tic control.

(2 )Mak e— —___ _ _______ _ __. Carte r.L oc ation... — ______ __ ____. In cage a t bott om of fu el tank.Type _ ___ __ _____ __ __. Cent rif ugal, ele ctr ically d ri ven.

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Number______________ 2,1 in each tank.Control_______________. Switch and manual shut-off valve.Pressure___—__—__——_—. 6 pound.Octane rating of fuel___—___. 80.

(3 )Location______________. Filler support, pump cage.Make_________________ Eipley.Type_______________. Self-cleaning screens.Number.__—________— 4.

(4)

Location______________. Carburetor float chamber.Make_________________. Zenith.Type_________________ Disk-type.Number_______________ One eachcarburetor.

(5)

Number_______________. 2.Type_________________. Oil bath.Make_________________ A . C. or Donaldson.Filter elements____________ Steel mesh or Tampico fibre.

Reservoir capacity_________ 3 quart.Location_______________ Front of bulkhead.

109. Air Cleaners

D E S C R I P T I O N .T wo large-capacityair cleaners are provided, onefor each carburetor,mountedon the bulkheadat the rear of the drivingcompartment. Thesecleaners areof the oil-bath type. Air from the

inlet grille above the radiators passes over the oil and through th efiltering element and is carried through tubes in the engine compartments to the carburetors.

S E RV I C I N G .Loosen the two wing nuts holding the air-cleanerreservoir to the air cleaner. W hile supporting the reservoir frombottom, swing outthe clamp bolts and lower the reservoir. Removescreen from Donaldsonair cleanerby turning screen counterclockwise,then pulling screen down out of air cleaner (fig. 92). Removeelementfrom A . C. cleaners by pulling same downward. Pour out old oiland clean reservoir and screen with dry-cleaning solvent. Dry allunits thoroughly with compressed air, if available; fill reservoir tolevel indicated, using approximately 3 quarts of engine oil (seasonalgrade) and reinstall screen and reservoir.

R E M O VA L .T he air cleaners aremounted to a bracketon the driving compartmentside of the bulkhead by means of two metal straps

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FL

C

C

C

V

V

FU

P

MP

S

O

A

MBY

FU

SH

O

V

VT

C

N

ON

i

»——-

I

^h

O

L—FU

LN

A

MBY

RGH

FU

T

NK

F

O

O

V

HC

\

FU

SH

OF

V

V

LF

N

H R

3

CO

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that encircle the unit (fig. 92) . Working in dri ving compartment,loosen hose clamp holding air cleaner in let pipe to air cleaner. Ke-move scre w holding each strap arou nd ai r cleaner and li ft completeassembly from its mou n ting.

I N S T A L L AT I O N .(1 ) The a ir cleaners are

interchangeable as rights an d left s by interchanging the plate retainedby eigh t screws with the inlet p ipe on the cleaner. The outlet openingon the air cleaner is n ot removable , but is part of the c leaner itself.The outlet opening must always be connected tothe ca rbu retor inletpipe.

Caut ion: If the air cleaner is installed i ncorrectly, oil will be drawnout o f th e air cleaner and into engine.

(2 ) Coat the in sid e of the carbur etor air intakehose connection with joint and thread compound (cement,type II)and slide outlet on a ir cleaner into hose. Ti ghten hose clamp securely.Position two metal straps aroun d air cleaner and tighten screwssecurely.

1 10. C a r b ur e t o r s

DESCRIPTION. The carburetors are C arter W CD type, of dueldown-dr aft design, int ernally vented and fitted with d u stproofingseals. Each of the duel barrels in the carburetor supply the fue l mixture to fou r cylinders through the intake manifolds. Each carb ur etor

R IGH T CARBURETOR AIR CLEANER

CLAMPING STRAPS

LEFT CARBURETOR AIRCLEANER

RESERVOIRCLAMP BOLTS

A IR C L E A N E RSCREEN A I R " C l E AN E RRESERVOIR— '

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is fitted with an auxiliary fuel filter whic h is located at the fl oat chamb er inlet.

C A R B U R E T O RADJUS T M E N T S . T est choke shaf t w ith fingers atmanual control to see that choke op erates freely (fig. 94). Eu n eng ines until thoroughly w arm; then adjust thro ttle stop screws (fig. 93 )

so engine speed is from 450 to 475 revolutions per minute, with thetransmission selector lev er in "DRIVE" position and pa rki ng brakesset. Tighten two id ling mix ture ad justing screws (fig. 93 ) as far aspo ssible with out forcing; then loosen screws 1*4 turns. Engines shoul drun smo othly wit hout lop ing or stalling . Readjust screws if necessary. Check to see th at choke setting mark on choke ther mostat hou sing is opposite mark on carbu ret or flange. If necessary, loosen threeth ermostat housing screws and rotat e hous ing until mark s line up (fig.93). T ighten the screws.

REM O VA L . Disconn ect choke thermosta t air line a t carburetorand at manifold and remove line. Disconnect distributor vent ilatinglin e at carburetor air intake elbow. Loosen hose clamp at carbureto ra ir inta ke elbow (fig. 6 2) and lift elbow off carburetor. Make su reboth fuel tank control levers (in driver 's comp artment) are in "OFF"

THERMOSTAT HO USINMOUN TING SCREWS

CHOKE THERMOSTATHOUSINC

IDLE ADJ USTING SCREWS-^ THROTTLE STOP SCREV THROTTLE ROD

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AIR INTAKE E LBOW CRANKCASEAIR CLEANER

CARBURETOR C H O KE S H A F T — CAR BURE TOR RA PD 331818

CARBURETOR

C R A NK C A S EVENTILATOR AIR

CLEANE R

GASKETS

INSULATORINTAKE

MANIFOLD

THROTTLER O D ]

18 4

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positions. Loosen hose clam p at carburetor auxiliary fuel filt er andslide hose off connection. Loosen hose clamp at crankcas e bre athertube at rear of carbur etor and slide hose off nipple. U nhook throttlepull-back spring from thrott le rod and slide rod out of throttl e shaft.Remove four nuts hol ding carb uretor to intak e manifold and remove

carburetor and upper gasket (fig. 95). Leave insulator and lowergasket on mani fold .

INSTALLATION.Ins tall a new gasket over in sulator on intakemanifold. Place carburetor over mounti ng studs on intake manifoldan d install four retaining n uts. Slide rubber gasoline hose o ver connection on carb uretor a uxiliary filter and tighten hose cl amp. Connect cran kca se breather hose to fitting at re ar o f carburetor and tighte nhose clamp. Connect choke the rmostate air line to carbure tor and to

exhaust ma nifold by screwing nut on pipe in to fitting on carbu retorand manifold. Tighten secur ely . Slide air intake elbow over top ofcarbu retor an d tigh ten hose clamps securely. Connect air lines tocarburetor intake elbow and t ighten securely. Slide trunnion onthrottle rod thro ugh throttle shaft lever, hook p ull-back spring toh ole in trunnion, and connect sp ring to bracket on manifold fron tclam p b olt.

T HR OT T L EL IN K A G EA D J U S T M E N T.(1) Run engines until theyar e thoroughly wa rm (at least 165° F.) so that choke valves are wide open. Adjust th rot tle stop screw so tha t each en gine speed is from 450 to 475 revolutions per minute as no ted on the tachomet er, with thetransmission selector le ver in DRIVE posit ion and parkin g brakes set.Insert a - inch d rill rod through cross shaft relay lever and crosssha ft mo unting bracket on left engine to set throttles in zero pos ition(fig. 96). If pin does not line up with holes in lever and mountingbracke t, turn throttle adjusting nut on end of throttle rod assemblyuntil pin slid es thr ough both holes freely. Rem ove the pin. Pull outhand th rottle until engines a re turning over approxim atel y 1,000 revolutio ns pe r m inute. Sp eed of engines shoul d not vary more than 50revolutions per minute at idling speed, or 100 revolutions per minute a t 1,000 revolutio ns per mi nute. Equalize speed o f engines by turning throttle rod assembl y adjusting n ut a t end of throttle rod. Withengines turned off, pull up on engine cross shaft to rea r relay rod asfar as possible to set throttle in wide-open positi on, and be sure thatthrottle valves are wide open.

(2 ) Working in driving com partmen t, push down on acceleratorpedal (with engines not running) until throttles are in wide-open position, and measure d istance bet wee n accelerator pedal and front hullplat e. This distan ce should be one-e ig hth inch wi th throttle linkagein full-open position. If clearance is inco rrect, dis conn ect rod frompedal cross shaft lever to front throttl e relay and turn clevis until

clea rance is secured. Reconnect rod and tighten lock nut.

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Engage auxiliary accelerato r and adjust pedal in same mann er. Adjust hand th rottle by turning adju sting nuts on end of hand-thrott lecable until nuts are one-eighth inch from trunnion w ith throttle linkage in closedposition. Be sure of freedo m betweentrunnion and hand-throttle-cable extension. Bend m ou nting bracket, if necessary, toline

up cable with trunn ion./. S E RV I C I N G AUXILIARYF U E LFILTER. Loosen bail nut and remove

bowl fro m filter. Do not tr y to remove gasket as it m ay be cementedin place. Wash filter element with dry-cleaning solvent.

Caution: Do not damage the disks. Do not scrape or scrub or usecompressed air. D o not disassemblethe filte r element. If elementcannot be cleaned sati sfactorily, replace entire element assembly.Wash fuel bowl before reinstall ing. Install fuel bowl on filter,

making sure that gasket is in place and tighten bail nut. Nutshould be tightened fin ger-tight. If bail nut is overt igh tened, thegasket may be cut by the fue l bowl or the bail stretched to the pointwhere a good seal between the bowl an d the filter body ca nnot be obtained. In the event the bail has been stretched, it may be kin kedslightly to allow the bail nut to contact the bowl. Check fo r leak when engines are running.

111. Fuel Pump s

DESCRIPTION. An elec tric fuel pump is mou nted at the bottomof each fuel tank in a screenedcage at the lower end of the fuel-pumpsupport assembly. Thi s pump consistsof a small electricmotor which

C ROS S SH AF TSUPPORT

GAGE P IN HOLE

THROTTLEROD

1/4-INCH P IN

R A PD 3318O7

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rotates a cen trifug al-type im peller (fig. 9 7). The entire pu mp assembly op e rates submerged in gasoline.

6. R E MO VA L . Fue l pum ps normal ly requ ire no att ention in service.To repl ace an inoperat ive pump, remov e the suppor t assemb ly byfirst tu rning maste r sw itches to the "OF F" position, and then rem ov

ing fuel-tank-cover p late by rem ovin g th e attachin g screws and lif ting off plate (fig. 9 9). R emove screw which hol ds pu mp feed wire to term inal and tape end of wire. L oosen hose cl amp at fuel-outl et

SHIELDED FEED CABLE-i FUEL OUTLET CONNECTION -

MO TOR HOUSING-

TERMINAL BRACKET ST RAINER^

pum p.

FUEL CHECK VALVE

FUEL P UMP F EED-TE RMINAL

UP PER STRAINER AND FLAME ARRESTOR —

FUEL PUMP FEED-C ONDUIT

- FUEL FILLER CAP

FUEL FILLER

-FUEL LINE

CAGE F OR FUEL PUMP

LOWER STRAINER ——\

R APD 3313 47

Figure

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elbow and slide hose off nipp le. Remove 12 att achi ng screws andremove completesuppo rt assembly (fig. 98 ). R e m o v e four screwsholding coverto bo ttom o f cage and removecover. Loosen hose clampat fuel pump discharge p ort nipple. Remove four co tter pins andmounting cushions, an d lower pump in mount ing cage. Loosen set

screw at electrical -feed cable at top of fuel pump and unscrew feed-cable connection. Removefuel pum p from cage.I N S T A L L AT I O N .C onnect electrical-feed cable to top of fuel pump

and lock in pla ce with set screw. Raise pump in mounting cage and,at the same time, insert discharge-port nipple into hose. Installmounting cushions and fo ur new cotter pins, and tighten hose clampsecurely. If cage-cover seal has been removed, install seal agains tupper cage flange. Pla ce cover on bottom of cage and install four

att aching screws.Position

a newg asket

onfuel tank and slide

sup port assemblyinto fue l tank an d into retainer in bottom of tank. Install 12 atta ching screws, m ounting ground strap under one screwand tightening all screws securely. Connect fuel line hose connec tion to nipp le and tig hten hose clamp (fig. 99). Remove tape fromend of feed wire and install on terminal. Place rubber gu ard o verterminal. P osition fuel tan k coverover open ing and install attachingscrews.

112. Fuel Ta n ks an d LinesDESCRIPTION.Two fuel tanks, of approxim ately 55 g allons each,

are carried in narrow, deep compartments on each side o f the enginecompartme n t. Each tank contains a cover and pump support assembly on which are mounted all of the parts normally requi ringservice.

& . DRAIN IN G . A drain-hole cover issecured to the hull floordirectlyunder each fuel tank (fig. 26). To d rain the tank , remove the fourcap screws holding the plate in position, and remove the drain plugat the b ottom of the tank.

RE M O VA L .Unlatch battery comp artment covers and lift ojF covers. Removecoversover fu el tank s by remov ing the attachi ng screwsand liftin g off covers. Turn master battery swi tch to position.Disconnect fuel pump feed wire at t erminal and tape wire. Disconnect terminals at battery. R e m o v etw o battery hold-dow n n uts (fig.80). Remo veho ld-dow n and lift out battery. Remove battery boxretaining screws and lift out battery box. Remove screwholdinggr ound strap to top of fuel pump support assembly. Remove screwsholding conduit clam ps to fuel tank cover angles and lay conduit toone side. Loosen hose clamp at fue l pump assembly outle t and slidehose off connection. Remove tw o screws holding shut-off valve assembly to side of hull; disconnectfuel li ne at shut-offvalve byloosening hose clamp and slide hose off connection. Lay condu it and shut-

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off valve ass embly to on e side. Kemove screw s holding comp artm entco ver angles to h ull and remove an gles. Rem ove screw s holdin g f latsp ring spacer s to insula tin g pad on inner wa ll of comp art ment an dpull ou t spring sp acers. Att ach a rope s ling throu gh lifting handleson fuel ta nk and remo ve tank fr o m compar tment.

INSTALLATIO N. L ower fuel tan k into compar tme nt. Ins tall thre efl a t spr ing sp ac ers betwe en tank an d inner com partment, sliding int ogroo ve provide d. Inst all ret aining screws. Positi on fuel tan k com p art ment angle s aro und o pen ing, m akin g sure that the seals are inpr oper p osition , a nd install an gle attachi n g screws. Ins tall b atter ybox. L owe r batt ery in b atte ry box and install h o ld-downs. Connectterm inals to b attery (fig. 80). Plac e shut -off v alv e assem bly again s tinner co mp artment wall and i nstall two at taching screws. Rec onne ct

fu el line to shut -off val ve a nd ni pple on fuel pu m p su pport assemblyan d tig hten h ose clamps. Ins tall th ree scre ws a nd clamps holding con duit to in n er fuel com pa rtment angle . Co nnect grou nd s trap to topof fu el pump s uppo rt asse mbly , an d reconnect feed wi re to termin al.In stall rubb e r gu ard ov er terminal . Pos ition fu el tan k cover and b attery cover over o pen ings and install att ac hing screws.

R EP L A C EM E N T o r L I N E S . (1) T he main fu el line exten d s fromone fu el tank to the o ther, and is carr ied ac ross the sup port at the fronto f the eng ine compar tment (

fig. 91). This line

c

onta ins two T connec tions from w hich a rub ber line ex te nds to an auxiliary f ilter at thecarb u retor float chamber s. The fu el lines are conne cted to th e T'sfor the carb u retor by sh o rt hose co nn ections. Thes e con nections ar eof a rieo pren e com position, an d should n ot be rep la ced with o rdina ryru bber hose.

(2) Wh en removi ng t he fuel line , be su re fuel cont rol levers are inthe OFF p osition. R emove fu el tank cover. Disco nn ect the fu elline at the sh ut -off v alve at the side o f the eng ine compa rt ment byloosenin g hose c lamp s and s lidi ng hose off pipe. Dis c onnect fue l hoseat each carbu retor aux ilia ry filter b y looseni ng hose clamp and sl iding hose off nipple. R emove fou r bolts and c lamps ho lding main line toth e suppo rt bar an d lif t the fue l line as an assembly o ut of vehicle.

(3) To reins tall th e fuel line , positi on the assemb ly again st thesupport bar and instal l the four b olts and c lamps hold ing m ain lineto bar. Slide fu el hose ov er nipp le at carb ure tor auxilia ry filter an dtigh ten hose cla mp . R eco nnect fu el line a t sh ut -off valve and tighten

hose clam p. Start b oth engine s and run for a sufficient length o f timeto chec k a ll con necti ons for le aks. Instal l fuel ta nk covers . Closeengine c o mpartmen t.

113. Ex h au s t Pipes and Mufflers

G E NE R A L . The exh aust system , consi sting o f the ex haust mani folds , manifo ld connec tion s, mufflers, and exh a ust p ipes can be re-

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moved w ith t he engines in th e vehicle. The removal of the exhaustman ifolds and ma nifold connection is covered in parag rap h 65.

REM O VA L .(1) Turn doorlatches and rais e doors.

(2) Refer to

para gr aph 67.(3) Remove bolt and lock washer attachi ng exhau st pipe extension to exha ust pipe outlet elbow. Removebolt at rear o f exh aust pipe extension on extension shield an d slideextension towards rea r enough to clea r ou tlet elbow (fig. 60). Remove screw an d nut attaching muffler outlet p ipe support brac ke t tomuffler in let pip e assembly. Loosen two nu ts at outlet pipe clamp atmuffler, work outle t pipe free of muffler, and remove from vehicle.Remove two bolts

and nuts holding

mufflerand inlet p ipe

assemblyto exhaust man ifol d connection pipe (fig. 61), and remove muffler.D iscard used gasket.

(4) Refer to p ar agraph 65.IN ST A L L AT I O N . (1 ) Re fer to p ara

g raph 65.(2) Lowe r muffler and in let pipe assembly into

p osition in vehicle . P lace a new gasket between the exhaust connection flange and muffler inlet assembly. Install two bolts and nutsho lding muffler inlet assembly to exhaust connection flange. Insert end of muffler and ou tlet pipe into muffler and positio n clamp aroundpipe and muffler. Install screw and nut which attac h outl et pipesupport br acket to muffler inlet pipe assembly.

Do not tighten bolts at mufflerclamp or at supp ort bracket u ntil exhaustpipe extension is tempor arily installed for alinem ent of rear support b olt.

Tight e n bolts at muffler and sup por t and remove exhaust p ipe

extension.(3) R e fer to paragrap h 686(1 8).

(4) Slid e exhaust pipe ext ensionthrough exten sion shield an d i nto muffle r outle t elbow (fig. 60) . Ins ta ll attach ing sc rew at outlet elbow. Install exh aust pipe extensi onrear support bo lt at extension shield and tighten sec ur ely (fig. 60).

(5) Refer to par ag raph 6 8 &(20).

Section XXVI. COOLING SY STEM

114 . Description an d DataDESCRIPTION. (1) T he veh icle is eq uipped with tw o identical,

but co m pletely independ ent co oling syste ms, one for each eng ine andtransm ission (fig. 100). Each system contains th e fol lo wing major

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units: rad iator, w ater p ump , thermos tat and necessary connections,engine fan and fan dr iv e, and oil cooler for th e hydrama tic tran smis sion.

(2) The coolant is dra w n from th e radiator by the wa te r pump and forc ed into the engine water jackets . After c ircul ating through bot h

cylind er blocks and cylinder heads, the heate d co o lant is for ced upth rough hose connections to the upp er tan k of the radiato r. A block ing-type bime tal th erm ostat w ith double pop pet valves, located in theradiator inle t h ousin g, p ermits free flow when the coolant is hot.However, it causes cold fluid to recircu late throug h a bypass hose backto the w ate r pu mp an d th rough the engine u nt il the engine reaches anefficient o pe rating te mperatu re.

(3) Cooling fluid is also pumped thro ugh an ex te rnal pipe to an

oil cooler locatedin t he transmis sio n oil pan , where it cools the tra ns

mission oil and is returned to the wate r pump.(4 ) The cap acity o f each cooling system is 40 quarts.(5 ) Th e engine fa n is carried in a mou n ting sp ider attached to th e

fan shr oud at rear of rad iator. The fan is driv en by a dr ive sh aftmounted on ball b earings un der the in take manifo ld, an d thr ough au niversa l joint and yoke connected to the g enerato r pulley.

Z> . T A B U L AT E DDATA. (1)

Blades, angle_ __ ______ __ ___—— — 32°.Blades, d iamet er_ _____ __ ___— _ 21 inch.Blades, num ber of _— — —____ _— _. 4.Drive .__ _____ ___ —___ __ ——— . Belts, drive shaft and u ni

vers al jo ints.Drive ra ti o_____ __ ______ _ —_—. 1.1 to 1Mak e___ ___ ____ ___ ____ _— __ Hayes.

(2)Core a rea (each) _— ——__ __ —_—_ . 540.5 squ ar e inches.Type—— — — — __.__________— — — — —— . Tube-and-fin.M a ke._— _ ___— __ _____ _— __ Harr is on.

(3)Loc ation ____ __— _—_ ___ ____ ___ R adia tor inlet housing.Ope ning temp era ture— ___ ____ ___ _ 140° to 146° F .T ype-__ __ _____ — —___ __— ___ Bime tal.Ma ke._ ____ ___ ____ ___ ____ __. Dole valve.

(4)

D rive__— ______ _ _______ _ ____. T riple belt.Lubr ic ation___ _— ——_ __ ______ — _ Fitting .Pac king s___ ____ —_ ____ ____ ___ S pring-loa d ed, chevron-

type.Type-__ _______ _______ ______ Centr ifugal .Locat ion— —— ___— _—_ .___ __—_ __. Rig ht fron t of engine

blo ck.

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c. CLEANING. (1) Open the petcocks which shut offthe coolant from the heaters or other accessories, if used, to allow forcomplete circulation during the cleaning, flushing,and draining. Runthe engine, with the air inlet covered if necessary, until the temperature is within operating range. Stop the engine, remove the radiator

cap, and drain the system by opening the drain plug in the transmission oil pan (fig. 27).

(2 ) A llow the engine to cool. Close the drain plug, pour waterslowly into the radiator until the system is approximately half full,then run the engine at idling speed. Add cleaning compound in theproportion of one container of cleaner to every 4 gallons of coolingsystem capacity. Then complete filling the system with water.

Caution: Never mix the water and the cleaning compound before

putting them into the system. Do not spill the solution on skin,clothing, or painted portions of the vehicle.(3 ) Install radiator cap and run engine at fast idling speed, cover

ing air inlet if necessary, until coolant reachesa temperature above180° F. but not over 200° F. Do not drive the vehicle.

(4 ) Stop the engine after it has run for 3 0 minutes at 180° F. butnot over 200°F. Then remove drain plug and radiator cap and drainsystem completely.

(5 ) For information on back-flushing of engines, refer to TM9 - 2 8 5 8 .N E U T R A L I Z I N G .(1 ) A llow engine tocool. Install drain plug,

pour water slowly into the radiator until the system is approximatelyhalf full (20 quarts), then run engine at idling speed. Add neutralizercompound in the proportion of one container of neutralizer to every4 gallons of cooling system capacity. Each cleaning compound container contains a separate portion of neutralizer. Then fill system withwater.

(2 ) With air inlet covered, le t engine idle for at least 5 minutesat normal operating temperature. Then stop engine.

(3 ) Drain system completelyby removing drain plug and radiatorcap.

FLUSHING. (1 ) A llow engine tocool. Install drain plug. Pourwater slowly into radiator until system is approximately half full,then run engine at idling speed and fill system completely.

(2 ) Run engine, keeping air inlet covered if-necessary,until coolantis heated to normal operating temperature.

(3 ) Drain system byremoving drain plug and radiator cap. Repeatflushing operation until drain water is clear.

(4 ) Again allow engine to cool and clean all sediment from radiatorcap valves and overflow pipe. Blow insects and dirt from radiatorcore air passages with compressed air, blowing from the rear. U sewater if necessary to soften obstructions.

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/. LEAKS. After completing the flushing operation, make certainthat engine has been allowed to cool again. Install drain plug. Pourwater slowly into radiator until system is approximately half full,then run engine at idling speed and fill system to2 inchesbelow bottomof filler neck. Stop engine. Examine entire cooling system for leaks.

This is important because the cleaning solution uncovers leakswhichexist but are plugged with rust or scale. Leaks that cannot be corrected by the using arms should be reported immediately to ordnancemaintenance personnel. After leaks have been remedied performbelow.

C O O L A N TS E RV I C E .(1 ) W h e n servicing the vehicle for summer,fill the system nearly full with clean water. Add corrosion-inhibitorcompound in the proportion of one container of inhibitor to each4 gallons of cooling system capacity. Then complete filling thesystem with water.

(2 ) When servicing for winter, fill the system about one-third fullof clean water. Add sufficient antifreeze compound (ethylene-glycoltype) for protection against the lowest anticipated temperature. R efer to paragraph 23 . Add water until system is nearly full, then runengine until normal operating temperature is reached. Then addsufficient water to fill system to 2 inches below bottom of filler neck.

116. Hoses and Connec t ionsR E M O VA L .Drain cooling system (par. 1156). Loosenscrews in

hose clamps and slide hose off ends of radiator, cylinder head andwater pump elbows,and bypass fittings.

6. INSTALLATION.The hoses are installed without gasket paste orsealer. Install clamps on hoses, slide in place on connection elbowsand fittings, and tighten clamp screws securely.

117. Radiator Thermosta tR E M O VA L .Drain approximately 2 gallons of fluid from cooling

system and reinstall drain plug. Open engine compartment door.Loosen hose clamps and disconnect the tw o hoses at radiator inlethousing on top tank. Remove four cap screws and washers holdinginlet housing to radiator, and remove housing. Remove thermostatand discard gasket (fig. 102) .

INSPECTION. Check thermostat by placing it with bimetal coildown on a brick in a pan of water also containing a thermometer.

Caution: Do not place either the thermostat or the thermometer onbottom of pan because of uneven concentration of heat at that pointwhen pan is heated over a burner.

Heat water until thermostat valve begins to open. The temperature at which this occurs depends on the heat range which the thermostat is designed for. S ee tabulated data, paragraph 114. The oper-

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CROSS ANGLE— ' RADIATOR INLET HOUSIN G

G ASKET

VALVE U

RADIA TORUPPER TAN K

THERMOSTAT

BIMETAL SPRING

R ADIATOR TOP TANKRAPD 33 1383

a ting temperatur e is s tamped on the housing flang e of most therm ostats. If the thermo stat does not o pen, or does not open at a temperatur e close to the m a rkings found on the thermostat flang e, it sh ould be repl aced. If the the rmostat does no t open and close completelyand fu nctio n freely, o r is badly rusted , it should also be replaced.

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R ADIATOR INLET C ATT A CHING S C R E W S

ENGIN E COMPART MENT R . H. DO O R ^

A IR IN LE T L— RADIA TOR

GRILLE S C R E E N INLE T AS S EMBLYENGIN E COMPA RT MENT

L . H. DOOR

LIFTING R IN G S

O V ER FL O W P IP E f*

C O O L E R H O S E

•ATT ACHIN GS C R E W S

DIF F E R E N T I A LO IL C O O L E R

C O O L E RM OUNTIN G

B R A C K E T

C O O L E R HOS E

— » * RA PD 331857.

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IN L E T A ND

T HE R MO S T AT

FILLE R C AP 4. HO U SI NG

k U P P E R TA NK

FAN S HR OU D-1

FA N

-O UT LE T E LB OW

FA N S U P P O RT -

U N I V E R S A L J OI NT Y O K E

R A P D 33 1 856

IN S TA L L AT I O N. Pl ace a new ho using ga sket on ra dia tor ta nk ,

and p ositi o n th erm o sta t on ga sket w ith valve ex tend ing in to ra d iato r tan k w it h axis of valve ho rizo n tal (fig. 103). Po sition housing, and in sta ll fo ur m oun ting screws an d washers. U sin g a to rque wrench,tig hte n cap screws to 18 foot-pounds. Reconnect hose to h ousi ng an d tigh ten hose clamps. F ill cooling system and close engine c o mp a rtm ent door.

11 8 . R a d i ato r a n d F an

R E MO V A L. (1) R efer to p ar ag ra ph 115& .(2) Re

move two bolts at ta chi n g an gle p late at rea r o f engine co mp ar tm en tdoors and remove angle p late and doors. Remove five screws h oldin gra diato r a ir inlet assembly to h ull ro o f, and six screw s that hol d inlet to engine com p artm ent cross angle (fig. 104). H oo k sl ing to inl et assembly, a tta ch h oist to sli ng, and li ft rad ia tor inle t assembly offvehicle.

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(3 ) Disconnect radiator overflow pipes at hoseconnection at filler neck and under metal seal at engine compartmentsides, and remove pipes (fig. 105). Eemovefive screws that hold metalseal to radiator cross ang le and remove seal. Loosen hose clamps onrad iator inlet housing at top of ra diator and outlet pipe at bottom

o f radiator, and pull hose off connections. Remove four cap screwsh olding fan shaft universal joint b earing trunnio ns on fan shaft yoke.Slide slip joint back to clear fan shaft yoke. R emove two long boltsthat hold upper part of radiator to center and side su pports. Backout one lo n g bolt hol ding lower part of rad iator to side support.

This bolt cannot be removed completelyuntil radiator has been liftedout.

Working on re ar side of radiator, remove short bolt that holdsrad iator to support at center. Hoo k sling (41-S -3832-82) to liftin grin gs on top of radiator; connect hoist to sling and lif t radiator ,shroud and fa n assembly out of vehicle (f ig. 106) . Tilt radiator forward to clear cross angle with fan shaft yoke. Removeo ther radiatorin same man ner. Removeeight bolts and washers attaching fan spid erto fan shrou d and remove fan. Remove four bolts, nu ts, and washersattaching fan shroud to radiator and removeshroud.

Z > .INSTALLATION.(1) Place fan shroud onradiator and install four attachin g bolts, nuts, and washers. Pla cefan assembly on fan sh roud and ins tall eight bolts and washers attach ing fan spider to shroud. Connect sl in g (41-S-3832-82 ) toradi ator lifting rings, attach hoist to sling, slide lon g lower outer bolt in p ositio n, and lower radia tor in p osition in engine compartment.Tilt top of radiator toward rear of vehicle to clear cross angle with fanshaft (fig. 106 ). In stall one long bolt through u pper part of radiatorand into tapping nut on center suppor t. Screw long lower outer bolt

into side supp ort. Working at rear of radiator, install short boltthrough center support and into tappin g nut on ra diator. Reconnecthose connectionsat radiator inlet hou sing at top of ra diator an d outletho using at bottom of rad iator, and tighte n hose clamps. Line up fanshaft yoke with universal joint bearing trunn ions and install fo ur capscrews and lock pla te s. T ighten cap screw to a torqu e tigh tness of 16to 20 foot-pounds an d lock in place by bending lock plate ears overflat of cap screw. P osition metal seal on ra diator cross angle and

radiator, and install five mounti ng screws with washers (fig. 105).P lace radiator overflowp ipe on to p of radiator, connect short hose atfilled neck and hose un der metal seal at engine com part ment side top ipe, an d tighten hose clamps. In stall overflow pipe clip screw.

(2 ) H ooksli n g on air inlet assembly,attach hoi st to sling, and lift inlet assembly into position on vehicle. Insta ll bolts through radiator inlet frontflange and into h ull roof. D o not tighten bolts. Line up six holes

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between ge nerator and water pump pulleys (fig. 50). H old g eneratorin th is pos ition and tighten generat o r cradle locking nut. Replaceaccess p la te at rear of engine compartmen t. Close engine compartment doors. Refill cooling system.

E NGI F R O NT B A N DI N D I C AT I N GLR O D C A P -- F R O NT BA N DA D J U S T I N GSCREW

ENGINE F R O NT SUPPORT

VACUUM LINE

OIL COOLER WATERINLET LINE WARNING

S IG NAL SWITCH'

FULCRUMLEVER

SIDE COVE RRA PD 331 30 5

BRACKETFULCRUM LEVER

F ULCRUM LEVER CLEVIS P INMAN UAL CONTROL

: CONNECTER LINK -HUL L DRAIN VALVE

-ADJ USTABL E ROD-REAR R ELAY LEVER RA PD 331304

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Sec t ion XXVII. HY D R A M AT I C TRANSMISSIONS

12 0. D e s c r i p t i o n a nd Data

DESCRIPTION. The hydramatic transmis s ion (fig. 108) consistsof a fluid coupling and an automati c hydrau lic-operated transmission having four speeds forward. N o reverse gearing is incorpora ted inthe transmission s as this is provided in the transfer u nit. Slippagein th e fluid coupling a t engine idlin g speeds eliminates the need for a clutch. Gear change s are made automatically by hy draulic pressure, and are governed by the speed of the vehicle and the extent towhich the driver depres ses the accelerat or. In this section, the fluidcouplin g end of the transm ission will be referred to as th e "front"end, and the output shaf t end as the "rear" end.

D ATA .

Clutch type—____ ____ _____________. Fluid cou pling.Nu mber of spee ds__________ _____—__ 4.First speed ge ar ratio _ ____________———_- 3 .92 to 1.Second speed gear ratio________ ________ 2.53 to 1.Third speed gear r atio____ _____________ 1.55 to 1.Fourth sp eed gear ratio___ __ _____—————. 1 to 1.Ty pe gearing _ _____________________ _

. Planetary.1 21. Manual C o n t r o l Li n k a g e Ad j u s t m e n t

GENERAL. The transmiss ion manual cont rol linkage from th eneutral pedal in the driving compartment to the cross shaft und erth e bulkhead is set at assembly of the vehicle, and normally requir esno further adjustmen t. If engines are replaced, or it becomes neces sary to synchronize transmiss ion control linka ge, adjustm ent should

be made at the fu lcrum lever mounting bracket on the transmissionrear bearing su pport (fig. 109) as outlin ed below.5. A D J U S T MEN T P R O C E DU R E . Place tr ansmis sion selecto r lever in

"DRIVE" slot of quad rant (fig. 9). Open door in bul khead extension cov er over transfer unit. Working through opening, lo osenclamp .screw on fulcrum lever a d justing rod (fig. 109). M ovefu lcrumlever and attached levers to the midd le detent p osition. Holding adjusting rod in po sition, tighten clamp screw. Ad ju st other transmission linkage in same manner.

C H E C KA D J U S T M E N Tor B O T HTRANSMISSIONS.Set brakes. Run both engines at same time with tran sfer un it in HIGH and transmission selector lever in NEUTRAL. Se t hand throttle to run enginesat 1,000 revolutions per minute, and move selector lever slowly to wardDRIVE. By wa tc hing tachometers, note position o f lever when speedof one engine drop s. Re ar edge of selector lever s hould be a pproximatel y o ne-eighth in ch in front of front edge of slot in quadrant when

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engine speed drops. Continue m oving lever until speed of other enginedrops. This should be within %-inch ad diti onal lever travel. Ifdifference is greater, readjust fulcrum lever of newly installedtra nsmission.

122. B a n d A d j u s tm e n tGENERAL. T he transmission front band is p rovided with an

adjustment-indicating rod (fig. 110) and can be adjuste d in the vehicle.The rear band is provided wi th an automatic band adjuster anddoes not incorpo rate an indica ting rod. If tests ind icate that there ar band require s adjusting, notif y ordnance personnel.

5. ADJUSTMENTP R O C E D U R E .Remove 18 mounting screws and remove hull rear floor cover under engine and tr ansmission to be checked. Set vehicle brakes, place transmission selector lever in NEUTRALand start engine.

T ransmission should, if possible, be at normal operating tem peraturebefore making band adj u stments.

Working through th e engin e compartm ent floor opening, removetransm ission band indicating rod cap (fig. 108). Run engine for a fewminu tes at idling speed; then move trans mission selector lever to

DRI VE p osition and set hand throttle so that engine is runn ing atapproximat ely 1,000 revo lutions per minu te. Hold a straig htedge or

INDICATING ROD CAP -, FRON T BAND ADJ UST ING S CR E W

-ADJ USTING SCR E W LOCK NU TWARNING SIGNAL SWITCH RAPD 331797

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scale across front ban d indica ting rod boss, and check to see if indicating rod end is flush with rod boss on trans mission case. Band iscorrectly adjusted when ind icating rod end is flush with rod boss ontransmission case (fig. 110). I f band adjustment is incorrect, move lever back to NEUTR AL, loosen band adjus tin g screw lock nut and

turn front band adjusting screw to estimated correct adjustment , movelever aga in to DRIVE, and recheck. Rep eat until indicating ro dend is flush wi th rod boss. Idle the engine. Lockband adjus tingscrew an d recheck adjustment. Install ind icating rod cap, being sureseal is in place.

Caution: Run one engine only, and do not p ull the engine againstthe fluid coupling for more tha n 1 minute at a time, and allow atleast 3 minutes for the oil to cool before repeatin g.

123. Tr a n s m i s s i o n R ep l a c e m e n t

A U T H O RITY. R eplacement of this major assembly with a new orrebuilt unit is n ormally a field maintenance ope ra tion, but may beperformed in an emergency by o rg anizational maintenance un its, p rovided authority for perf orming this replacem ent is obta ined fromthe appropriate commander. Tools needed for the operation whichare n ot carried in org an izational maintenance units ma y be obtained

from a higher maintenance unit.& . R EM O VA L . (1) R emove engine and transmission assembly (par. 6 7).

(2) Removesix screws that holdlower flywheelhousing to upper housing; remove housing and discard gasket.

(3 ) Disconnect solenoid a t terminal onsolenoidrelay. Remove tw o moun ting bolts holding starter to flywheelhou sing and remove starter.

(4) Disconnectright an d left oil coolerlines at tra nsmission oil pan fittings (fig. 108); loosen u pper connections at crankcase and wat er pum p inlet pipe; and move lines out ofthe way. Loosen hoseclamp on hose connecting transmission andengine oil filler tubes at transmiss ion filler side. Remove screw thatholds transmissio n filler tube lower mountin g to transmission case.Removenut holding filler tube upper mounting bracke t to rear manifol d clamp stud, and remove tube. D isconnectvacuum line at fitting

on intake manifold and elbow on transmission case (fig. 108). Removeflywheel h ousing mounting screw holding vacuum line clips, and remove line. D isconnect warn ing signal switch wire a t switch on transmission, and pull conduit o ut of clip on transmission side cover.

(5) Insta ll socket wrench on engine crank sh aft pulley mounting screw and turn crankshaft until flywheel coverdrain plug is at th e bottom. Removedrain plug in flywheel coverand

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in transmission oil pan (fig. 27) and drain transmission. Reinstalldrain plugs.

(6) Install lifting eye (41-B-1586-300) intop of transmission case. Connect hoist to eye and take up weight oftransmission. Remove 3 0 screws that hold flywheel cover to flywheel.

Rotate crankshaft with socket wrench on engine crankshaft pulleymounting screw.

Remove remaining six screws that hold flywheel housing to crank-case and pull engine conduit out of the way. Pull transmission back toslide flywheel housing off dowels in crankcase, and mainshaft pilotout of bearing in end of crankshaft, and remove transmission.

I N S TA L L AT I O N .(1 ) Position new flywheelcover gasket on flywheel.

Caution: Do not use gasket sealer of any kind.Install lifting eye (41-B-1586-300) in transmission case, attach

hoist to eye, and lift transmission into position behind engine crank-case. Push transmission toward engine, entering dowels in crank-case in holes in flywHeelhousing and mainshaft pilot in bearing in endof crankshaft. Install six flywheelhousing mounting screws, placingclips for engine conduit and vacuum pipe clip under upper screws.Tighten screws to 45 to 50 foot-pounds, using torque wrench and

tightening lower screws first.(2 ) Install flywheel cover. Pull flywheel cover toward flywheeland line up dowels in flywheelwith holes in cover. Hold cover inposition and install one mounting screw adjacent to dowels. Turnflywheel 180° (using socket wrench on crankshaft pulley mountingscrew) and install another screw. Tighten these two screws to 12 to15 foot-pounds, making sure that cover seats properly on flywheelandflywheel dowels. Install two screws approximately 90° to dowelsand tighten to 12 to 15 foot-pounds. Install remaining 26 screws andtighten all screws to 25 to 3 0 foot-pounds, using a torque wrench.Then tighten all screws to 40 to 45 foot-pounds, proceeding in rotationaround the flywheel. Disconnecthoist and remove lifting eye.

(3 ) Lift starter into position on flywheelhousing, and install tw o mounting screws through housing and intostarter mounting flange. Connect solenoid wire to terminal on solenoid relay.

(4 ) Connect transmission warning signal switch wire to switch, and push conduit into clip on transmissionside cover. Connect vacuum line to intake manifold and to elbow ontransmission case. Position filler pipe in transmission case and pushupper side outlet into hose connectionon engine oil filter tube and uppermounting bracket over engine manifold rear stud. Install screwthrough lower filler tube mounting bracket and into transmission case.Install nut holding upper tube bracket to manifold stud, and tighten

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hose clamp on transmi ssion to engine filler tube hose. Connect oilcooler lines to fittings on tran smissio n oil pan a nd tighten upper andlower connections.

(5) Ins tall new gas ket on lowerflywheel hous ing a nd lift into position on uppe r flywheel h ousin g and

insta ll six mounting screws.(6) In stall engine and tran smiss ion assembly in

vehicle (par. 68).(7) Install 10 q uarts of engine oil. Start

engine and run fo r approxim ately 5 min ut es to fill fluid co uplin g (fig.28) ; the n add an ad ditiona l 5 q uarts to bri ng oil up to FULL m ark ongage. M ake certain the engine is s topped befo re add ing the last 5q uarts.

124. T o r u s Member Replacem en t

AUTHORITY. Replacem ent of this m ajor assembly with a new orrebuilt u nit is norm ally a th ir d echelon o pe ration, b u t may be perform ed in an emergency by second echelon, provid ed author it y for performi ng this repla cemen t is obtained from th e app ro priate commander.Tools needed for the op eration which are not carried in second echelon may be obta ined f rom a hig her echelon of main tenance.

R E M OV AL . (1 ) Remove engine and transm ission assembly from vehicle (par. 67).(2 ) Remove tran smis sion assembly fro m

engine (p ar. 123a).(3) St raight en mainsha ft nut lock, and

remove nut and lock h o lding d rive n torus member on shaft. Pull

U P P E R F LY W H E E LHOUS ING

SNAP R ING

P L I E R S

SNAP RI NG

INTERMEDIA T E

S H AF T

RA PD 35 3815

MAIN S H AF T

DRIVIN G TORU S

F LY W H E E L COVE R

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VALVE BODY

VA C U U MP I P EC O N N E C TO R G O V E R N O RP I P E S G O V E R N O R SLEEVE

Figure 112. Removing transmission valve body.

driven torus member off mainshaft. Remove snap ring holding driving torus on intermediate shaft, using snap ring pliers (41-P-1992-85)(fig. 111). Pull out on driving torus and remove from intermediateshaft.

INSTALLATION. (1) Push driving toruson splines of intermediate shaft and install snap ring (fig. Ill), usingsnap ring pliers (41-P-1992-85). Push driven torus on transmissionmainshaft splines, and see that oil pressure regulator on inner hubslides over end of intermediate shaft. Install driven torus retainingnut and new lock on mainshaft and bend lock back over nut.

(2) Install transmission assembly on engine(par. 1 2 3 & ) .

(3) Install engine and transmission assembly invehicles (par. 68).

125. Valve Body

REMOVAL. (1) Remove screwsfrom hull floor cover under transmission.

Caution: Support rear end of cover while removing last screws toprevent cover from dropping down and causing injury.

Front of cover is held up by hooks on cover. Slide cover towardrear of vehicle and lower to ground.

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lever mounting bracket to transmission, making sure holes in bracketline up with locating dowels on transmission. Install tw o attachingscrews and tighten securely.

(3 ) Connect and adjust linkageat fulcrum lever mounting bracket (par. 122&).

(4) Coat edges of floor plate with jointand thread compound (cement, type II) and place gasket on plate.Kaise front edge of plate until hooks on plate rest on hull floor.Raise rear end of plate, and line up screw holes with drift punch.Install floor plate retaining screws.

Section XXVIII. PROPELLER SHAFTS AND SUPPORT BEARINGS

126. Descr ipt ion and DataC O N S T R U C T I O N .There are three propeller shafts used in this

vehicle. The main propeller shaft extends from the transfer unitforward to the controlled differential. Two final drive propellershafts extend from the controlled differential, one on each side, tothe final drives. The main propeller shaft is of welded steel tubeconstruction. The final drive shafts are made of two forged yokeswelded together.

Z > .M A I NP R O P E L L E RS H A F T. The main propeller shaft is providedwith a yoke for the universal joints welded to each end. The rearuniversal joint yoke is splined to provide a sliding joint with the

B U L K H E A DE X T E N S I O NFELT T R A N S F E RUNIT T R A N S M I S S I O NS E A L AND R E TA I N E R S SHIFT LEVER / E L E C TO R LEVER

T R A N S F E RUNIT SHIFTER MAIN PROPELLERS H A F T C O N T R O L L E DDIFFERENTIALSHAFT E X T E N S I O N (SHIELDS R E M O V E D ) RA PO 331821

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transf er unit mainshaft, and the front yoke is spline d to fit on the di fferential pin ion shaft.

F I N AL DRIVEPROPELLER SHAFTS. The final drive prope ller shaftconsis ts of tw o forged yokes w el ded together. The yokes on ea ch side of the co ntrolle d differential are splined to the o utput shafts, an d are

a slip fi t to compensate for m ove ment of the unit and to prov ide cl earance whe n re mov ing the sh af ts. The yokes on the final driv e inputshafts ar e also splined, b ut are held on th e shafts by a la rge nut andcotter pin .

TU N N E LA N DG U A RD . The m ain p ropell er shaft is mounte d in a. tu nnel form ed b y metal shields on each side, supp orted by b racke ts

attached to the hul l floor and sealed at the rear by a baffle bolted to theh ull floor and bul khe ad ex tension. The top of the propel ler sha fttunn el is cov ered by the peri scope stow age box. The final

dr iv e p ro

peller sha fts are protec ted by sheet me tal shields whic h fit aroundthe shafts an d universal joint s, and a re bolte d together at m ou ntingbrack ets on the contr olled diff erentia l an d final driv e cases. L egguard s are m ounted on the fin al dri ve housin gs . A ll guards ar e easi lyrem ovab le for service wo rk.

TRANSMISSION—TRANSFE R U N I T. The conne ction betw ee n eachtransmission and t he transfer uni t is made by two universal joi nts anda coupling block. The tran smis sion output sh af t carries the rea rmo styoke, and the foremost yoke is a sliding spline fit int o the short transferunit inp u t shaft.

/. DATA.Propeller shafts , number used_ _ 3Propeller shaf ts, type___ ____ Welded tube and welded forgings. U niv ersal jo ints, n umbe r used__ 10.Universa l joints, t ype__ _____ N eedle bearin g.Universal join ts , m ake_____ _ M echanic's.

127. Main Pro p eller Shaft

R E MO VA L . (1) R emove fourcap screws ho lding periscop e stowage box to support brack e t an d liftbox from its p o sition.

(2 ) Remove one screw holding this gu ard in p osition a nd l ift out guard .

(3) Rem ove lock wires an d fourcap screws h olding the fro nt propeller sha ft universal join t bearing h ou sings to yoke, p ry propeller shaft back to tele scope rear yoke ontran sfer uni t sh aft, and brea k jo int.

(4 ) Lift propel ler shaft u p a nd pull offfrom tr ansfe r unit shaf t. Remove sha ft fr om vehic le through thedriver's do or. Use care no t to damage oil seal surfa ce of sl iding yoke.

5. INSTALLATION. (1 ) L ower

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propeller shaft into the vehicle through driver's door opening. Slideyoke on rear end of shaft through seal and over splines of transfer unitoutput shaft.

(2) Raise front end of shaft andtelescope shaft on transfer unit output shaft until sufficient room is

provided to connect front universal joint. Line up bearing housingswith yoke on controlled differential pinion shaft. Install four capscrews, tighten to 8 5- to 95-foot-pounds torque, and install lockingwires.

(3) Install left propeller shaftguard and fasten in place with one screw.

(4) Place periscope and spare headstowage box in position on support brackets and fasten securely withfour cap screws.

128. Final Drive Propel ler Shafts

REMOVAL. (1) Remove four capscrews holding propeller shaft shield to mounting brackets on controlled differential and final drive housing and remove shield.

(2) Remove locking wire andfour screws (fig. 114), holding universal joint bearing housing toyoke on final drive input shaft. Slide propeller shaft toward differential as far as it will go and disconnect universal joint.

FINAL DRIVE P R O P E L L E RS H A F T RA PD 331385

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(3) S lide pr opeller sh aft toward side ofv ehicle to pull yok e off differenti al output sha ft, an d re move propel lershaft assembly from vehicle.

INSTA LL AT I O N . (1 ) L ower p rop ellers haft assembly in to vehicle. Lif t shaft into posi tion. Enga ge yoke

on d if ferential outp ut shaft spline and push yoke into d ifferential asfar as possible. Line up ho les in beari ng h ousing with hole s in yokeon final drive inp ut shaft, a nd in stall fo ur screws holding ho using s toyoke. Lock wir e through th e screw h eads, toget her in pairs.

(2) Po sition prop e ller shaft shields around shafts,and install four screws hold ing shield to b ra ckets on controll ed dif ferential and final drive h ousing.

Sec t io n XXIX. TRA NSFER U N I T1 29. D es c r i p t io n and D ata

DESCRIPTION . T he transfer u nit is mounte d on su pport bracketson the h ull floor between an d parti ally ahead of the two trans missions .The tr ansfer unit per fo rms two functio ns: It combines the powe r ou tput o f the two engine s; a nd it provid es two speed rang es forward andone in rev erse, a ll of which are manually selected. Eac h tra nsfer unit

input gear is co nnected to the input shaft by m eans of a sliding coupl in g, whi ch in turn is conne cted to th e inp ut clutch lever on the outsid e of th e case. This arr angem ent perm its disconn ecting either oneof the eng ines if an engine is d isabled, so th at the vehicle ca n be drivenby one en gi ne witho ut the drag of the disa b led eng ine.

D AT A .

Number of sp eeds forward__ ___ _____ 2.Nu mber of speeds reverse_ ____ _____ 1.

Gear ratio in L OW______ _ _______ 2.34 to 1.G ear ratio in HIG H_________ _____ 1.03 to 1.

Gear ra tio in EEVEK SE__ ______ __ 2.44 to 1.T ype of gears.. _ _________ __ ____ Helic al.Type of shift____ __ ________ __ __. Manual, sy nchro-m esh.

13 0 . Tr a n s fer U ni t Shi f t L ever

D E S C RI P T I O N . T he transfer un it shift lever is mounted in abracket b olted to the hull floor at the rig h t side of the dr ive r's seat(fig. 115) . Wh en the lever is moved to the left an d pushe d forw a rd,the lowe r end of the lever engag es the rev erse a rm and le v er assemblywhi ch is conn ected b y ro ds to the reverse gear shifter shaft ass embly. This sl ides the reverse g ear clutch along the mainshaft, locking thereverse gear to the mai nshaf t. When the shift lever is m oved to theright and pushed for w ard or b ackward , the lower end of the shift lever

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SHIFTERS H A F T E X T E N S I O N-, SHIFT C O N T R O LLINKST R A N S F E RUNIT

SHIFT LEVER

"HIGH" AND"LOW"

SHIFT LEVEI

CONTROLLEVERS H A F T

SHIFT LINKC L E V I S P I N BOLT AND NUT.

llSPRING AND G U I D E

RA PD 331854

engages the arm and lever assembly for the HIGH and LOW shifter

shaft. This moves the high and low gear synchronizer clutch alongthe mainshaft to engage the gear selected by the driver.

REMOVAL. (1) Remove four screwsholding the box to the four supporting brackets and one screw holding box to bulkhead extension at right side. Push transfer unit shiftlever to the REVERSE position and remove box assembly.

(2) Lift up on spring guideto compress spring until guide clears hole in shifter lever cross shaft.Remove spring and guide (fig. 11 5 ) .

(3) Remove nut and washerfrom shift lever clamp bolt and remove bolt.

(4) Slide shift lever cross shaft out ofsupport bracket toward driver's seat.

Caution; Arm and lever assemblies and spacer washers will dropdown when shaft is removed.

Note position of parts before removing shaft so they will be reinstalled in the proper sequence.

(5 ) Tilt top of lever toward rightside of vehicle so that bottom part of lever comes out of side of support bracket. Raise driver's seat to allow room for removing lever.

INSTALLATION. (1)Slide top of shift lever through opening in left side of support bracketso that top of lever comes out through opening on quadrant.

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r XTENSIO N CLAMP S CREWS

"H IGH" AN D "LO W-

GE AR SHIFTER SHAF T

REVERSE GEAR

SHIFTER SHAF TSHIF T CONTROLLINK ADJU STERS

SHIFTER SHAF T / AD J U STER LOCK NUTS

EXTENSION

TRANSFER UNIT SHIF T LINK

RA PD 3 31 853

EVER

CLAM P SCR EW" TRANSFER UN IT~ ^ RA PD 33 1299

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(2) Slid e sh if t lever cross sha ftthrou gh ope ning in sup por t br acke t.

D o not slide shaft all the way in.

Raise R EVER SE lever an d arm assembly, and slide on end of sh iftlever cross shaft. Next, place one of the spac er wa shers on sh a ft andslide shaf t throug h hole in shift lever. Install anot her sp acer w asherover shift lever shaf t. Ra ise HIG H and L OW lever and ar m assemblyup into position. S lide shaft throug h this arm also. Insta ll the last spa cer was her over the sh ift lever sh a ft and slide shaft into other endof support bracket. L ine up notch in shaft with hole in bra cket an dinstall clamp bolt, nut, and washer.

(3) Slide sprin g and guid eonto pin on sh ift lever. Compress spring on g uid e so tha t gu ide willenter cu t-out on shi ft lever cross shaf t.

(4) Pl ace trans fer unit sh ift lever in reverse p osition to allow room to install box. Slide box into pos ition onth e four sup porting bra ckets, an d instal l four screws and washers at suppo rts and one screw a t bu lkhead extension.

LINKAGE ADJUSTMENT. (1) Move shif tcontrol lever from HI GH to LOW and from LO W to N EUTR AL

to locate by feel the mi ddle of the neutr al de tent position. Shiftlever should now be in l ine with gate in quadra nt oppositeNEUTRA L . If it is not, re ad just as ex pl ained below. When HIG H -LOW s h ift rod is pr op erly adju sted, move shift lever throughg ate tow ard driver. S lot in bottom of sh ift lever should line upw ith lug on reverse lever and arm assembly. If it does not, readjust reverse shift rod as explain ed below.

(2) Remove five screws ho lding the box

to the four sup p orting brac kets and bu lkhead. P us h transf e r unitshift lever to REV ERS E po siti on and remove box assembly.(3) Loosen lock n ut on sh ift link an d

turn thread ed adju sters (fig. 116) in or out u ntil the shi ft lever is in the c enter of th e gate in th e quadrant when the H IGH-LOW shiftrod i n the NEU TR AL d et ent position. Tighte n lock nut on shiftlin k.

(4) A fter HIG H-LOW shift rod hasbeen adjusted, ad just REV ERSE shi ft rod in same m anne r so thatthe sl ot in th e botto m of the shif t lever will be in lin e with the lugon reverse lever and arm assembly . Shift lever should engage H IG Hjind LOW lever, and R EVERS E lever witho ut interfere nc e.

(5) P osit ion tra nsfe r un it shif t lever inREVE R SE. Slid e periscope box into positio n on four suppo rtingbrack ets and in stall attach ing screws.

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131. Engine Inpu t Clutch Lever

DESCRIPTION. T wo inp ut clutch levers, one for each eng ine, a remoun ted on vertical shafts on ea ch si de of the transf e r unit. When a leve r is in the rear pos ition, the sli d ing clutch 01 1 th e in put gearis engaged wit h the input shaft. W he n the lever is moved forward ,the slidin g clutch is dis connected.

& . RE M O VA L .O pe n sliding doo r over top of tra nsfer unit and ra isescreen. Re move input lever clamp screw and lif t off lever (fig. 117).

INSTALLATION. Place input du tch le ver over in put clutch shaft and install clamp screw. Close screen and sliding doo r over tran sferunit .

132 . Trans fe r Uni t Rep lacem ent

A UTHORITY. Repla ce ment of this m a jor asse mbly w ith a new orrebuilt u nit is normally a field maintena nce operation, b ut may beperformed in an emergency by o rga nizational ma in tenance units, provided author ity for pe rforming this rep lac ement is obta ined fr om theappropr iate commander . Tools n eeded for the op eratio n which arenot c arried in organ izational m aint enance units m ay be obtained froma hig her m aintenance unit.

& . R EM O VA L . (1 ) Re fer to paragr aph 67.

(2) Refer to paragraph 118a.(3 ) Rem ove fou r screws holding

lower radiato r seal to engine bulkh ead. L ift out seal.(4) W orking from dri ving

compartm ent, rem ove two scre ws hold ing center radiator support tofront of en gine bulkhead. Remo ve four sc rews holdi ng cen ter radiator supp ort to rear radia tor support. Lift ou t support.

(5 ) Remove fo ur clamps

holding p ip es to hull floor. Disc onnect low er center fire ex tinguisherp ipes at hull sid e wall connections, and remove screws h olding centerbr acket to hull floor. Re move pipe s as an assembly.

(6 ) Disconnect an d remove interm ediate-to-rear throttle re lay rod and rea r relay as an assembly.

(7) Rem ove eigh t screw sholding engine front rubbe r cu shions to engine front suppor t bra ckets and remov e cushions.

(8) R emove shi fter sha ft extension clamp screw th a t locks extension to shifter sha ft (fig. 116) .Driv e a small wedge or a chisel in s lo t in extensi on un til extensio n isfree on shaf t. Move shif ter leve r towards HIGH to sl ide extensi onoft' h igh-low shi fte r shaft and towa rds REVERS E to slide extensio noff revers e shif ter sh aft.

(9 ) Remo ve four screws which attach sh ifter sh aft seal to bulkh ead extensi on an d pull

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seal away from bu lkhead enoug h to c lear trans fer unit h ousi ng atshif ter s haft (fig. 113). I t is not necessa ry to discon nec t othe r l inka gean d rem ove seal comp letely.

(10)To provid e ad ditio nal cle ar ance, rem ove four screws hold

ing sea l reta iner halves to b ulk head ex tension and remove re tainers.Seal is split an d m ay be rem oved from yoke if con dition ind icatesnecessity.

(11) Attach a rope sling a ro und tran sfe runit as sh own in figu re 118. Kemove the th ree transfe r unit mou ntingscrews. A ttach cha in ho ist to r ope sling , a n d take up weight of trans fe r unit . Eaise tra nsfer unit and slide towa rd rea r of vehicl e untilprope ller shaft univ ersal joi nt yoke slide s off splin es of tran sfer

unit outp ut shaft. K aise trans fer un it an d remove f rom v ehicl e.IN ST A LL AT I O N . (1 ) At ta ch a

rope sl ing a round tra nsfer u nit, bein g sure that it is tied as s hortas possible (fig. 11 8) . Th en co n nect cha in hoist to un it. Lowe r unitinto vehi cle. Bef or e loweri ng unit all th e w ay int o p osition, slideprope lle r shaf t rea r yoke on to tr ansfer unit ou tpu t shaft, an d alsop lac e th e two shifte r sh aft extensi ons over th e two shi fter shafts . Sli de tra nsfer unit forw ard until i t rests on the ru bber c ushion sup

po rts. Kemove hoist an d ro pe sling .(2) Install two f ront a n d one rear transfer uni t mo unting screws and tighten securely.

(3) P ositio n sea lover shif ter shaft an d instal l four screws atta ching seal to bulk headextension (fig. 11 6) .

(4) Ins pec tco nditio ns o f felt seal a t propeller shaft yo ke and repla ce with new se al if found to be badl y wo rn or d amaged. S eal

is spl ita

tan

ang leto al low rem ov al or r epla cement wit h out remo ving p rope ller shaftyoke . In stall seal around pr opeller shaft yok e and pos ition meta lreta iners arou nd seal. Insta ll fou r screw s a tta ching r etainers to bu lkhead exte nsion .

(5 ) If ex ten sions were not positione d on shift e r shafts wh ile low erin g tr ansfer u nit to fina l posi tion,move trans fer unit sh ift lever an d at the sam e time sl id e shift er sh aftextensions onto shift er shafts. In stall sh ifter shaft e xtentio n cl a mpscre w at both ex tension s an d tighten clamp screw securely.

(6) R efer to p a ragraph 130e?(3).

(7) Low er fire exti nguis herpi pe into pos ition at rea r of transfe r unit . Ins tall two sc rews ho ldin gc e nter brack et to hull floor , and conn ect pip es to coup lings o n hu lls id e wall. Install four clamps an d screws.

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(8) Install in termedi ate to re ar rel ay ro d and re ar rela y .

(9 ) Pla c e the f our e ng inefro nt rub be r cushio ns on the front engi ne su ppo rt mo untin g b racke ts, and install e ight sc r ews an d lock w as hers.

(10) Slide low er end of c enterrad iat or su pport th roug h s lot in bu lkhead an d insta ll two m ou nting screws. Posi tion upper end o f su p port a g ainst re ar radiat or supp ort,and inst all four screws a nd wa sh ers.

(11) Pla ce low er radi ator seal in p osition in o pening . Ins tal l four screws and w ash ers hold ing seal tobul kh ead.

(12) Kefer to pa rag raph 1185.(13 ) Kef er to

para gr aph 68.

ENG IN E COMP AR TMENT

CROSS ANGLE

T R A N S F E R U N I T

FRONTMOUN T ING

C U S H I O N

DIFFERENTIALO IL CO OLER

O IL FILLERTUB E

REAR MO U N T I NG BR A C KE T ""

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C O N T R O L L E DD I F F E R E N T I A L R . H. ADJ USTING H O L E P L U G

W R E N C H(41-W-642-200) ON L . H. A D J U S T I N GN U T RA PD 331326

7wofc«

Section XXX. CONTROLLED DIFFERENTIAL

133. Descr ipt ion and Data

DESCRIPTION.The controlled differential, located at the front ofthe vehicle, transmits engine power to the final drive units and, inaddition, contains the brake drums and bands that permit steering andstopping the vehicle.

D ATA .Brake rims, number used________________ 2.Size—_———_—_____________________ 15 by 41/4 inches.Brake linings, number per rim___________. 3 .Size—————_—__———_______________ 13 by 4 inches.Differential gearing, type_______________. Spur.Differential, ratio__________________ 1.92 to 1 max.Drive gearing, type___________________ Spiral bevel.Drive gearing, ratio___________________ 2.62 to 1.

134. Steering and Brake-Band A d j u s t m e n t

GENERAL. The steering and brake-band adjustment compensatesfor lining wear. The steering and brake bands should be adjustedwhenever required by lining wear, or whenever the controlled differential is removed and installed.

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A D JUS T M E NT P R O C E DU RE . (1 ) Remove b and adj u sting ho le plu g from each sid e o f contro lle d diff erentia l.

(2 ) Insert socket w renc h (41- E-64 2-20 0) throug hplug hole and en gage adjust in g nu t (fig. 119). T urn adjust in g nut

clockwis e to tig hten ba nd.Br ak e ba nd a djus ting nut lias a c ylindric al surfac e on pres sure side

instead of the us ual fla t fa ce. It is impo rtan t tha t thi s adjustm e nt be m ade by o ne -half tu rns only, so th at th is cylindr ical surfa c e will al ways be sea ted firmlyagain st cro ss p in when a djustmen t is completed.

(3) C heck adju stm ent by p ullin g back on steeri ng lever. T he ad ju stmen t is corre ctw h en tw o condit io ns pre vail : Fi rst, brak e band m ust be free wh en

le ver is in full forw ard pos ition. To make second check, plac e a sp rin gscale at the cente r of rub ber g rip on end of s tee ring leve r and p ullback on lev er u nt il a fo rce of 12 to 15 pounds is exert ed. In th isp os ition, s teering lev er should be six n otc hes b ack from forwa rdposi tion on q uadran t.

On new b ands, lever should only move bac k five notches a t a press ur eof 12 to 15 pou nds.

Repea t check for other brake b an d. If no spri n g scale is avai la ble,adj us tment m ay be made by obse rv ing the foll owin g preca u tions:Firs t, brake ban d mu st be fre e when lever is in full fo rward (r el eased) po siti on; second, lev ers sh ould no t pull back mor e tha n five or si x no tche s under norma l s teering pressur e ; and th ird, lev ers sho u ld notpu ll b ack m ore tha n th ree ad dition al n otch es unde r ful l s teerin g o rs top ping pressur e .

Bra ke s adjus ted on th e "loose side" w ill not only last longe r, but wil l prev ent "glaz ing" of ba nds and pr ovide ea sier steer ing.

(4) Inst al l both band ad justin g holepl ugs in d ifferen ti al case.

13 5. S teer in g a nd Brak e Shoes

REMOVAL. (1) Remove 18 scr ew s ho ldin g differ ential op en ing co ver to hu ll fr ont pl ate. A ttachhois t to lifting hand les on fron t cover. Remo ve cover and g aske t and discard gasket .

(2) Re move 18 screw s that h o lddifferen tial case cover to diff er ential ho usin g. L ift off cove r a nddi sc ard ga sket.

(3) B ack off adjustin g nutand rem ove nut . S lide yoke ou t of stee ring bra ke sh aft pin and remove ten sion spr ing an d washe r; then remov e b ra ke sh aft pin. R emove cott e r pin an d slide out pi n h o lding l ink to b rake shoe.

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(4) Grasp bra ke shoe ass embly wit h b o th hands and pul l out of h ousing , permit ting shoes to rotate aro un dbra ke drum . Repea t steps (3 ) and (4 ) for remova l o f other bra keshoe assembly .

INSTALLATION . (1) In sta ll brake

shoe as semb ly by rotati ng assembl y arou nd b rake rim.(2) Line up p inhol es in steeri ng br akelink and holes in shoes. Slide link to shoe pin int o position andinstal l co tte r pin.

(3 ) P lace s teerin g yo k e to sha ft p in in positio n in stee ring b rake shaft. Slide ten sio n spring and wash er overyo ke and pu sh yoke thr ough steer ing b rake sh aft pin. Install ad jus ting nut on end of yoke. Repe at ste ps (1 ) to (3) fo r o ther bra keshoe as sem bly.

(4) R efe r to par agra ph 134.(5) Pla ce a new diffe ren tial case

cover gaske t on differe nt ial case. Coat gask e t wi th join t and thre adcomp ound (ce ment, ty pe II) . P lace cover o ver gasket an d ins tal l 18screws and w ash ers holdi ng cover to case. Usin g a torque wrench ,tig ht en the five V^-inch scre w s to 80 to 85 foot-po u nds, and th e thirteen% G-inch scr ews to 45 to 50 foo t-pou nds.

(6 ) Plac e a ne w gask et o v ered ge o f hull o pen ing, att ach h oist to co ver, and lo w er into po s ition onfront of hull. Line up sc rew holes w ith d rift p u nch an d install 18 cover at taching screws. Rem ove the ho ist. Using a to rque w rench,tigh ten screws to 80 to 85 foot-p ound s.

136 . Oil Pu m p and Screen

REMO VA L . (1) D rai n oil by re m oving sm all plate under h ull floor at fro nt of vehi cle and rem oving diff erenti al dr ainpl ug. Allow oil to dra in and reinstall p lug and pla te.

(2) Refer to p aragrap h 127a (1).(3) Remo ve four screw s and

w asher s and remo ve pr op eller sha ft guard .(4) Remove two screws

and w ash ers holdin g right f ront propeller s ha ft gua rd support to h ullfloor. Remo ve the suppo rt.

(5 ) Remove seven screws and wash ers holding

oil pum p to differ entia l case (fig. 120). Then remo ve pump .(6) Remove sc rew holdin g oil p ump

st rain er to in side o f diff erential ca se; sli de str aine r do wn toward bo ttom of case and lift out of oil p ump openi ng (fig. 120 ).

(7 ) Cut lock wire an d rem ove win g nut from b ottomof oil pump stra iner ass embly and remov e cov er and stra iner screen .W ash all par ts in solven t and reass emb le.

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DIFFERENTIAL CASE -

. O IL PUMP OP EN ING L_ OIL STRAINERSCREW

C L O SE- UP W ITH P U M P RE M O V E D

OI L STRAINER

O IL PUMP M O U N T IN G

SCREWS__ , _ DIFFERENTIAL CASE

A N ' >

O IL PUMP

OIL COOLER LINE FITTING

E X TE R IO R VI E W — P U M P AN D L IN E S

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INSTALLATION. (1) Lower oil strainerrhrough oil pump op ening and slide pipe on strainer into differentialcase, making sure rubbe r gasket is on end of p ipe. In sta ll screw andwasher holding oil pump str ainer to case.

(2 ) Plac e a new oil pump gasket on oil pu mp

body an d position pump on differ ential case. Install seven screws andwashers h old ing pump to case.

(3 ) Place propeller shaft guard suppo rt over mounting holes on hu ll floor, and install two screwsand washe rs.

(4) Position r ight propeller shaftguard agains t supports and install four screw s and washers.

(5) Refer to pa ragraph 1 276(4).

(6 ) Refer to paragraph 36 .

137. O il Coo l er

REMOVAL. (1) Elevate the howitzer tube tomaximum elevation.

(2) Re move 11 screws from each end of air inlet assem bly and lift ou t assembly (fig. 10 4).

(3) Disconnect both coo ler hoses at bulk

head connection by hol din g hose stationary with one wre nch an d turning coupling with anothe r wrench (fig . 121) . Plug ends of hoses im media tely to prevent oil from runnin g out over radiators.

Radiators will clog with dus t quickly if oil drips on them.

(4) Wh ile a helper supp orts coole r fro m to p ofvehicle, remove fo ur cap screws on fighting compar tment side of bulkhead that hold moun ting bracket s to b ulkhead. Lift out cooler.

(5) Afte r cooler has been removed fr om ve

hic le, turn on one end to d rain oil from unit, and then remove bothcooler hoses from ends of cooler by unsc rewing hose connec tions.

6 . IN STALLATION. (1) Coat threaded end of cooler hose fittings w ith gasket paste, and then install in fitting on endof cooler.

(2) Lower coole r ass embly into position over fro ntof rad iators until holes in cooler brac kets line up with ho les in bulkhead. While helper holds cooler in this position, install four oilcooler mounting sc rews from insid e ve hicle.

(3) Connect both oil coo ler hoses toconnectio ns on bulkhead.

Use two wrenches to connect coupling to keep hoses from twisti ng121 ).

(4) L ower air inlet assembly into posi tion in opening a nd install 11 attaching screws an d washers. Depresshowitz er tu be.

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1 38. Co n trolled Differen t ial Re placem e n tA U T H O R I T Y . Rep lacem e nt of this m ajor as semb ly wi th a new

or reb uilt un it is n orma ll y a field mai nte nan ce op e ration , bu t m ay be per formed in a n emer gency by org an izati on al m ainten an ce u nit,p rovi de d autho rity fo r perf or ming th is rep lacem ent is ob tain ed fro m

the app ropria te com m ande r. Too ls ne eded fo r th e o per atio n whi ch ar e no t c ar ried in org anizati onal m ainten an ce u nit ma y be o btained fr om a h igh er m ainten ance u nit .

R E M O V A L . (1 )(2 )(3) Re lea se brak es an d pu sh

lev ers for w ard to the ful ly rele ased p o sition . Rem ov e co tter p in s andcl evis p ins h olding righ t an d le ft stee rin g an d br ak ing co ntrol rods

to lowe r end o f re lay on con tro lled diff er entia l h ou sing (fig. 1 22) .(4 ) Gra sp en d of pu ll-back sp ring with

heavy plier s an d p ul l bac k u nti l sprin g is c lear o f rel ay (fig . 122).Rele ase spri ng gr a dually unti l i t is fre e . Le ave fro nt end of sp ringco nnect ed to h ull fr o nt pla te.

(5 ) Re mo ve screw ho ld ing lef tp ropelle r s haft guard to sup port b rackets and re m ove guard.

(6 ) R em ove fo ur scre w s h ol din g rig ht propel ler sha ft gu ar d to

su ppo rt b racket s and remov e gua rd.

E A D

V

.COO LE R MO UN TING BRAC KE T J R A PD 3 31325

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(7 ) Kemove cotter pi n and sl ide sto plight switc h rod off pi n on relay arm (fig. 122). Re mo ve two scre wsho lding sto p ligh t sw itc hes to fro nt diffe rent ial mounti ng b rackets .L ay switches to one side so they will n ot be damag ed.

(8 ) Drain oil by re movin g sma ll p la te under h ull floor

at front of veh icle a nd remove differe ntia l d rain plu g . After o il has d rained, reins tal l plu g.(9) Di sconnec t oil cooler line s at rig ht

rear corne r o f d iffere ntial by uns cr ewing co upling on l ine from fit tingon ho using (fig. 120) .

Ca u tion: Pl ace ra gs or co nta iner un der lines to catch any oi l thatmay drain out o f coole r lin es.

(1 0) R emov e fourscrew s h olding both hal ve s o f final d rive prope ller shaft shields to mounting b rackets. The n remo ve th e sh ie lds. Re mo ve two scr ewsho ldi ng shield b rackets to sid es of co n trolled diff eren tial hou sing andrem ove bracke ts.

DIFFE R E N T I A L MOU N TING BOLT S

R E T R A C T I N G S P R I N G S P E E D O M E T E R C A B L E

S TO P LIGHT S W I T C H S T E E R I N G S T E E RING BRAKE L H. P R O P

CONTROL R O D C ON TROL LIN K I N T E R M E D IATE R E L AY S H A F T G U AR D

122.

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(11) Eemovelock wires fro m inn er un iver sal joi nt bearing ho using screws. Eemove fou r scre\vs hold ing univ er sal joint b earing h ou sings to con trolled differen tia l yoke. S lide yoke int o cont rol led diff e rentialh ousing and disc onnect joint.

(12)R emo ve lock wires from front univ er sal join t bearing caps. Remov efou r screws ho lding be arin g caps to d iffer ential yoke. Sli d e propeller shaft back , teles copin g rea r yoke on t ransfer un it output shaft anddisc o nnect join t.

(13) D iscon nect s peed omete r cable(fig. 122) on diffe rential by unscr e wing knurl ed nut on cable an dpullin g core out of case. Remove cable from s lip on case and laycab le to one side.

(14) Re move tw o fr ont an done rear differ entia l mo u nting bolts and nuts and remove bolts.

(15) At tach c hain hoi st to liftin g b racket on dif feren tial cover. Tak e up weight o f differe ntial on hoist u n til it clears mo u nting brac kets on h ul l floor. R aise differen tia l very sl owly ,and see that it does not str ike instrumen t panel (fig. 123). Removediff er ential and lower to gro u nd. Rem ove chain h oist.

INSTALLATION. (1) Attach achain hois t to lift ing br acke t on differe ntial cover. Raise dif feren tialover ope nin g in h u ll front deck. Low er ass embly, b eing car efu l thatit does not st rik e instrume n t panel. Lower ass em bly on support brac kets. Remove chain h oist from cover.

(2) Install tw o fro nt and onerear di ffere ntial moun ti ng b olts throu gh boss on differe ntial case andbr ackets on h ull (fig. 122 ). Inst all nuts and w ashers and tighten nut sto 200 foot-p o unds, usin g a torque w rench.

(3) Plac e sp eedome ter cable in clip on diff eren tial case. S lide speed om eter core int o drive sha ft sleeve an dinstall knurled nu t holding cable to sleeve.

(4)Slide p ro peller sh aft forward , line up u nive rsal joi n t an d inst all fourscre ws h old ing bear in g journa ls to diff ere ntial yoke. Using a torquewre nch, tig ht en screws to 80 foo t-pound s. Lock screw s in pa irs w ithlo cking wire .

(5) Raise propell e r sha ft and pos ition fin al drive be ar ing cap s on diff eren tial driv eyokes. Install sc r ew s holdin g beari ng caps to yoke. U sing a to rquewren ch, tighten scre ws to 80 fo ot-poun ds. Loc k scre ws in pairs withlocking wi re.

(6) Insta ll bra ckets holding prop eller s haft shiel d s to s ide o f differe nti al hou sing. Po sition

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upper and lower sec tion of propeller shaft sh ield over mounting bracketand install eight screws and w ashers.

(7) Insert oil co oler lines into fittings incontrolle d differe ntial case and connect coupling on lines to fittingsinc ase (fig. 120) .

(8 ) Fill controlled differentia l withapproximatel y 20 quarts of eng ine oil. Reche ck level on gage.(9) Place stop light switches in posi

tio n on front differential mounting brackets an d install f our screw sand washers. Slide rod o ver p in on steering and braking relay andinstall flat wash er an d cotter pin (fig. 122).

(10) Place right propellersh aft guard against supp ort brackets and install four sc rews and

washers.(11 ) Place lef t propeller guardagainst sup port brackets and perisco pe stowa ge box, and install screwand washer.

(12) Make sure front end of spring ishooked to bracket on hull front plate. Pull back on end of spring

LIFTING EY E

CONTROLLEDDIFFERENTIAL

FINAL DRIVE Y O K E

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with large pliers, and hook end of spring over cut-out in steeringand braking lever relay (fig. 122) .

(13) Line up hole in connecting rod yoke withhole in lower steering brake relay. Install clevis pin and cotter pin.

(14) Adjust length of connecting rod to permit

free assembly of pin at steering lever by loosening lock nut and rotating clevis. Turn clevis one-half turn tighter to assure taking out allslack, and tighten lock nut. Connect rod to lever and install clevispin and cotter pin. Adjust other lever in same manner.

(15) Refer to paragraph 1 3 4 & .(16) Refer to paragraph 130c.(17) Refer to paragraph 1356

(G).

Section XXXI. FINAL DRIVE

139. Descr ipt ion and Data

DESCRIPTION.The final drive units are mounted in separate housings bolted to the front of the hull on each side (fig. 125) . The finaldrives are designed so that they are interchangeable right to left andcan be installed on either side of the vehicle. Power is transmitted tothe final drives from the controlled differential through short pro

peller shafts having large universal joints at each end. The herringbone gear set provides a reduction ratio of 2.94 to 1. Power outputis through the sprocket shaft, which carries the track driving hub andsprockets.

& . DATA.Bracket_____________________. Cast steel.Cover________._________________ Cast steel.Gear ratio___________________ 2.94 to 1.Sprocket, teeth________________. 13 .Type of gear_________________. Spur (herringbone).

T40. Sprockets and HubsR E M O VA L .(1 ) Break track below and to the rear

of final drive, and lift track over and to the rear of hub and sprockets(par. 144) .

(2 ) Remove 10 nuts attachinghub to shaft and remove hub and sprocketas an assembly.

(3) Remove13 screws attaching each sprocketto hub and remove sprockets.

I N S TA L L AT I O N .(1 ) Install sprockets on huband tighten 13 screws on each sprocketsecurely.

(2 ) Position hub and sprocket assembly onshaft, line up holes, and install and tighten the 10 mountingnuts securely.

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*(3) R efer to pa ragr a ph 144J.(4) Ref er to pa ragr aph 1 4 3 &.

c. R EV E RS IN G S P RO C KE TS . Whe n th e te eth on th e sprockets bec omewor n fro m usage, th e sprockets can be reve rsed on th e hub or thec omplete hub and spro cket assem bly can be chan ged from r ig ht to lef t,

and vice versa. T hi s w ill pr esen t a new tooth su rfac e to the tra ck and p ro vid e lo n ge r life.

1 41 . Fina l Dr ive Rep face m en tA UTH ORIT Y. R epla cem ent of th is m ajo r assembly w ith a new or

re bu il t un it is nor mal ly a field m ain te na n ce o pera tion , bu t may beper form ed in a n emergency by o rgan izati onal m aint en an ce u n its , pro vided auth orit y fo r p erfo rmin g th is rep la ce m en t is o bt ai ne d from

the ap pr op ri at e commander. Tools needed for th e o pera tion w h ic h

are n ot ca rr ie d in o rga n iza tiona l m ainte nan ce un its may be obt a ine d i'rom a hig h er m ai nt en an ce un it.

&. R EM O VA L . (1) Rem ove cover pla te that pro tec ts final d rive d ra in p lu g from bottom of hul l be n eat h final drive. Remove d rain plu g .

(2) R emove fo u r screws ho ld ing ha lves of final d riv e p rop el ler sh af t g ua rd to co ntro lled d iffe rent ial a n d to final d rive case, an d remove gu ar d.

OUTER SP ROCK ET

SPROCK ET H U B^ " ~ HU B M O UN TI NG NUTS (1 0)

F ig ure 124. Removing tr ac k spro c ket.

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FINAL DRIVE MOUNTIN G SCR EWS-^ ,_15 /16" SOCKET

DO WELP IN

LOCK W IRE S-> ^ P ROCKET SHAFT-^ RAPD 331 3 36

Fi gure 128. Final drive oil vehicle.

(3) Remove lockin g wires and fou r sc rews h olding the univer sa l joint yoke on the fin al drive in put shaftto the universa l joint (fig. 114) . Comp ress the fi nal drive propel lershaft sufficiently to allo^y universal joint to c lear yoke. L ower outerend o f prope ller sha ft after tying the universal joint b earing cap s tothe cross w ith loc king wire s to prev ent acci dental disassemb ly.

(4 ) Refer to para g raph 144.(5 ) Rem ov e 10 nuts atta chi ng

hu b to shaft, and lift hub and sprockets off as an assembly.(6) Cu t locking w ire s and break

loose 18 screws (fig. 125) that hold br ac ket flange to h ull side wall.Conn ec t hoist to final dr ive sling (4 1-S-3 832-35) and in s tall on finaldrive bracket. Remove attac hin g screws, p ry fin al drive assembly offdowels, and re mo ve from vehicle (fig. 126) .

INSTALLATION . (1 ) Coat inneredges of bracket flang e w ith sealing comp ound. Raise fin al driveassembly wi th hoist and sling (41-S-3832-35) an d li ne u p dow el pins

and cap screw holes. Push th e assembly into plac e and insta ll them ounting cap screws, tightening them evenly to 170 to 180 foot-poun dsto rque. Install lo cking wires . Th en remove sling.

(2) Push fina l drive p ropeller shaft toward diff e rential and raise into po sition opp osit e yoke on fina l drive.Li ne up holes in yoke w ith holes in un iver sal join t housings an d installfou r screws h olding bearing housin gs to yoke. Tighte n screws to 130

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to 140 foot-pounds torque and in stall locking wire through each p airo f screw h eads.

(3) Position ha lves of propeller shaft guardsaround shaft and install fo ur screws holding guard to contro lled differential and final drive cover.

(4) Refer to paragraph 149&.(5) Refer to paragraph.144Z>.(6) R efer to paragraph 143.(7 ) Make sure dra in p lug and protecting plate are

reinst alled. Add engine oil to filler op ening until oil reac hes to p oflower of two filler openings. Approximately 4y 2 p ints of oil are required. Reinsta ll fi ller plug.

FINAL DRIVE SLING(41-S-3832-35)

SPROCKET SHAFTSTUDS

MOUNTINGFLANGE

Sect ion XXXII . TRA C KS AND SUSPENSION

142. Des c r i p t i o n and D ata

DESCRIPTION. (1) Two indivi du ally driven steel track s, 16inches wide, provide the nece ssary tractio n to propel the vehicl e (fig.127). Each co mple te track is composed of separate track shoes ofcast steel with c enter guides, con nected together with straight pinscarried in rub ber bushings (fig. 130). The shoes are of interlock ingdes ign to eliminate vibration and wea r that occurs when tra ck wheelspass ov er openi ngs between track shoes. Two drive sprock ets, oneon each side, pull the tracks fo rward over the supporting roller s andlay them down in the path of the advancing track wheels.

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(2) Th ere are 10 dua l tra ck wheels , 5 on each side, w hich are carried on individua l arms at tached to in dependent tor sion bars and m ountedso as to be ea s ily removable (fig . 127) . The 10 arms a re each m ountedon 2 roller bearing s carried in hou sings bol ted to th e sides of the hu ll just above the floor level. The ar ms are splined to the tor sion bar s,

w hich exten d thro ugh protective tu nnels on the hull floor. The torsio nbar s for opp osite wheels are sta ggered to per mit carr ying the w heelsat the same level. Do u ble-acting, ai rp lane-type, hydrau lic sh ock absorb er s are prov ided for the two front and two re ar su sp ension armson each side, and are mounted dire ctly on the hull s ide wa lls (fig. 12 7).

(3 ) An adjustable c ompensating wh eel for each tra c k is mount ed atthe rear of the h ull, and is conne cte d to the re ar-t rack wheel arm by alin k (fig. 136). The link is so arranged tha t any d ecreas e in tracktension caused b y lif ting of th e rear track whe els will be offset bymovemen t of th e compen sating wheel tow ard the re ar, an d a ny incre ase in track ten si on caused by dr opping o f the re ar track wheelsw ill be o ffs et by move me nt of the compe nsa ting wheel to ward thefron t.

(4) F our dual, rubber -tired track sup port rollers are m ounted oneach of the up per h ull sid es (fig. 127) to supp ort the trac k as it returnsto the dri ve sprock et.

6. DATA. (1)Numb er p er t r a c k —— —— — — — — — —— — —— _ . 80.Width___ ___ _______ ___ ___-__ 16 in ch es.Type ________ __ ________ __ __ Stee l, w ith center guide

an d rubb er bushin gs.(2)

Pitch_ ____ _____— ___ ______ _ inches.Gro u nd contact:

Zero penetration— — _—_—__— _— 122 inches.1-inc h penetration _ ___________ 126 inches.

(3)N umber (each s id e)_—__— _ _____ 5.Typ e _ _________ _ _________ _ __ Solid steel..Typ e o f springing— —— —_——— —_— _ T orsion bar .N umber o f bear i ngs-______ _ _____ 2 (stra ight-rol ler).

(4)

Numb er (each side)_ _____— ____ __ 5.Typ e _____ __ _________ _ ______ Du al , demountab le, rubber- tired .

Number b earing s (each wheel)_ ____ __ 2 (ta per, roller).(5 )

Number (each side)___ ____ ______ _ 5.Typ e _______ __ ________ __ ___ Solid steel.

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Instal latio n identification :

Left , Nos . 1 a.nd 2_ _ __________ _____ D 6 0 591BRight, Nos. and 2 ______ ____ ______ D B 0 5 9 1 A

Le ft, Nos. 3, 4, and 5_ ______ ____ ___ 7053475Rig ht, Nos . 3, 4, and 5_____ __ _______ 7053474(6)

Num ber (each si de) ________. 4.Ty pe _ ____ ______ _____ _. Dual, demo untable , rubber- tired.Beari ngs _________ __ ____. 2 (ta per, roller) .

(7)Num ber (each side) ________. 4.Ty pe ________ _ _______. H ydra ulic, airpla ne-t ype.

(8 )N u mber (each si de) ________ 5.Type __ _—____ __ _____ Vo lute spring.

1 43. Tr a c k A d j u st m e n t

G ENER AL.Caution: It is important that the tracks be pro perly adjusted to

p revent unnec ess ary wear and brea kage.P R O C E D U R E .(1 ) To check the tra ck adjustment, move vehic le to

level g round to assu re norm al track tension. Plac e a 4-foot pry b ar and imp rovised hook be tween the tr ack and suspens ion a rm ho usingat a point m idway betwe en th e second and thi rd tr ack support rollers.Pry d own with le ver so that about 20 0-pounds pres sur e is exerted a ttrack and, at the same time, la y a stra ighted ge along th e to p of the trac k between the second and third rollers and m eas ure the sag

3/4 TO 1 IN Ci STRAIGHTEDG E

THIRD T RACK R

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CLAMPBOLT

LOCK PLATE

TRACKADJ USTINGNUT

COMPENSATING AR M -' W R E N C H (41- W-1315) -* RA PD 3 31825

at this po int (fig. 128). This sag should be fr om % to 1 inch with200-pounds load applied . Track tension mu st be adjus ted to abovefigure when sag becomes 1% inches or more.

(2) If the track a djustment is incorrect, loosen clamp bolt at rear ofcomp ensa ting wheel arm (fig. 129) and slide lock plate u p fro m adjusting eye b olt sleeve nut. Tighte n or loosen adj usting sleeve n ut toobta in correct track tensio n. Tighten clamp bolt after positionin glock plate on flat of adjusting sleeve nut.

144. Track Replacemen tR E MO VA L . Install track fixtures (41-F-2997 -86) on track mid

way between compensating wheel and rea r track wheel (fig. 131) ,andtake up track tension. R e m ove track shoe pin wedge screw, lockwasher, and flat washer (f ig. 130) . Using a brass drift, drive wedgeout of block. Tighten tra ck fixtures to relieve track tension and driveout connecting pin, using knock-out pi n (41-P-560-300) (fig. 131) .Removefixtures, sta rt engines, and put trans fer unit an d transmissionshift levers in drive posi tion and run engines just fast enough to turntrack drive sprocket slowly. Then run upper half of track forwa rd offsupport rollers and drive sprockets. Tow vehicle off track. If newtrack is to be installed, place new track in front of old tra ck and towvehicleonto new track.

I N S T A L L AT I O N .Lay track out on ground and tow vehicle ontr ack so that rear end of track projects approximately 10 inches beyond rear track wheel. Pu ll front end of track up over drive sprocketand start engines, put transfer unit in reverse an d transmission in

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SHOE GUIDE

W E D G E SCREW

LOCK WASHER

,- FLAT WASHER

TRACK PIN WEDGE-

TRACK PIN

TRACK PIN BUSHING-

drive, and guide track back over support rollers and compensatingwheel as rotation of drive sprocket moves upper half of track back.Mount track connecting fixtures (41—F-2997-86) .Bring track ends

together by tightening fixture and drive in track shoe pin (fig. 1 3 2 ) .Be sure that slots in pin enter guides in pin bushing (fig. 1 3 0 ) andthat pin enters bushings without damaging bushing ends. Installtrack shoe pin wedge in hole in shoe with beveled end in, tap wedgelightly to its seat, and install flat washer, lock washer, and wedgescrew. Tighten screw to 110 foot-pounds. After run in, retightenscrew to 8 0 to 90 foot-pounds. Adjust track tension (par. 1 4 3 ) .

Caution: Be sure to install track so that grouser on block contacts

ground first as shown in figure 1.

145. Compensating Wheel, Bearings, and Seals

REMOVAL. Break track at rear of vehicle (par. 144a ) and pulltop half of track forward to clear compensating wheel. Remove 10nuts and locks holding dual compensating wheel on studs and removewheels. Remove four hub cap mounting screws, and remove hubcap and gasket. Take out cotter pin, nut, and washer holding hub on

spindle (fig. 136) . Pull out on hub enough to loosen outer bearing.Remove outer bearing. Lift off hub and inner bearing. Pry greaseseal off spindle bearing spacer with screw driver.

& . INSTALLATION.Place new oil seal on spindle with feather edgetoward arm and, using oil seal replacer (41-R-2383-950), tap overbearing spacer until seal contacts spacer (fig. 140). Place wheel hubon bench with wheel side down and pry grease retainer out of hub.

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R E A R TRACK W H E E L CO MP E NS ATING W H E E L

BLO CKP IIDR IF T P IN (4I-F -29 97-8 6)(41 -P -560 -3 00 )

R A P D 33 13 40

TR ACK C O N NE CT ING P IN -, .- TRACK WHEE L / -C O M P E N S A T IN G WHEEL

P IN WEDGE SLOT _ / TR ACK F I X T U R E (41-F-2997-86J-V

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W HEEL(S C R E WL O C KIW A S H E RN U T

DIR T S H E D D E R -

IN N E R C O N E

£-HUB C A P

K E Y E D WA S H E R

O U T E R C ON E

O IL S E A L

B E A R IN G S PA C E R -

S E A L S PA C E R -

H UB A S S E M B LY

W HE E L. A S S E M B L Y RAPD 331375 .

Place new g re ase reta in er in repla cer (41-R-2 39 0-450 ) (fig. 134)and posit ion replace r on hub . Dri ve reta iner carefull y in to p osition (fig. 135) to pre ven t coc k ing in hub and remo ve to o l. C heck re taine r to see th at it is square in the hu b count erb ore a n d that thefl ange of retaine r is tr ue . G reas e inn er roll er b ea ring assembly thor ough ly w ith lubr ic ant and pu sh on spin dle shoulde r u ntil be ari ngcontact s sp acer. Pus h h u b asse mbly on spindle, makin g sure inn e r

bear ing enter s rac e in h ub. F ill outer roller be ari ng w ith grea se and install on spindl e , holdin g wheel h ub cente red on spindle an d pu shi ngouter be aring into race . Insta ll keyed w asher o n sp indl e and se at onbearin g. Ins tall nut on spindle.

ADJUSTMENT. Rot ate h ub and , at the sa me tim e , tighten nut to200 foot- poun ds torque. B ack off n ut unt il th ere is no tor que, the n retigh ten nut to 75 foo t-po unds torqu e. Ba ck off nu t to first co tterp in hole wit h m inim um trave l of 15° and inst all cotte r pin. I f firsth

ole is less tha n 15° tra vel , bac k off nu t to nex t hold o r 30° mo re.P osi tion h ub cap and insta ll f our m oun ting screws. Using pr essure g un, fo rce m ore greas e into h ub until it start s com ing ou t of g reaseshiel d at rea r. Wipe off all excess grease. L ift wheels an d installon hub studs, th e firs t wheel w ith concave sid e in, the second w ithco ncave sid e ou t. Insta ll 10 nuts w ith locks a nd tigh te n eve nl y with250 to 300 fo o t-pound s . Inst a ll a nd adjust t rac k (pa rs. 144& and1436) .

146 . C o mp e n s a t in g A rm an d LeverREMOVAL. R emove compen sa ting w heel and hub as p revious ly

o u tlined in parag ra ph 145a. Re mov e cotter p in, nut, and wash e r fr omcom pens atin g lin k b olt at rear end of link. Ins tall slid e ham m erada pt er (4 1-A -18-2 45 ) on link bo lt head, being su re that stud isscrewed a ll the w ay i n bo lt and h exagon shou lder of adap ter seats on

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bolt head. Attach slide hammer puller (41- P-2957-33) and pull bolt(fig. 137). Push link end dow n and out of compensating lever. Ifnecess ary, hook hoist on rear suspens ion wheel and raise wheel. Thiswill move link end to rear of vehicle so that drift and hamm er can beu sed to drive out bo lt. Remove six attaching screws and remo ve compensating arm cov er (fig. 136) ; then discard gasket. Remov e lockring holding arm and lever on compensating wheel spindle and lifts uppo rt arm and lever off spindle as an assembly. Remove screwsholding spind le to tapping pl ate on hull an d rem ove spindle.

INSTALLATION. C o at flange of spindle with se alin g compound and position spin dle on hull tap ping plate, and install eight moun tingscrews dipped in seal er. T ighten screws to 240 to 260 foot- pounds,us ing to rque wrench. Install arm and lever assembly on spindle, see ingthat shoulders on spind le enter bearing races and that gre ase sea l slipsover beari ng spacer. Install sna p ring on spindle end to hold assem bly.Using new gasket, positi on compensating a rm cove r and install sixattaching screws. Connect compensating link to lever (fig. 136) anddrive in bolt, using a sof t hamme r; then install washer, nu t, and cotterpin. Tighten washer and nut on connecting bolt to 180 foot-poun dsminimu m. Install compensating wheel and hub (par. 1456) andadjust (par. 145c).

COMPENSATING A RM B E AK T N OREPL ACE MEN T. (1)

Refer to above.

GREASE RETAINER REPLACER(41-R-2390-450) GREASE RETAINER

TRACK WHEELHU B

IN N E R B E A R I N GC U P

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(2) Rem ove lever clamp ing bolt, lock pla te, andwasher (fig. 130). Remove adj usting sleeve nu t and thrust wa sher.Rem ove lever with adju sting ey e bolt fr om supp ort arm body. T apinner roller bea ring and greas e retainer out of wheel s upport arm.Tap ou t the outer ball be a ring.

(3) Grease be arings thoroughl y with specified lubricant. Rein stall bearin gs in support by tapp ing in u ntil they seaton shoulders in arm, using a block of wood or a brass drift. Placenew grease seal in in ner side of a rm with feathered ge toward vehiclea nd tap in un til it seats on shou lder of arm. In sta ll adjustin g eyebolt in le ver, and place ad justing sleeve nu t (thoroughly g reased withlubri c ant) and thrust washer on ey e bolt. Install leve r with eye b oltand nut on ar m. Install lock plate and lock w asher on clamp b olt and

turn bolt into lever.(4) R efer to & above.

147. C o m p e n s at i n g L i n kR E M O VAL . Remove com pensating wheel and hub (par . 14 5a).

Rem ove nut, cotter p in , and washe r from ins ide end o f com pensatingli nk rear bolt. Inst all adapter (41-A -18-245) on link bolt, atta c hsli de hammer (41-P-2957-33) to adapter, an d p ull bolt (fig. 13?).

Work ing a t fron t en d of com pensating link, rem ove bo lt holdin g li nkto rear suspen sion arm in sa m e ma nner, and remove link.

'

J J ->

GREASE R ETAINER REPLAC ER(41-R-2390-45 0)

T R A C KWH E E L H U B — ' l| ^^ |

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I N S TA L L AT I O N .Li ft compensating link into posi tion on rearsuspensio n arm (fig. 136) and line up connecting bo lt holes. Placeco mpensating link bolt in positio n and drive in , using a soft-face dhammer. Insta ll washer an d nu t on bolt and tig hten to 180 footpo unds minimum. Connectrear end of link to compensating arm in the same manner. Install compensating wheel and hub (par. 1456)and adjust (par. 145c). Connect tr ack and adjust (pars. 1446 and 1436) .

148. Track W he e l s , Bea r i n g s , and SealsR E M O VA L .(1 ) If wheel lifter (41 -L-1400) is

available, proceed as follows: Loosentrack adjusti ng sleevenut severalturns to relieve track tension. Pl ace wheel l ift blockover track guidesbetweendrive sp rocket an d N o. 1 track wheel. D rive vehicle forwardslowly unt il wheel to be removed rests on center of block (fig. 138) .Plac e suspension arm hook under suspension arm and over top of

A-SHOCK ABSORBERS B-WHEEL H UBC-CUSHIO N STOPD-SUSPEN SION ARME-COMPENS ATION LINK BOLT F-TO RSION BAR RETA INING NUT

G-COMPENSATING LINKH-COMPENS ATING W H E E L

SPINDLE

J -CO MPENSATING ARMC O V E R

K-COMPENSATING LEVERL-A DJ USTING EY E BOLTM-SLEEVE NUT LOC K PLATEN-LEVER C L A M P BOLTO-ADJ USTING SLEEVE NUT

R A P D 331948

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SLIDE HAMMER P U L L E R(41-P -2957-33) ^ OMPENSATING LINK

cushion stop bracket, making sure that top of hook is between springmounting screw and bracket mounting screws (fig. 1 3 8 ) . Drive

vehicle slowly either forward or backward until track wheel next tothe one to be removed rests on top of the wheel lifting block. Setbrakes and stop engines. Removo 10 nuts holding wheels to hub andlift off wheel. If wheel lifter (41-L-1400) is not available, set brakesand place a block of wood (2 by 4 inches or 2 by 6 inches) againstinside edge of track. Position hydraulic jack with base of jack ontrack and block of wood under suspension arm to be lifted (fig. 1 3 9 ) .Lift suspension arm until wheel clears track guides. Remove 10 nuts

holding dual wheels to hub and lift off wheels.Caution: Exercise care in lifting arm to prevent arm end from slipping off jack as a lift of approximately 9,000pounds is required to raisearm sufficiently to remove wheels.

(2) Remove four hub cap mounting screws(fig. 133), remove cap, and discard gasket. Remove cotter pin, nut,and keyed washer that hold hub assembly on spindle. Pull hub outenough to move outer roller bearing out of cup in hub, and removebearing. Pull hub assembly off spindle, and remove inner bearing.

(3) Pry oil seal off bearing spacer on spindle(fig. 133) and discard.

Exercise care in prying off seal, or dirt shedder in back of seal will bedamaged necessitating installation of new shedder.

Place hub assembly on bench with wheel side down and pry outgrease retainer (fig. 134).

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C U S H IO N STOP BRACKET

TRACK WHEEL (RAISED)

LIF T IN G BLOCK -JBE

L if ti n g T r a c k W h e e l

C U S H IO N STOPM O U N T IN G

SCREW

WHEELM O U N T IN G

NUTS

T R A C K WHEEL(READY FOR

R E M O VA L)

S US P ENSION A R M H O O K

S US PENS ION A R M H O O K

LIF T IN G BLOCK

T r a c k W h e e l o n H o o k

C U S H IO N STOPM O U N T IN G t

,

SCREW

S USP ENSION A R M

T R A C K WHEEL HUB

SUSPENSION A R M H O O K

LIF T IN G BLOCK

T r a c k W h e e l R e m o v e d

2 4 4

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(4) Drive be aring races out of hub carefully, using a brass drift an d a ham mer.

INSTA LLAT I O N . (1) Drive beari ng racesinto wheel h u b, using a brass d rift or block of wood and be ing carefulto preve nt coc king of race in h ub.

(2) Place ne w oil se a l over spindle with fea ther-edge o f seal towar d ar m and, using oil seal replacer (4 1 -R-2383-950),drive seal into po sitio n on bearing sp ac er (fig. 140). Place newgrease retain er in replacer (4 1-R-2390 -450) (fig. 134), and p ositionreplacer on hu b. Drive retain er into p osition (fig. 135) c arefu lly toprevent co cking in hu b, and rem ove tool. Chec k retainer to see thatit is square in hu b count erbore an d tha t the flange in retainer is tr ue.

(3) Pa ck inner roller b earing th orough ly withspecified grease an d push on spind le and over sho u lder. Lift hub assembly onto spindl e and ove r inner bearin g. Pack outer bea ringw ith grease and pus h on sp indle and in to race in hub, centering hubon spindl e. Install keyed wa sher and bearing retainin g nut. Adjust wheel bearing (par . 145c). Place hub cap on hub using new ga ske t,.and ins tall fou r mounting screws. Connect lub ri cating gun to f ittingon hub and force grease into hub until excess grea se comes out in b ackof h ub . Wipe off all excess grease.

(4) P ositio n dual track wh eels on hub. In stall 10mounting nut s and tig hten to 250 to 300 fo otpounds. If wheel li ft

HYDRAULIC J ACK —. — S U S P E N SION AR M

- W O OD B L O C K S R A P D

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was used for removing wheels, drive vehicle forward or backwardslowly until track wheel lifting block is under wheel supported bysuspension arm hook. Remove hook from suspension arm and cushionstop bracket. Drive vehicle in reverse slowly until-lifting block isbetween drive sprocket and N o. 1 wheel. Remove lifting block. Adjust the track (par. 1436). If wheel lift was not available and wheelswere removed by using- a hydraulic jack, position wheels on hub, install mounting nuts, and tighten to 250 to 3 00 foot-pounds. Lowertrack wheels to track and remove hydraulic jack and blocking.

149. Torsion Bars

R E M O VA L .(1) Disconnect shockabsorber at lower end (par. 152a).

(2) Place hydraulic jack under vehicle sothat base of jack rests on track and block of wood and top of jack isunder suspension arm. Raise arm high enough to remove the wheel.After wheels are removed, lower jack until all tension is removed fromtorsion bar.

(3) Remove screw that holds torsion bar tobar retaining nut. Remove bar retaining nut. Screw adapter (41-A-18-245) for slide hammer into torsion bar, being sure that stud isscrewed all the way in bolt and hexagon shoulder of adapter seats onbolt head. Attach slide hammer puller (41-R-2957-33) to adapter,and pull shaft out of suspension arm (fig. 141).

INSTALLATION. (1) The suspensionarm torsion bars have designating arrows stamped on the arm end.The arrows indicate the rotation of the bars when the wheel and armare raised, or in other words, the direction of bar "spring." The twofront wheel bars on the right-hand side of the vehicle have designatingarrows in clockwise rotation. The two front wheel bars on the left-

hand side of the vehicle have arrows pointing in the counterclockwiserotation. The three rear suspension arm torsion bar on the right-handside of vehicle have an arrow indicating counterclockwise, and thethree rear arm torsion bars on the left-hand side of the vehicle haveclockwise arrows. Be sure to install torsion bars in the correct locations. The two front bars on each side are smaller diameter bars andmust be reinstalled in this position.

(2) The suspension arm torsion bars havedesignating arrows and part numbers stamped on arm end. The arrows indicate the rotation of the bars when the wheel and arm areraised. Slide the correct torsion bar into the tunnel until the innerend of the bar contacts the anchor. S ee paragraph 142 for torsion baridentification and position. Examine the outer end of the torsion barand rotate it until the small slot that is cut in the chamfer is straightup (vertical). This will also insure a vertical blind spline at the

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anchor end of th e ba r; a re qui rement for proper entr y o f the ba r intoits anc hor. Gentl y tap the b ar in to the anch or w ith a soft-fa cedhamm er. I f the bar will no t e nter read ily, loosen the cap sc rew s ho lding th e anc hor s uppor ting plate a little more and make c ertain tha tthe four cap scr ews are loose ned approxim ately the same amoun t.

Th e two cap screws hol di ng the anch or to the su pp orting p late do nothave, to be loosened. A fter th e torsion ba r has ent er ed the an chor,rais e the suspen sion arm u ntil th e sma ll slot cut in the outer edge ofth e arm lin es up with the blind splin e in the outer end o f the torsio nba r. The torsion bar can the n be tapped all the wa y into place . In st all th e tor sion b ar re taining nu t and tight en to 75 fo o t-pounds. Install the ca p sc re w in the re taining nu t and tight e n it to 65 footpou nds. Tigh te n the to rsion b ar anchor plate screws to 35 fo otp ound s.

(3) Position hy draulic ja ck an d block o f woodu nd er suspe nsion arm on track edge, and raise ar m until w heel can be ins talle d. Positio n dual tra c k wheel on hub studs and insta ll ten wheel mounti ng nut s. Tigh ten n uts to 250 to 300 fo ot -pounds.Lowe r wh eel to track a nd re mov e ja ck an d b lockin g.

(4 ) Conne ct sho ck ab sorber lowe r end tosuspen sion arm (par. 1526).

1 50.S u s p e n s i o n

A r m

REMOVAL. Remov e trac k wheel and torsi on bar (pa r. 149a).Rem ove seven screw s th at hold suspension a rm assem b ly to hul l s ideand lift o r hoist ar m out of hull opening .

INSTALLATION. Co at susp ension arm m ounting plate flange onh ull with joint a n d thread compou nd ( cement, typ e II). Lif t or hoist a rm assembly into posit io n on hull s ide and line up mount ing ..crewholes with a drif t p unch. D ip seven a rm-mount in g screws in jointa nd th read compoun d, ins tall in arm flang e, an d tight en to 240 to 260 foot-pou nds . Insta l l torsio n b ar and trac k wheel (p a r. 149d).

151. Track Su p por t R o l le r s , B ear ings , and S eals

RO LLER RE MO VA L . Pla ce bl ock o f wood on track wheel ne arestroll er to be rem ove d. S et jack on wood bl ock and raise tr a ck untilit c lears roller (fig. 142). Remo ve five screws th at hold rolle r mounting bracke t to hull sid e wall, and remove rolle r .

Z > . TRACK S UPPORT ROLLERINSTALLATIO N. Coat fl ang e of ro llermounting bracket w ith joint an d thr ead co mpound (ce m ent, type II) .Lift sup port roller assem bly up unt il track gui des e nte r spac e betw ee nroll ers, and po sition mou nting bra ck et on hull side w all. Line upmoun ti ng screw ho les in brack et flange and hull side w all. Dip m ou nting scre ws in joint and thre ad com pound and install, dr awing upeve nly.

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ROLLER M OUNTIN G T R A C KB R A CK ET __. ,- TR AC K S U P P O RT ROL L E R

ROL L E R MOU NTING SCREWS H Y D R A ULI C J A C K • -W OOD B L O C K

c. BEARING A N DSE AL EEPLA C E M E N T. (1 ) Kemove tracksupport roller as outlined in above. Remove fou r screws that ho ldhub cap to wheel hub, re move cap , and discard gasket. Rem ov e cotterp in an d nut that hold bearings on ro ller spind le. P ull out on roll er

to move out er b earing and keyed washer out of roller hub. Removeouter b eari ng and wash er . Lift roller and hub asse mbly off mounting b racke t spin dle. Remove inner bearing and gre ase retain er. Pr ygreas e seal off be aring .spacer and discard.

R emove grease seal carefu lly to prevent dam age to dust she dd er.

Remove bear ing race s from hub, us ing puller (41- P-2905-60).(2 ) Install bearing races in roller h ub by dri ving

c arefully into place with b rass dr ift or blo ck of wood unt il they seat

in should ers of hub. Plac e new grease seal on suppo rt spi n dle wit hfeat heredge tow a rd m ounting b racket and drive into po sition on b ear ing spacer, using seal replacer (41-R-2 397-875) (fig. 144). Place new grease re tainer in pos ition on re placed (41-R-239 6-375) w ith flan gededge a gain st shoulder of to ol, an d drive i nto support roller (fig. 143),u ntil it sea ts on hu b sho ulder. Pack inn er bearing with specified grease and pos ition on spindle. Install rolle r and hub ass embly on

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sp indle and over grease seal an d inner bea rin g, b eing careful to p re ventbuck lin g grease seal leathe r. Pa ck outer bearing wi th specified grease,an d ins tall on spindle a n d into race in hub. In stall keyed wash er an dn ut on spindle, and tig h ten adjus tin g nu t to 150 foot- po unds torque.Back off nu t u ntil th er e is no torque. Retigh ten nut to 75-foot-pounds

torque. Back off nut to fir s t cotter p in hole wit h minimum trav elo f 15° an d install co tter pin . I f first hole is less than 15° travel, backoff to ne xt hole or 30° more. Usi ng new gasket, pos ition hu b cap andins tall four screws. In st all support ro ller assembly (6 abo ve).

152. S h o c k A b sorbe r sR E MOVA L . W orkin g at u pper end of shock absorber, remove cot

ter pin , nut, and w ashe r that hold end of shock absorber to m oun ting

br ack et on hu ll side. Screw pulle r (41-P- 2907 -196) on bu shing flangeof shock absorber. Hol d body of pu lle r wi th la rge crescent wrench a nd turn down puller bolt, pullin g shock ab sorbe r off p in (fig. 145).Worki ng at lower end of shock absorber, remove cotte r pin, n ut, andw asher that h old .shock absor ber to moun ting pin on suspension arm.Usin g puller (A7079316), remove lower end of shock absorber from mou nting pin in same m an ner.

Use of a longer %16NF 2-bolt in shock puller will permit pulling lowerc-ndof shock ab sorb er completely off pin.

G R E AS E RETAIN E R

R E P LA C E R(4I-R-2396-3 75)

T R A C K S U P P OR TR O L L E R

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INSTALLATION. Lif t shoc k absor ber i nto posi tion , and enter upperend bearing ov er mo unting bracke t p in. D rive bearin g int o po sitionon mounting b racket car efully with a soft-fa ced hamm e r, instal lwashe r and nut, and tighten nut to 180 foo t-pound s, u si ng a torq uewrench . Inst all co tter p in. M ount lower end of shock absorber on p inin su sp ension

arm in the sam e manner .1 53. Su s pens ion Arm Cush ion Stop

a. RE M O VA L . Kemove bo lt and spac ing w ashe r that hold volutesp ring in stop br a cket and remove spri n g. Remo ve two bolt s insideof sto p bracket that hold assembly to hull side w all. Rem ove twomountin g bolts that hol d upp er end of stop bra cket on hu ll s ide (fig.1 36), an d rem ove stop b racket.

6. IN STAL L ATIO N . Iden tify proper cush ion stop b ra cket for rightand lef t sides. Wh en b racket is proper ly installed, th e boss on thebottom of the brac k et should point forw ard to ward the wheel andinstall tw o upper screws and washer. T hreads of sc rews shou ld bewell co ated wi th sealing com po und bef ore ins tall ation. Wo rkingunder s top b racket , install tw o lo wer m ounti ng scr ews and w asher.Tig hte n the fou r attaching screws to 80 to 85 foo t-pound s to rque.

Sect ion X XXIII. HUL L

15 4 . Descr ip t ion and D ata

a. D E S C R IPTION. (1 ) The hull of th e vehicle is a com ple tely we lded s truct ure except for port ion s o f the f ront, top, an d floor, w h ich areremo v able for se rv ice o pera tions. The se remov ab le po rtions consistof a plate above the con trolled diffe rential at t he fr ont of th e vehicle ,two d rivers' door s over the d riv ers' seat s, a hinged a ir outlet d oor o verth e engine co m partment , an air inle t grille ove r the rad ia tor comp art

m ent, tw o st ow age com par tment d oors at rea r and rem o vable cover s (on each sid e ) over eac h fuel tank and over each batter y . Open ing sin the b ottom of th e hu ll inclu de the two large i nspe ction pl ate s, oneu n der each en gine and transm issio n; and the small covers just bene a ththe drain p lugs for th e engin es, h ydramatic transmiss ions, trans ferunit , controlled differentia l, an d final drives.

(2) T he hul l floor carri es the moun ti ng brac ke ts for the engine andtran smissio n sup ports , t he transf er un it su p ports and the different ia l

suppor ts. It also incorporat es the tunn els in whic h the torsio n b arsfor th e track susp ension wheels are carri ed. The h ull is d ivid ed in tothr ee compa rt ments: The drivin g co mp artment at the front , an engin e compar tm ent at th e cent er, and the stowa ge com par tment and gu nmoun t platform at the rear. The two front comp artments a re se para ted by a bu lkhead that ex tends fr om side-to -side and f ro m the roof d o wn to the- bulkhea d extensions , wh ich in tu rn exten d for ward to

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cover the transfer unit. Another bulkhead separates the engine andstowage compartments. The front of the hull slopes downward at thetop and upward at the bottom to form a V. The sides of the hull slopeinward at the bottom.

(3) Seats for the driver and assistant driver are mounted in the

front of the hull. These seats have both an up-and-down and fore-and-aft adjustment (par. 11). Protective pads for driver andassistant driver are provided around the final drive propeller shafts,at the sides of the controlled differential and on the periscope headrests.

(4) The various stowage items carried in the hull are mounted insheet metal containers which are bolted or latched to the hull floorand side walls. Ammunition stowage is provided in tubes under thegun mount platform, and in ammunition

boxescarried on

floorin

rear compartment.D ATA . For detailed data on the hull refer to paragraph

155. Seal ing Hul l PartsGENERAL.Joint-sealing compound should be applied to detach

able hull parts when they are assembled to the vehicle to preventwater, dust, or fine sand from seeping through the joints and enteringthe hull.

PARTS To BE SEALED. (1) Differential opening cover.(2) Final drive housings.

R E P L A C E R(41-R -2397-875)

OIL S E A L

DUST SHEDDER

SUPPORT ROLLERM O U N T I N GBRACKET

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HANDLING. (1) Any cylinder containing gas under high pressure is as dangerous as a loaded shell. The extinguisher cylindersshould never be dropped, stuck, handled roughly, or exposed to unnecessary heat.

(2) Red safety blow-off seal on valve head indicates whether cylinder has been discharged due to high temperature. Seal should beexamined regularly; if it is missing, the cylinder should be replaced.

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PART FOURAUXILIARYEQUIPMENT

Sect io n XXXV. GENERAL168. Scop e

Part Four contai ns information for the guidance o f personnel responsi ble for operation of this equipment. It conta ins only th e informa tion necessary to using personnel to properly identify, connect, andprotect such a uxilia ry equipment while b eing us ed or transported withth e main equipment. Detailed in structions on this equipme nt ar econtained in separate technical m anuals.

Sec t ion XXXVI. ARMAMENT

169. ScopeSection VII contains infor matio n required by the usi ng a rms to identify and operate the 155-mm. howitzer M l in the 155-mm. howitzermoun t M 1 4 . For preventive maintenance, malfunctions and corrections, disassembl y, assembly, and general mainten ance of the 155-mm.howit zer, refer to TM 9-331 . For lu brication instru ctions, refer tosection XIII of this manual.

1 70.Charac t e r i st i csThe armamen t of the 155-mm. howitzer motor carriage M 41 is

emplo yed ag ainst emplaced battery and other ground obje ctives. The155-mm. h owitzer m ount M 14 for the weap on is loca ted in the fighting compartment at the rear of the howitzer motor carr iage (figs. 1, 2,150, and 151).

The 155-mm. howitzer Ml is a medium-barre led weapon usingseparate-loading a mmunitio n. It is eq uipped with a manu ally operate d breech mechanism and a perc ussion-type firing me chanism.The howitzer has a range mo vement in elevation of — 5° to +45° and atra verse range of 37°, right 20°, and left 17°. It is equipped with recoil mechanism M 6 B 1of the var iable recoil, hydr opneumatic typ e .The length of rec oil varies from 60 inches at 0° to 25° elevation to 41inches at 40° to 65° elevation. Elevation an d depression of the muzzle-heavy w eapon is assisted by sp ring-type e quil ibrators.

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173. Inspection Before Firing

Prior to firing, inspect the bore and breech to see that no dirt orforeign matter has accumulated. If there is foreign matter in thebore, clean the bore thoroughly and wipe it dry. Normally, the boreshould be wiped or cleaned with rifle bore cleaner to remove the coating applied after the previous firing.

B R E E C H O P E R AT I N GLEVER CLOSING1 AT C H

FIRING MECHANISM Ml R E M O V E DFRO-

FIRING MECHANISM HOUSING

RA PO 63218

B R E E C H B L O C KR O TAT I N GC A M

B R E E C H B L O C KDRIVERROLLER

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Check the replenisher and recuperator to make certain that thereis sufficient oil in the recoil and recuperator cylinders. Eefer toTM 9 -331 .

Inspect to see that there is no leakage of oil, that the bearingsurface of the howitzer tube is well lubricated, and that the piston rod

nuts are properly tightened.For bore-sighting weapon, refer to paragraph 182.

174. To Traverse

The traversing handwheel is located on the left side of the carriage,ahead of the elevating handwheel (fig. 156). One complete turn of

I N T E R R U P T E D T H R E A D SON B R E E C H B L O C K

I N T E R R U P T E DT H R E A D SIN B R E E C H RING

the handwheel in a clockwise direction traverses the carriage to theright approximately 10.3 mils (34.7minutes). The range of traverseis 3 7° or 17° to the left and 20° to the right of midposition. Approximately 64 turns of the handwheel are required to traverse the mountfrom one side to the other of its range of traverse.

175. To Elevate

The elevating handwheel is located at the left rear of the carriage inback of the traversing handwheel (fig. 156). One complete turn ofthe handwheel in a clockwise direction elevates the weapon approximately 10 mils (3 3 minutes). The range of elevation is 1,156 mils(65°). Approximately 78 turns of the handwheel are required toelevate the weapon from 0° to 65°.

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(8 ) Place the charge in the chamber withthe igniter end to the rear, and push it in until the base of the chargeis flush with the rear end of the chamber. The igniter pad must comedirectly in front of th e vent when the breechis closed to insure ignitionof the charge.

T o insure intransmission of the flash from the primer to the charge,the obturator spindlehead should come in contact with the base of the charge whenthe breech is closed, must push the charge forward to its final position, and mustremain in contact with it .

T o C L O S EBREECH. Swing the operating handle lever in a horizontal arc to the left. W h e n the breechblock driver roller enters thebreechblock rotating cam, raise the operating handle lever upwardand forward until the operating handle latch latches the lever.

RA PD J 3277I

177. To FireInsert a percussion-type primer in the firing mechanism, Ml

(fig. 157). T he primer case is inserted into the primer holder bypressing the head of the case downward firmly against the firing pinguide so that the rim. of the case slides under the edges of the slot inthe primer holder. The primer is then held in position by the pressureof the firing spring.

In inserting the primer in the primer holder, the primer shouldbe held in such a manner that no part of the hand is in front of thewad end of the primer. This precaution must be taken to avoid asevere burn in the case of premature discharge of th e primer.

Should the primer be slightly oversize or the primer holderdirty, the primer will stick before it is properly seated. Force shouldnot be exerted. Remove the primer and clean the primer holder, orinsert another primer.

Insert the firing mechanism in the firing mechanism housing,taking care that the front end of the primer has entered th e obturatorspindle plug. Seat the mechanism by turning the firing mechanism

752022 O—17———18 269

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Th is opera tion is permissible in indi rect fire.) Th e h owi tzer is nowla id in elevation. W hen a hi gher degree of accuracy is requ ire d, con tinue the o peratio n by pla c ing an accur ately set gunn er's qua dra nt on the quadra n t seat an d ro tatin g th e ho witze r e lev ating hand wh eel to cente r th e level bubble in the quad ran t.

To aim the howi tze r for dire ct fire, proceed as follo w s: Set th eelevation knob on the pano ram ic telescope to zero elevati on by m atc hing th e coarse zero gradu ation an d t he m icromete r zero gr aduation agai nst t he ir indexes. S et th e azi mut h scale, micr o meter index, and

.I Jfl fiff

RA PD 102 864

i

micro m eter to zero. S et th e elevation scale and m icrome ter on th etelescope m ount to zero. C ross-level the mou nt an d keep it cross-leveled du rin g the re m aining o peratio ns. Usin g th e how itzer tr a versing and ele vating handwheels, b rin g the ta rget to th e requir ed rang e and deflection on th e telescope reticle.

1 82. B o r e Sighting

The p urpose o f th e bor e-s ightin g ope rat ion is to te st the aline-m ent of th e sigh tin g equipment for pa rallelis m with the bore of th ehowitzer. For expediency, it may be perfo rmed by sightin g on awell-defined object at least 1,500 ya rd s dista n t.

Open the breech o f t he howitzer, place bore sigh ts in the tube,and , while looking through th e tube, aline th e howi tz er on the dista ntobject. With the telescope in position in the mount (az imuth scalese t at zero), observe th rou gh th e eyepiece and note the po sition of the cross lines w ith respect to the d istant object or aiming po int. If they do n ot coincide with the distan t object or aimin g poi nt, move the lineof s ight, as follows : Loosen the headless lock screws in th e telescopesocket and ad just th e tangen t screws u ntil coincidence is o bta ined; tighten th e headless lock screws.

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BODY S P R I N G ECCENTRICA S S E M B LY- ,

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w ith S below it, and time gradua tions to 75 seconds with 0.5-secondintervals, are stamp ed on the body. The gradu ations run cou nterclockwise, view ed f rom the point of the fu ze. Two setting grooves,one each on the lower cap a nd body, are provided for setting the fuze.A safety feature incorpo rated in the fuze is designed to p rev ent functioning sho ul d the fuze be set for 3 seconds or less. As shipped, thefuze is set "safe. " T hat is, the set line in the lower cap is in alinem ent

with the safety line S in the body. A pull wire is fitted to the fuzeto secure the f irin g pin prior to firing. A cotter p in with pull ring isas se mbled to the boos ter to preven t accidental movement of thedetonator d uri ng shipment. The boos ter is assembled to the fuze atthe time of manu facture and ha ndle d thereafter as a single unit withthe fuze, in shipment and ass embly to the projec tile. The cot te r pinis to be withdr awn just pri or to assembling the fuze with b ooster tothe shell.

(2 ) T o fuze the projectile proceed asfollows:Remove the eye bolt lifting plug from the pro jectile.

(& ) Inspect the fuze c avity and threads. They should be free offoreign matt er which would interfere with the proper assembly of thefuze.

Rem ove the c ot ter pin from the boost er.Screw th e fuze with boos ter into the projectile by hand.

Tig htenwi

th thefuze wrench.

Remove the safety pull wire. This can be d one re adily by pulling the end of the wire from the hole in the low er cap and s lidingthe wire off the end of the fuz e.

(/) Set fuze by mean s of fuz e setter, the lower cap bei ng turned ina counterclockwi se direction as v iewed from the point of the fuz e.T he torque required to set the fuze is between 80 and 100 inc h-poun ds.

CP FUZE M 78 (T105 ). (1 ) T he M 78 (T10 5)

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con crete-piercing fuze and M 25 (Tl El) booster (fig. 176) are used to convert the HE shell M 1 0 1 or M k3Al into a concrete-p iercing shell.In this case, both the fuze and booster are shipped in the same contain er, but as se parate components. The fuze is a solid hardenedsteel nose plug which contains a detonator assembly in its base. It is

shorter and heavier than the fuzes described above. The fuze M 78is fitt ed w ith either a 0.025-secondde lay or nondelay eleme nt; theam ount of delay is as indicated by th e stamp ing on the body of the fuze.

All fuzes T105 were equ ipped w ith 0.05-second delay detonator assemblies during the ea rly deve lopment of this fuze.

Nondelay fuzes are designed primarily for sp otting purposes.Fuzes w ith 0.025-second delay elements are designed to be used forfiri ng for effect. The booste r M 25 (TlEl) is a modified M2 1 A 2 booster con taining approximately three exte rnal threa ds rather thansix. A co tter pin with pu ll rin g, which is located in the booster body,must be removed prior to assemblyof the booster to the shell. Thisbo oster is intended for use only with CP fuze, M 78 (T10 5).

(2 ) After removal of lift ing plug fromprojectile, proceed as follo ws:

Remove the safety pin fro m the M 25 booster and screw thebooster into the booster cavity in the shell. Tighten booster fi rmly

with the boos ter end of the wrench (fig. 177) which is issued wit h theM 78 fuzes.

FUZE END

BO O STER END-

RA PD 26820

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RA

P

6

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(&) Screw th e M 78 fuze into th e fuze cavity and tighten securelywith fuze end of wrench. B e sure th at the fuze shoulder seats firmlyagainst the nose of th e shell ; th ere should be no space betweenshoulder of fuze and shell. D o not stake fuze to the shell .

187 . Su bca l ibe r A m m uni t i onThe roun ds listed below and illustrated in figure 178 are auth orizedfor use for subcaliber purposes.

SHELL , fixed, p ractice , M 63 M od 1, fo r 37-mm subcalib er guns,M 1 2, M 1 3, M 1 4 , M 1 6 ,and M 1 9 1 6.

S HEL L, fixed, pr actice, M92, for 37-mm subcaliber guns, M 1 2 ,M 13, M 14, M 1 6 , an d M1917 .

Sect ion XL . RADIO A N D INTERPHO NE EQUIPMENT

1 8 8 . Radio an d In terp h o n e Equ ipmen t

G E N E R A L .H owitzer motor carriage M 41 (155-mm. howitzer) isequipped with rad io sets SCR-610 or SCR-619 and interphone equipm ent RC-99. T hese radio sets and the interphone equipment opera teoff of the 24-volt ve hicular e lectrical system, except for the S C R-610when equipp ed with power u nit PE-117. Th e power connections fo rthe interphone eq uipment are made in the rad io ter minal box moun tedin the hull ceiling. R adio sets S C R - 610 and SCR-619 ar e frequencymodulated and voice-operated only. Signa l Corps drawing and inst allation instructions have been prepared for radio and in terphonein stallation s referred to above. If needed, copies may be obtain edthrough or ganization al sign al officer.

R A D I OS E T SCR- 61 0 (figs. 179 an d 180). Major components ofthis set consist of a ra dio receiver and transmitter BC-659 and platesupply unit P E-1 17 or PE-120 mounted on moun ting base FT-250 .

R A D IO S E T S C R - 6 1 9 (figs. 181 and 182). M aj or components ofthis set consist of a radio receiver and transmit ter BC-1335 ,battery charg er PE-2 19 an d battery boxes C H -291 moun ted on mounting baseFT-5 06.

I N T ER P H O N EE Q U I P ME N TR C - 9 9 . C omponents of this equipmentare interp h one amplifier BC-667 (figs. 183 an d 184) an d co ntrol boxesB C - 6 0 6 and BC - 7 3 9 (figs. 185 and 186). In terphone ampli fier is

located on vehicle front plate d irectly in front of -co-driver. C ontrolboxes are pro vided for th e driv er, assis tant driver, gunner , andcom m ander.

189. Mo untin gs

M O UN T I N G B A S EFT- 2 50 (fig. 180). This mountin g base is usedw ith rad io set SCR-61 0 described in par agraph 188. B ase is made

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u p o f tw o sections w hic h a re connected tog eth e r thr o ugh fou r rub bergrommets. Lo w er section is fast ened to vehicle br acket s with fou rcap screws. Pl at e su ppl y un it fas tens to to p po rtion of mo unti ng base by use of fo ur sn ap fa sten ers. T ran smi tte r-r ec eiv e r is located on to p of p late sup pl y un it a n d is faste n ed th ereo n by use of sn ap fa sten ers.

&. M OUN T ING BA SE FT -5 06 (fig. 182). Th is mo untin g base is used with rad io set SCR -619 described in par ag ra ph 189. Base is made u po f two sections wh ic h are connected toge ther throu gh fou r ru bb er grommets. Lower section is fas tened to vehicle bra ckets with fou r cap screws. R adio components ar e fast en ed to top port ion o f m o unti n gbase by use o f snap fasten ers.

1 90 . A n te nn a

M AST B AS E A B- 1 5/G R (fig. 187). T his base is equ ippe d w ith aflexible section im med iatel y above th e po rcela in in sula to r. Th is base is secured to its mo unti ng b rack e t by a cla m pin g ac tio n o f th e porcelain in sul at or and a hex agon al n u t on lower end of base. Th is base isused w ith ra dio sets S C R- 610 and SCR-619.

MAST SE C T ION . The frequency m o dul a ted sets use th re e ma st

R E C E IVE R — T R AN S M ITTE R BC -659

P LA T E SU PPLY UNIT P E-120 MOUNTIN G B ASE FT-250

2 9 1

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6 ose

sections, num be rs MS-116, 117 an d 118. S ec tio ns ar e m ad e o f h igh ten si le steel an d a re secured to g e th e r so tha t ends w ith lik e colo r enamel a re jo in in g . Bo dy o f the m as t b ea rs ty p e num ber . Cl am ps

are p rov id ed to keep th e ma st sections fr o m loosening while in use.These sections a n d sp ar e sections are stowed in ro ll ba g B C -5 6 when n o t i n use.

1 91 . In s p ec t io ns

a. ANT ENNA . (1) In sp ec t a nt e nn a m ast sections to be su re th at th ey ar e securely screwed a n d cla m ped tog et h e r an d ar e n ot dam age d .

(2) See th a t m ast base is secured to its bra ck et o r m ou nt ing sur fac es and s tan ds in a ve rti ca l p o s it io n an d th at in sul a to ris n o t c ra cke d o r chipped.

(3 ) Check leads to set an d be sur e th a t th e re is no in ter fer en ce th a t m ay d am age cords an d th at any stand-off in su la tor sare no t crac ke d or ch ipp ed .

&. M O U N T I NG S. (1) Be sure th a t rad io compo n en ts are securely fast en ed onto m o un tin g base.

(2) W he n rei n s ta lli n g rad io o r in te rp h o n e equip ment, make su re th at all to ot h ed lock washers are rep la ced in lo ca tio ns

w here th ey were o rig in a ll y used.

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BATTER Y BO X C H- 2 91E CE I V E R — TR AN S MIT TE R B C -13 3 5

B AT TE RY C H A R G E R P E -2 1 9 M O U N T IN G B ASE F T -5 0 6

. .

M O U N T IN G B O L T S

Jf8 2 .

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—

MO U NT ING B OL T S

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R A DIO T E R M IN A L BO XC O N T R OL BO X BC -7 39 -A

C ON T R O L BOX B C - 73 9-A

C AB LE T O G U N N E R 'S IN T E R P HO N E C O N T R O L B OX BC-6 06-H

F igure 186 . C ontr o l bo x B C -7 S 9-A .

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(3 ) Inspect moun ting screws to see that they are t igh t and that shock mountings ar e in good cond ition. Rock set an dinterp ho ne amplifier to determine if they bump any other equipmen t,an d observe wh ether shock absorbers are deter iora ted and perm itexcessive movement.

C O R D SA N DCO NNECTION S. Inspect all co rds whic h connect radioor interphone equ ipment to see that th ey are not d amaged; make surethey are prop erly secured in clips. Report a ny damage to pro perauth ority.

M I C R O P H O NES A N DH E ADSETS. Handle microp hones and h eadsetswith ca re to see that they a re hung on hooks provided for th is purposewhen not in use. Be sur e tha t cor ds are n ot twisted or knotted toprevent movement of weare r. Inspec t jac k plug s on micr ophones andhead sets to see that the y are not dama ged.

RADIOTE R M I N A LBox (fig. 186) . Remove cove r and check tightness of al l terminal nuts. Tighten nuts, if n ecessary, to prevent anymovement of wire on termin al stud; by doing this, any possi bility ofradio interfe rence from this source is eliminated. Also check presence and fastening o f condensers in terminal box.

/. C O V E R S .B e sure that cover for p rotection of radio set is available in vehicle a nd that cover is insta lled when equipme nt is not inuse. Seeth a t all fasteners and zippers are in good condition. Cover

BG-153 is used wit h r adio set SCR-610.

MAST SECTIO N MS-116

MAST BASE AB-I5 /GR

TERMINAL BOX J -72/GR(Used With Radio Set SCR-619 Only)

ANTENNA LEAD

RA PD 331959

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192. Precautions

A N T E N N A . Tie antenna down securely when vehicle is in motionand radio is not in use to prevent damage to antenna. Be sure antennais vertical and not touching anything when radio is in use.

i. RADIO. (1) Keep radio covered when vehicle is not in use to prevent dust and moisture from entering set. Keep all cover plates closedand securely fastened.

(2) Turn off all radio and interphone switches when not in use.Do not turn off master battery switch with radio and interphone on.

(3) Do not store equipment behind radio where it can prevent movement on mountings or damage to connections.

BATTEKIESA N DCHARGING S YST EM(figs. 4 7 and 49). (1) Be surebatteries are charged at all times to insure satisfactory operation ofset (par. 46). Low batteries will cause set to be weak and unstableresulting in poor reception, and may make it difficult to start vehicle.Excessive charging rate may cause damage to radio set and interphone amplifier.

(2) S ee that all battery cables and terminals are in good conditionand tight.

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APPENDIX I

SHIPMENT A N D LIMITEDSTORAGE

1. General In s t ruct i ons

Preparation for domestic shi pment of vehicle is the same as pr eparation for limited storage. Preparat ion fo r shipment by rail include sinstructions for loa ding and unloa ding vehicle, block ing necessary tosecure vehicle on freight cars, c learance, we ight, a nd other infor mation necessary to pre pare vehicle properly for rail shipment. For,mo re detailed information and fo r preparation for indefinite storag e,

refer to AR 850-18 and FM 9-25 .

2 . P r e p a ra t i o n fo r L imit e d S t o r a g e o r D o m e s t i c S h i p men t

A v ehicle to be prep ared for limit ed storage o r domes tic shipm entis one tempor arily out of service for less than 3 0 days, or a veh iclethat must be rea dy for operation on call. If vehic le is to be indefin itelystore d after shipment by rail, it will be prepared for such storage atits destination.

& . If vehicle is to be placed in limite d storage or shipped domestically, ta ke the following precautions:

(1) Complete ly lubricate entire vehicle including armament, exce pt engine (par s. 3 2 a nd 33). For preparation of engin e ,see subparagraph (10) below.

(2 ) Check batteries and terminal s for corrosio n and, ifnecessary, clean and tho ro ughly service batteries (par. 84).

(3) After ba ttery check and lubrication servi ces, make

a roa d test of at least5

miles to check on generalcondition of vehicl e.

Correct any d efects noted in vehicle operation bef ore vehicle is storedor shipped, o r note on a tag attached to steering leve rs, stating repa irsneeded or describing condition present. A written report of theseitems will then be ma de to the officer in charge.

(4 ) It is not necessary to remove fue l from tanksd uring temporary s tora ge or shipment within the United States, norto label tanks under Int erstate Commerce Commission R egulati ons.Leave fuel in tanks except when storing in locatio ns where fire ordinances or other local regulat ions requ ire removal of all gasolin e beforestorage. If vehic les are to be m aintained ready fo r operation on callin excess of 3 0 days, take th e following precau tions ag ainst gumformation:

Fuel system m ust be free from accumulated gum. Unlessvehicle is entering its first storage and has never been issued for use,inspect and clean fuel pump, carburetor acc ele rator pump p lunger,

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venturi tube, choke and throttle valves, float mechanism, fuel lines,fuel tank s, fuel filters, fuel shut-off valves,and screens.

(6 ) If gum is present in the above parts, it can best be removedbybenzol, acetone, alcohol, or a mixture of equal parts o f the.se solvents.Deposited gum is no t readily soluble in fresh gasoline. When gum

has dried, it m ay be necessaryto use mechanical means to remove it.Pa rts which cannot be thoroughly cleanedand freed from gum

deposit with out dam age shouldbe replaced.After cleaning and reassembly, fill fuel tanks half full with

fresh gasoline whichhas not been in storag e very long.Add two containers (8 ounces) of gum preven tive compound

to each fue l tank.(/) Fill fuel ta nks to capa city and o perate vehicle for at le ast 5

minutes.(5) When possible, pa rtia lly disassemblebreech mechanism, clean with dry-cleanin g so lvent, and dip or brushinterior parts with ru s t preventiv e compound (light ). Assemblebreech mechanism. Apply a coating of rust pr eventive compound(light) to all exterior portions of the breech.

(6) Clean bore with dry-cleaning .solvent an dthoroughly dry. Swab bore with rust preventive compound (light).

(7 ) S eal the muzzle and breech with tw o layersof grease-pr oof wrapping paper and one of K raft waterproof wrapping paper. Appl y nonhygroscopic adhesive tape over pa per, comp letely s ealing the openings. App ly rust preventive compound (thinfilm) overthe tape as a sealer. If greasepro of wr apper is not available, use canvas or burlap impregna ted with rust preventive compound ( thin film).

(8 ) Install muzzle and breech covers supplied with ma terial .

(9 ) If time and fa cilit ies permit, removerustappearing on any part of the vehicle exterio r with flint paper. R epaint painted su rfaces whenever necessaryto pro tect wood or metal.Coat exposed polished metal surfaces susceptibleto rust, with rustpreventive compound (light). Close all door.s, hatches, vision slots,and other openings firmly. Make sure tarpaulin s are in place andfirmly secured. Leave rubber floor mats, when provi ded, in an unrolled position on the floor, not rolled or curled up. Equi pment such

as pioneer tools, trac k to ols, and fire extinguishers will remain in placeon the vehicle. For treatment of small arms carried on o r within thevehicle,refer to pe rtinent technicalmanuals.

(10) R e m ove spark plugs and spray into top s ofcylinders with preservative engine oil (PE 3 0) while slowly rotat ingengine. Replace spark plugs.

If sp ark plugs cannot be removed, sp ray preservati ve oil into

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air intake with engine run ning at a fast idle u ntil smoke conies from exha u st pipe.

Cautio n: Preserv ative oil m ust never be po u red throug h carb uretor.After spra y ing preservative oil into air intak e , shut off engin e and

allow to cool for about 15 minutes. Start engine an d again spray

preserv ative oil into air in take for several minutes only. Secondspraying is necessary in ord er to coat exh aus t valves. Do no t runeng ine fo r more than several minute s as exhaust valves wi ll becomeso ho t that preser vativ e oil wi ll not ad here prope rly. Perform thistre atment when fur th er ru nning of the engine is not necessary.

If it becomes necessary to run engine after treat me nt, it shouldn ot be operated a t over 1,600 revol utions per m inut e. Hold o peratio nto a m inimum and sp ray cylin ders again after op eration.

(11) M ake a sy stematic insp ecti on just before sh ipment or lim ited storage to insure that all th e above step s have beencovered , and that the vehicle is ready for o per ation on ca ll. Make alist of all m issing or damag ed items and atta ch it to the ste eri ng levers.Refer to Before-opera ti on Service (par. 36).

(1 2) Release brakes and chock tracks.I N S P E C T I O NS IN LIMITEDS T OR A G E .When vehicle is placed in lim

ited storage, inspect batterie s weekly. If wa ter is added to b atter ieswhen fre ez ing weather is anticipa ted, rec harge batteries w ith a port

able charg er or remove the m for char g ing.Cau tion: D o no t at tempt to recharge batter ies by runn ing au xiliary

generator.Remove any rust from vehicle with flint paper and to uch up with

paint o r light pres erva tive compound if necessary. M ake a weekly,visual in spect ion of arma ment dur ing sto rage to determi ne generalconditi on. If corrosion is found at any par ts, remove rust spots andtreat with p re scribed preserv ative .

N o ru st preve ntive compound ha s been developed that will stop corrosion Indefini tely.

3. L o a d i n g an d B l o c k i n gfo r Rai l S h i p m e ntP RE PA R AT I O N .In ad dit ion to the pre paration described in par a

graph 194,when ordnance vehicles are prep ar ed for domestic shipmentta ke the following steps:

(1) C over the body of the vehicle with the canvas coversupplied as an accessory, or availa ble fo r use durin g rail shipment.

(2 ) Disconnect the bat terie s to preve nt the ir dischargeby v an dalism or accident. This may be accomplishedby disc onnectingthe positiv e lead, taping the end o f the lead, and tying it back awayfrom th e batteries.

(3 ) M ove tr ansmission selector lever eit he r toD RIVE or LOW position to move the linkage away from the position stop s, an d to prevent th e lever from being jarr ed out of adjustment.30 0

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(4) All cars conta ining ordnanc e vehicles must be placarded "D O NO T HUMP ."

(5) Ordnance vehicles may be shippe d on flat cars,end-door box cars, side-door box cars, or drop -en d gondola cars,whichever typ e is most convenient.

FACILITIESF O E L O A D I N G. Whe never possible , load and unload vehicles from open cars und er their own power, us ing pe rmanent endramps and spann ing platform s. M ovement from one flat ca r to ano the r along th e leng th of the tr ain is made possible by cross-overplates or span ning pla tfor ms. If no p erm anent end ramp is available,an i mpr ovised ramp can be made from ra ilroad ties. Vehicles ma ybe loaded in gondola cars withou t drop ends by usin g a crane. Incase of shipmen t in side-door box cars, use a doll y- type jack to w arpthe vehicle s into position w ithin the car.

B R AK E S . Loca te th e vehicles on the car in such a m anner as toprevent the car from carry in g an unbalanced load. After the vehiclehas been pla ced in position w ith a brak e wheel clearance of at lea st6 inches fig. 188), apply brak es a nd place the tran smissio n in lowgear.

S EC U R I N GV E H I C L ES. In securing or blocking a vehicle, threemotions, lengthwise,sidewise, and boun cing must be pr evented. Thefollow ing are approve d methods of b locking an d secu ring these vehicles on freig ht cars:

(1) Place fou r blocks (#, fig. 188), one to the frontand one to th e rear of each tr ack. Nail the heel of each block to thecar floor with five fo rty penny nails. To enail to the c ar floor, withtwo fo rtypenny nails, that po rtion of each block which is und er the trac k. Locate two blocks ( < 7 ,fig. 188) on each side of the vehicle on the o u tside of each track. Nail each block to the car floor withthree fortyp enny nails. The se blocks may be located on th e inside

of th e tracks if conditions warra nt.(2) Place two blocks fig. 188), one to the f rontand one to the rear of the trac k s. These blocks are to be at lea st aslong as the ov er-all width of th e vehicle at the car floor. Locate eightblocks fig. 188) against the blocks fig. 188) to th e frontand to the rear o f each track. N ail the lower block to the floor w iththree fortypenny nails and the to p block to the lower block wit h th reefortypenny nail s. Locate and secure blocks ( < 7 ,fig. 188) as expla ined in subp aragrap h (1) above.

SHIPPING D A TA .Leng th , over-all__ ___-_____-_ ——____ 230 inches.Width ____ ______ ____ ___'___ ___ __. 112 inches.H eight________-_— — —— — — — — ——— - — — -96 inches.Ar ea of car floor occupied pe r vehicle——— — —— — . 179 squar e feet.Volume occupied per v e h i c l e —— — — — — —— — —— — — .1,432 cubic feet.Shipping weigh t p er ve h i c l e — — —— — — — —— — — — —— 40,500 pounds.

7520 22 0—47———20301

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2* C H A M F E R A T C O N T A C T POINTBLOC K-F

B L OCK— C

BLOC K-B

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APPENDIX I I

R E F E R E N CE S

1. Pu b l i ca t ion Indexes

Th e following pu blications indexes should be consu lted f requently forlatest ch anges to or revisions of the publi cations given in this list ofreferen ces and for new publicatio ns relating to materiel covered in thismanual:

Int roduction to Ordnance Su pply Catalog ORD 1.(expl aining S NL system).

Ordna n ce Publications for Supply Index WD Cat. ORD 2.(index to SNL's) .

Ordnance major items and combinations, and SB 9-1.pertinent publications (alphabetic al listingof ordnance major items and combin ationswith publications pertainin g thereto).

List and index of War Department Public a- F M 21-6 .tions (list ing FM's, MR's, M TP's, M W O f c,

T/A 's, TC's, WDLO 's, WDTB's, firingtables and char ts, forms, new AR's, changesand revi si ons, personne l classifica tion test s,and pamphle ts).

Li st of Training Films, Film Strips and Film F M 21-7.Bulletin s (listing TF's, FS 's, and FB's, byserial number and subject).

M ilitary Tr aining Aids ( listing gra phic train- FM 21-8.ing aids, models, devices, and displays).

2. S t a n d ar d N o me n c l a t u r e Lists

V E H I C U L A R .Carriage, motor, 155-mm ho witzer, M 41 ORD SNL G - 2 3 6.*

(T64E1).

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M A I N TE N A N C E.An tifr iction be arin gs a n d relate d items——— OR D 5 SN L H-1 2C leaning , pr eservi ng , and lubrica tion ma te - OR D 3 SNL J£ -l.

rials , recoil fluids, special oils, an d miscel laneous re la ted items.

El em ents, oil fi lter__ _ ____ __ ____ _ __ O RD 5 SN L K- 4.Lubric a ting eq u ipment, accessories and re- O RD 5 SN L K -3.

lated dispensers.Miscellaneous har d ware_ ___— _ _____ ORD 5 SNL H -2.Solde ring , br azing, a n d we ld ing ma terials, O RD 3 SN L K- 2.

gases, and rela ted items.Standa rd h ard war e__ ___ __ ___ ___ __ OR D 5 SN L H-1.Tools, main te nance, for rep air of m otor

ve h icles:Tool-sets (speci al), m oto r vehic les___ ORD 6S NLG -2 7(Sec. 1 ).

T ool-sets (common) speci alis ts' an d or- O R D 6 SN L G-27ganization a l. (Sec. 2).

T ools, m aintena n ce, for repair of pack, li ght OR D 6 S NL C - 1 8 .and medium field artille ry ; and a rmamentof these cal ibers for airplane and combatvehicles.

A M M U N ITION.Am mun ition , bla nk, for pack, lig ht and me- O RD 11 SNL R -5.

di um field, ta n k, and an titank art illery .A m muniti o n, fixed and semifixed, includin g OR D 11 SNL R -l .

subcaliber, fo r pack, light and medium field,ta nk, an d antitan k art ille ry, inclu d ing com plete ro und data .

Amm un ition instru cti on mate rial for pack, O RD 11 S NL R-6.

li ght and medium field, air craft, ta nk, andan tita nk ar tillery.

Projec til es a nd p rop ellin g charges, sep ara te O RD 11 SNL R-2.loa ding, for medium field artiller y , includ ing complete roun d data .

Service fuzes and pri m ers for pack, ligh t and O RD 11 S NL R-3.medium field, ai rc raft, tan k, and a ntita nkart il lery.

A RM AM E N T.Howi tze r, 155-mm, M l; and mount, ho w itzer, O RD (*) SNL C-3 9.

155-mm, M 14 (T 1 9).G u n , .submachine, cal. .45, M3_ __ ___ __ _ OR D (*) S NL A -58 .Car bine, cal. .30, M l__ ___ __ ___ __ __ ORD (*) SN L B-28 .

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SIGHTIN GAN DFIKEC O N T R O L E Q U I PM E N T.Bino cular, M 1 3 , com p lete______ __ ___ ORD (* ) SNL F -210.Light, instru m ent, M3 4____ _____ ____ O RD (* ) SNL F -205.Moun t, telescop e and p anoramic , M25_ ____ O RD (*) SNL F- 216.Periscope, M 6 _________ __ ________ O RD (*) SNL F -235.

Post , aiming, Ml__ _______.____ _____ ORD (*) SN L F-35.Qua drant, gun ner's, Ml (mils )—__ _____ ORD (*) SNL F -140.Set, lights , aiming post, M 14_____ ____ _ O RD (*) SN L F-205.Setter, fuze, M 23___ ______ _____ ___ O RD (*) SNL F- 293.Tabl e, firing, graphi cal, M 28 (F T 155-Q-l ORD (*) SNL F -237.

or 2).Tele scope, panoramic , M1 2A6____ ____ _ ORD (*) SNL F-214 .

3. Othe r P ubl icat ionsFU NDA M E N TA LPRINCIPLES.

Amm unitio n, gener al____ _____ _____ TM 9-1900.Amm unition inspe ctio n gu ide_____ ____ _ TM 9-1904.Artil lery, ammu nit ion_______ __ _____ TM 9-1901.Au tomotive ele c tricity_____ _ ________ TM 10-580. Auxi liary fire-c ontrol in struments (fie ld TM 9 — 5 7 5 .

glasses, eyegla sses, tel escopes and w atches).Ballistic da ta, pe rformance o f am munition_ TM 9-1907.Bas ic maintenan ce manua l___ _______ _ TM 38-650.Care and maintenan c e of ba ll and roller TM 37-265.

bearings.Cooli ng systems: Veh icles and power ground TM 9-2858.

equipmen t.Driv er sele ction and tra ini ng_______ __ _ TM 21-300.Dr ive r training, hal f-t rack and fu ll-track TM 21-301.

veh icles.

Dr iver's m anual_____ __ ________ ___ . TM 21-305.Electr ical fundam entals ———___ ——— ____. TM 1-455.Eleme ntary optics an d application s to fire con- TM 9-2601.

trol instru ments.Fuels and ca rbu retion_____ ____ —_——— . TM 10-550.Graphical fi ring tables__ _ _________ _. TM 9-524.Mili tar y moto r vehic les. —_____—— —_ —__ A R 850-15.Motor veh ic le inspection s and preventive TM 37-2810.

maintenanc e service.Ordnanc e ser vi ce in th e field—___—— — — — —FM 9-5.Pr ecautions in handling gaso line_ _______ A R 850-20.Q u alifications in ar ms and ammunit ion, tra in- AR 775-10.

ing allow ances.Ra dio fundamentals—— —_________— —— —— — TM 11-455.

•See WD Catalog ORD 2 Index for published pamphlets of the Ordnance Supply Catalog.

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R adio o p erator__ _______ _______ __. TM 11-454.Ran ge r e gulations for firing am munitio n foi AR 750-10.

trainin g and targe t practice .Servic e of the piece—155-mm. howitzer , M l_ F M 6-81.Small ar ms am mu nition_ __ ____— _ —_ TM 9-1990.

Sma ll ar ms, li ght field m ort ars and 20-mm. T M 9-2200.airc raft gun s.S ta ndard ar t illery an d fire co nt rol instru- T M 9-2300.

merits.Standard m ilitary mo tor vehicl es ______ _. TM 9-2800.Storage b atter ies—le ad-a cid type—————__. TM 9-2857.Targets, target mat erial , and tra ining co urse TM 9-855.

layo ut s.V eh icular gene ral pur pos e unit equ ipment_. TM 9-834.155-mm. howitz er , Ml_ __ ____- __ ____ TM 9-331.

MAINTEN A N C EAN DREPAIR.Cle aning , preser vin g, sea ling , lub ricati ng, TM 9-850.

and re lat ed mate ria ls issue d for ordn ancem ateriel.

Ma inte nance and care of pn eumatic tires and TM 31-200.rubbe r treads___ _ _______ _ _______ _ __

Ordn ance ma inten an ce: Car bureto rs T M 9-1826A .(Cart er).

Ordnanc e maint ena nce: Diff e rential, f inal TM 9-1729C.drives , t rack su spensi on, h ull and tu rretfor lig h t tank M24 and twin 40-mm. gu nmotor c arr iage M19.

Ordnanc e mainten an ce: Electr ical eq uipm ent TM 9 -1825 A.

(Delc o-Rem y).O rdnance mainten an ce: Engin es, coolin g TM 9-1 729 A.

system s, and fuel systems fo r li ght tan ksM5, M5A1, an d M24, 75-mm. howi tze rmotor carriage M8, and tw in 40-mm. g unmotor c arriag e M19.

O rdnance ma intenan ce: Fire ex tin guisher s_ T M 9-1799.O rdnance m aintenanc e : Fuel pu m ps____ _ TM 9-18 28A.Ord nan ce m ai ntenance : Light tank M24 and TM 9-1729 B .

twin 40-mm. gun motor carr iage M19—

transm is sion, transfer u nit, prop ell ershaft s, controll e d differ e ntial and finaldrives.

O rdnanc e maint en ance: Spe ed ometers, ta- TM 9-18 29A.cho me ters, and re corde rs.

PROTECTION O F M AT ERIEL.Camoufl age____ _ _______ _______ _ F M 5-20.

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Camoufla ge of v ehicles___________— _ FM 5-20B.Camouflage of field artillery_______— FM 5-20D.Chemical decon taminati on company__—— FM 3-70 .Decontam ination_ ________________ TM 3-220 .Decontamination of armored fo rce vehicles— FM 17-59.

Defense against chemical atta ck—_———— FM 21-40.Explosiv es and demolitio ns________ — FM 5-25.Military ch emistry and chemical agents___ TM 3 -215.

S T O R A G E A N DS H I P M E N T.Ordnance company , depot___—__——— FM 9-25.Ordnance packa ging and shippin g (pos ts, TM 9-2854.

camps, an d stations).Ordnance storage and shipment chart, group SB 9-OS SC-G.

G —Major items.Preparation of un boxed ordnance materiel for SB 9-4.

shipment.Protection of ordnan ce materiel in open SB 9^47.

storage.Eegistration of mo tor vehicles_______— A R 850-10.Rule s governing th e loading of mech anized

and motorized Arm y eq uipment, also maj orcaliber guns for the United S tates Armyand Nav y on open to p equipment, publishe dby O perations and Maintenanc e De partment of Association of American Railro ads.

Storage of motor vehicle equipment___— _ AR 850-18.

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INDEX

Absorbers, shock----___-_-__-_-___-_______--___-._------ 1 5 2 250Accelerator---_--_-___-.----___---_--_------_-_---___--. 1 0 1'5Air cleaners:

After-operation service-______________---__-__--______ 39 67At-halt service--________------.-----_-_________----_ 38 65Data (carburetor) _--_____ 1 0 8 1 78Description and servicing:

Carburetor-_-_--_--_-_-_-.___________________ 1 0 9 1 8 0Crankcase-----.----------..__________________ 61 1 22

Dusty condition operation. _--__.._-_______..-___-__-__ 25 4 1Maintenance (carburetor)_-._____-_-.__-_____-_____-_ 40 70Preliminary service-_„_____________---__-____-__--.__ 8 11Removal and installation (carburetor)-------------.--.- 1 0 9 180

Ammeter:Installation.-------. ----...-_-_-_----..-----_-------- 90 1 64Location and use--_-----_-___-_-_----.._----_-_-_---_ 12 22Removal____-___--_.-.--.__--___..-._-__----_.-_-_ 90 1 64

Ammunition:Authorized rounds_____-_.--...-.____----_---_-___-_- 1 8 4 279Data.--_-_-----_---_----._-_----_-_------_--------- 4 4Fuzes_--_---_----_.----__-___-_---_-_-_-_-_-_--_. 1 8 6 2 8 1Preparation for firing..-.-.-.-_-.--_-----.---_-_-_-_- 1 8 5 279Subcaliber ammunition--.__._-_---_-__---_--.-__--_.- 1 8 7 290

Antenna______-__________-___________-_-_-----___-_-_. 1 9 0 291Antifreeze.-....----------------_-_-------------------_- 2 3 37Apparatus box.-------__-_--_-___-----------------_---_- 96 168Armament:

Characteristics.---_----_--____-_-___--_---_---__---- 1 70 262Data.-.--------------.--------_--_-_-----.----_-- 4 4Maintenance____---_-_--_-__-_-..-_-----._----_----_ 40 70

Armament operating instructions:Inspection before firing,_____-________-___-___-_----_ 1 73 265Operating breech mechanism.___--__-___-__-_-.___--__ 1 76 267Placing weapon in firing position....--.------_-._-_-.- 1 72 264To elevate..--------.--..---------------------------- 1 75 266To fire--.----------------.--..--------------------- 1 77 269To place in traveling position-______-_--------_---_-_- 2,19 1,29To traverse.-----------------.-.-.------------------ 1 74 266To unload-----------------.-..-------------------- 1 78 270

Auxiliary equipment, operation of---___-----------_--.____ 2 1 3 4Auxiliary fuel filter, servicing. ____________________________ 11 0 1 8 2Bars, torsion—_-_-_..--_-_-_-__----_.__--_--.-----.__-- 1 4 2 , 1 4 9 2 3 2 ,247Batteries:

After-operation service.----------------.-.-.--------- 39 67Checking-__-__-_---_------_-------_------------_- 84 1 5 9

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Batteries —Continued Cold weat her prep aration ___--_ -____ ____._ _----_ __-_-- __ 23 37Co rrosio n of te rmi nals.--- ---- --.--.-. -.--- -------- -.-- . 84 159Dat a_--__ ---_ ----__- ___ --.__-_ __-. -.._-.-- .---- ---. 83 156Elec trical circuit, troub le shooting- -_- _______-- --- ______- 44 95Maint e nance_-___ _ --__--____ .--___-___-_ - ----__-__--- _ 40 70Ma ster switch, d ata _____-- --_ ____-._ _--- ----_-_- ---- 83 156P relimina ry s ervice __-. __._... _._.. _...._.. ._._ ........_ 8 11Removal a nd instal latio n:

Ba tt ery-...-- -. ..-.----..- -. ----..-_- -- --------- 84 159Cables----- --------__-- __--__----- _----------- --- 84 159M as terswit ch_ _.___ ..... ........._ .-._ -........ . 85 160

Usi ng arm se rv ices.---- --- -.---.-.-- -- .-.--.-.-- --- ---. 84 159Batte ry and lighti ng syste ms .-.---..-- --- --------- --- ------- 83 156B a ttery maint e nance (se con d echelon )_ ---_------- -- --__------ 40 70B elts:

Adju stme nt an d r ep lacemen t-- ---.--.--- --- --.------- --- 59 117A fter-op eration service__ - _---_--__- _ ------------ -- --_-_ 39 67P re liminary ser vice.- ...--- ------ ------ ------ ------ ---- 8 11

B ore sightin g. .-_.____. __ _...__-... __ ----.._-__ - -.-_------ 182 277Box. appa ratus.._ ._--- --____ --__ ----___ ----_ _------- __-- _. 96 16 8Box, co ntrol, elevati on mec hanis m..._. _._-.. -_-_--- -_-_- -_-_ 19 29Brak e band adju stmen t....-- _-_.-- _----- ----_- _----- _---_ _ 134 220B ra ke linkage (steering)._ _ __.___-__- ____--_-__- _ __.-_-..... 36 62B rakes, par king, run -in test_-- _ -.._.-_-._ _ .---------- ----. 9 14B rak es, steer ing:

After -operat ion se rvice_--- -_ __-------- .-_ _-------- --- _- 39 67

A t- halt servi c e--------- - ----------- -- ----------- - ----- 38 65Before- op eration ser vic e.--_--_ ---_ ---_--_- ---- --------- 39 67During- o peration serv ic e---.---- --- --.------ --- ------.- 37 64Main t enance--- - --.----.---- - ---------.- -- ----------- - 40 70R oad te st___._____ ______-___ __-___-.--_- ---___--_--- 40 70Run- in test,- _--- -_----- _--_ --__--- ---_ -------- ---- --- 9 14

Brakin g lev ers..._ ----- -_---_ ------ _--.-_ -_-_- ------- ---_- 10 15Breakers , circuit. Circuit bre akers.)B reathe rs:

A fter-oper ation ser vice-_- -___ _------ ----- -------- ----- - 39 67

Dusty cond ition operat ion.----..._ .___...----_ ._---.... 25 41P rel iminary serv ice -.-----. -.-- --------- --- --------- --- 8 11

Breech mec hanis m.-.. .------ ------ .--_-- ------- --__- _----- 176 267Bu lkh ead 157 254Butt ons, sta rte r...-----_ _ --_--_--- --- --.------- -- --__---.- 10 15

Carb uretor:Adjust men ts:

Ca r buretor.. 1 1 0 1 82Throttle linka ge—-- -___ --____ 110 182

Da ta.... ..... 108 178D escri ption ....... ....._- -....- -----.- -_.-- -----_ -.--. 110 18 2In stalla tion. _._ .__ ...._.... ..... ..---.-.- --- .--_-_- -... 110 182Mai nten ance.- .--- -------- ----- -------- ---- -.-.----- -- 40 70Remova l-...--..-_.- -.__._.-... . ...-__.--.-- -.-_--..- 110 182S ervicin g fuel filter ( aux iliary) .-.-- --.------ --- --------- 110 182

Char ging system :Descr iption and d ata__.... . ._......... - -..._....- - .. 80 152Trou blesh ooting -.... ...---.-- ___ _.-_.-- --_-_ --_--_ _ 46 100

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Choke: Location.--------------- -------- -------.------------- 10 15Preliminary service---__-_-- -_-- --_----------------_--- 8 11

Circuit breakers:D a t a . . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8 3 1 5 6

I n s t a l l a t i o n _ - - - _ - _ _ - _ - _ - - - - _ _ _ - - - - _ _ _ - . - - - - - - _ - - - - - - _ - 8 6 1 6 0

R e m o va l . - - - . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8 6 1 6 0

Cleaners, air. Air cleaners.)Cold weather operation:

I nspection.-- ---------------------- ---.-.--------- ---. 24 40Starting and op eration---_-__------ -_---_----__--- ---_- 24 40St opping engines-------- ------------ ------------------ 24 40Vehicle starting_______ __-__________ ..____-____----_-_- 24 40

Cold weather prepa ration:Co oling syst e ms__---------_---_-------_-------- - -_---- 23 3 7Electrical s ystems----.------.---.--------- ---- -------- 2 3 3 7Fuels ___ _-----._--_--.__-_------_---- -_---_ ------_--- 23 3 7General- ----------- ---------------..------- --------- 23 3 7Lubri cation-__-___ __...-__-----.----_.__ -----_-------. 23 3 7

Communications, data._ -----------__--_-__--.---_--------- 4 4Compensating arm and lever:

Bearing adjustme nt..-.__ -_-__._._-_...-_-__----__--_ __ 146 23 9Removal and ins tallation_-_--.-- -__-..-___----.-_-- -_.- 146 23 9

Compensating link.. __-____--._-___ _---_______--_-__-_- -___ 146 241C ompensating wheel, bearings, an d seals:

Adjustment_______ ___ __----___---..__-.----.-------_ 145 23 7Installati on..-------------..----. ....--..---- ..----... 145 23 7Removal.---------------- .----- ---------------------. 145 237

Condenser, distributor.------------- --------- -------------- 72 145Contact points, distribu tor:

Accessibility.-. .._-----__-- -------.---_-.--_-----_-- -- 70 143Adjusting, clean ing, inspecting...-.-----.-- __-__----_ --- 70 143Re placement_ ____-___--_-_-__-_-._. __-_-----__- _---- 70 143

Control, spark-- _ -_.--_-----_-----_._-_----_-----__ - ----_- 10 15Controlleddifferential. Differential, controlled.)Controls:

Fuel pump-._-_.___-- --__-_----__ --------------------- 10 15Howitzer mount--------_.___---- ----- ----------------- 19 29Miscellaneous o perat ing.---.__---.-._--_----_-_--_ ----. 11 20Shifting- -------_-. -..---..-.----.-..---- ----_-__----. 10 15Use of-_-..----.. -.-_-...-.-.-_._.-. .---_----_----. - 13 25Vehicle operating-_ ___-__.___-_-____.__. __---__--__-._ _ 10 15Ve ntilator-....--__._._.-___- .--._-_-- --.----__--_-_-- 11 20

Cooler s, oil. O il coolers.)Cooli ng system:

A dding cool ant_--_--- -_-------_---------------- ------- 115 194Cleaning---.....-.-- -.---.- .-.--.-....---_--_-__---_- 115 194

Cold weather prepara tion..._--_--_-- ----_------_------- 23 3 7Coolant service..-_- _-__-__-- -_-_------__-_------------ 115 194Description and da ta__ ____........_.....--...----... . 114 191Drai ning and filling--.__ --_-_-.-._-_--- _------._------- 115 194Du sty condition opera tion.------------ ----------------- 25 41Flushing- —..--.-..---- .---.-.-----.-.- ------------. 115 194Leaks.--,._.---- ---... _----.----.-..-.---_----_--.-- . 115 194Maintenance____-.-_ _-___---__ -----__-_------------- 115 194

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Engine—ContinuedCylinder head gaskets_------------------------------- 60 119Data——---------_--------__----.--____-------_-- 4 4Description...__________________________________________ 56 114During-operation service...-_-__...-____.._-___---._.-__. 3 7 64Flooding_----__-____----_-_____-.---____-___-_-------_ 14 25

Heat signal unit..---........_-----------------__.. 97 169Input clutch lever--.. .--.. .. .. .. .. --._.. .. .. .. .. .. .. 1 3 1 21 7Installation.,.......-....._._..-.'.-.-.-...---.----.. 67 129Intake and exhaust manifolds..---..-..-.-___.-------... 65 126Maintenance:

In vehicle........................................ 5 8 1 16Road test____..........._-------------------- 4 0 70

Mountings___-_....--.-. -. ...__-------__._ 66 128Oil filt er—-.. .. .. .._.. .. .. .. .. .. -.. .. .. .. .---.-.-... 62 1 22Oil pan and gaskets__---_______-----_-_____--_------_ 63 125

Oil pressure warning signal switch-.----__._.-.--------_- 97 169Oil pump strainers----.-....-..._.--...---.._-----.-__- 64 1 26Removal.._..__...._............__--- --_... 67 129Run-in test-.........._._............_..._..--------.. 9 14Starting of_--- --- _.._--- --- --- -__--- --- --- --- - 14 25Starting one with the other--......--.......-----.-.---. 14 25Stopping:

General.---..---.......--....---._------------- 17 28In cold weather.._---..__._..------__.-..---.---.- 2 4 4 0

Temperature gage unit.-.------------------.----------- 97 169

Temperature gages:Location. _------._--------....---------.-_-_-.-.. 12 23Removal and installation.-_________________________ 91 165

Troubleshooting............_____...____--.-.._ 42 90Tune-up__.__-_._____-___-__----____-------- 5 7 116Warm up—----.--...-.-...-....----.-..._..--------- 8,14 11,25

Exhaust manifolds. Manifolds.)Exhaust pipes:

Maintenance---------.-------.--------.-------------.- 4 0 70Removal and installation,.-.._..._--._-__._._---------. 11 3 1 8 9

Extinguishers, fire. Fire extinguishers.)

191Fan and radiator. Radiator and fan.)Fenders preliminary service.---________------_--__---_----__ 8 11Filters. Oil filter and Fuel filter, auxiliary.)Final drive:

Description and data___..__.__._----.___-__-----.---- 13 9 229Maintenance_.-.....----_-_._._-----_---._---.-----. 40 70Replacement—.-------..--.-.------.-------------.-.- 141 23 0

Fire control equipment. Sighting and fire control equipment.)Fire extinguishers:

After-operation service----------------------.----.----- 3 8 6 5Before-operation service.-------__--------__.---------__ 3 6 62General-.---------.----------------------..----.--.-- 21 3 4Handling.,---.-----.------_------.-----------------_- 167 260Installation...------_-_---.----_.---------.--.-----.-- 167 2 60Maintenance..---.--___--------__-----.-._----------.- 40 70Operation of-.---------.--------.--.----.-..-.-------- 21 3 4

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Fire extin g uishers—ContinuedP reliminary service ---......-.__-____ ___ — —-______. _ 8 11Remova l- ------------..----..----.----._--- -- ---.-- 167 2 6 0

For ms__________-----_----_ _______. --- — .-----__---_-- 2 1

Fue l filter, auxiliary:Data—------------"--.----- .---- ----"------------- 108 178Servicing _______--_ _---_-_-.--..-.--------- --.--...- 110 182

F uel pump con trols..----.--.--.--..-_-.-_- -_---_ -.------ 10 15F uel pumps:

178Descr iption.--.-.____________-__ __._____ _-----_-_-_- Ill 186Remo val and install ation. __.-._._----_-__.---------.. Ill 186

Fuel strainers, data______ .-_-_-_____ — —— -___---------- - 108 178Fuel switche s, removal and installation..------- ------.-..— 102 172F uel system:

4,108 4,178Descr iption——— — — ———___— — — — -_ — ------ — --- 108 178Troubleshooting .. — _— __-___— — — — — — —-- — --- -- 50 111

Fuel tanks:Des cription a nd draining...____._ --_---_ -_-______.-_- 112 188Ma intenance-- .. — . —____-__-_._ — — —_— -_-_-_ -_ __- 40 70Removal and installation. -.--._..----_-----_- .-_-____ 112 188Replacement of lines—. — _----------------------- --- 112 188

Fuels, cold wea ther prep aration----_____._ .___._---_--___- 23 3 7Fuzes --_________. _____— —___ — ___-_-_ -____- — — —- — — 186 281

G a g e unit, engine te mperature-....-.-- ---------------- --- 97 169

Gages:Engine temper a ture-------------......-.--------._- _ _ 12 23Roa d test ____ — — _ _—___ .._______ — __— -— — _-____ 40 70Ru n-in test-----.-- -.-.---.-..------- --------------- 9 14

Ga sket, cylinder h e ad-.--------___...--.---__-_.___- _ -.— 60 119Gaskets, oil pan... -__---- --_--._.____ — ___. — —-__ _— 63 125Generator:

Data—.--- -.-._------_._.-.- -._-______------ --.._- 80 1'52Installation.---------- .-._._---- -------___._..._-._- 81 153Maintenance__ _____________._ -_ -________-_ — — — 40 70

Removal- .--- --- — -------------------- ----- ----.--- 81 153Generator and charging system..----.- ------------ -------- 80 152Generator regulator:

Dat a-____________ .--_.-.---____-___ ._.---.--._.__ 80 152Installation....... ............--_-_ -__-_-___-_.--._- 82 154Maintenance......-_..- ----__---- -___-___----_---._- 40 70Removal.--------.-.- ---------- ----__-_-.-----.---- 82 154

Gun mount. Howitzer mount.)Gunner's plat form_______-_ ---_._.__________ _ — — -_-__ 20, 165 3 1, 259

H andwheel, trav ersing.-._ _..._...._----__________ -----__ 19 29Headlight, rem oval an d insta llation .____-____-__ — — —--___ 87 161Headlight sealed unit, remov al and installation__________.--. 87 161Hoses and connections , cooling system---.---------- ------. 116 196Howitzer mou nt:

Controls-----.-----.-.-.-..-- --- ------------------.. 19 29Descriptio n -___________________------------ -_ _.___-- 3 3Elevating (electric a nd manual) -_-_-____-_-- -_-------- 20 3 1Operation--- -------- -.-----..--------_-------- — --- 20 3 1T raversing__------ -------------- -----------_.-.- 20 3 1

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H owitzer tra vel lock--_-_--____------ _______-.- --_--____--- 19 29Hubs ,---._--_--------_-_- ---_--------- ---_-------------- 140 229Hull:

Armor th ickness data --__------ ----____------ _-------- 4 4D escription--..--.. _-___---_--___-. _-_----r------____ - 3 , 154 3,2 51Preli mi nary service._-----_-___ ___-__-- -_-------__----- 8 11

Hydramati c tr ansmissions. Transmission.)

Ign ition, trouble shooting-__-___-.____ ......._ _-_-_--_-_____ 43 95Ignition coil, data----_-___-__- -------__-------__ --____--_- 69 141Ignition condenser, da ta- _-_-_____-__-_-.__----_-----____ __ - 69 141Ignition switches :

Description- _-_ -_..--_-___._---__-_._--_-_-_--._ __ _-_- 10 15Remova l and installation:

Emergency ignition-____---- -_ --_---_-_------------ 99 171Ignition----.--------.-----..-.-- -- --------------- 99 171

Ignition system:Description a nd data__---_---___-_-____----- -_ ___-_- 69 141Spark plugS---__ ______-__--- ----_.._._-______----_ -_-. 75 149Timing ad justment_--____- _-_---____--___ ------------- 73 146Wiring.-____----._..-.. ._._._ -_------..---_-_-_------ 74 148

Instrument panel:Descriptio n.______ _---_-.-.-._.--_-_-__------ _-_-__-__ 88 164Re moval and installation.____-_ -_-__-_ -_--_-___-____-_- 89 164

Instr uments:After-operation service. ___-___-_-_-.__--_-____ _--_---_- 39 67

Bef ore-operation service._-_-_----_____ _ --_--_---_--_--- 3 6 62Carrie d on panel- __ ____-_-_-_____-_-___-____----_--_- - 88 164Descriptio n .-____________.-._._._------_-_.- _--.--_... 12 23D uring-operation service.-- -.---- ---------------------- 37 64Prelimina ry service---_-____.__ _---_-_-_--- -----__-_--- 8 11R oad test----------.-__----- --.-_- ------------------- 40 70Run-in test---- --_ _______-_--_--.--.-----------__ -- -_- 9 14

* Trouble sh ooting-__--_-___-___-._.-_-__ _--__ -_,-___--_ 47 103Use-..—--- ---- ------------------------------- --- --- 13 25

Intak e manifold. Manifol ds.)

In terphone equipment. Radio and i nterphone equipment.)Lam ps. Lights and lamps.)Levers:

Engi ne in put clutch--.---------- .---- ------------------ 13 1 217Range selecting---- -____ __-__---__---_---_-----__---- - 10 15Steeri ng and braking-.-------------_---_ _- ----_-------- 10 15Transf er unit shift_____--_____-- ._---- -__--------______ 10 15Winch brake____.____ _--_ _____-._._._-----____-______. 19 29

Lighting sw itches__________ ___________-._. -_-._l.._____.- 10, 101 15, 172Lig hting system:

Descri ption and data,.- --______-._-----_-----_--_- _---- 86 156Trouble s hooting.--_----_---- ---_.___..--- ------.-._.- 45 97Lights and lamps:

A fte r-operation service--------__.________ ____ __-_-_____ 3 9 67Before-operation serv ice.________-____-_--_ _------___.__ 36 62D ata ...-___-_----_-_____----__-..-___ ___ _-___-_-_____ 83 156General---------___-- -_-__ ___-----_-_.----------_.--- 87 161Maintenance------_ -_ --_-__-----_-----___-____-_______ 40 70Pr el iminary service..-------- ----._. -._.-----_-_....... 8 11

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Paw l, winch locking _____ ______ _-____ ______ ____. .____-_ -___ 19 29Pedal, ne utral-- --.- -.--.---. --- --------- -- --------- --- .- 10 15Periscopes:

Genera l.. ---------- -- --------.- -- --------- -- ------- 22, 161 35,2 5 7M aintenan ce.. ..---__-_ -_-_ ___-.___ __ ____---_ ___ __-_ 40 70Periscope M 6---__.._ ._ ..-.__.-__-_ _ _____-__ _ -______ 183 279Re pl acement --- --..-_..-- _- ------_-_- _ __-------- -. -. 22 35

Pipe s, exhaust. Exhaus t pi pes.)Platf orm, gunn er 's:

D escrip tion. ... ____ _.-_-_ _--.-__ -____ ______ ____ _____ . 165 259Operati o n.--.----- -- -------.-. -. .....-..--- -- ----.-- 20 31

Pla tform lock ----- ------ ------ -----. .---- ---.--- ----- -.. 19 29Pow er train , description .__________ _ __________ _ __________ _ 3 3Pre v entive m ain tenance:

Afte r- operation and wee kly services ..____ ______ _____ __ 39 67Arm a ment_--_-__ _ -___-_____ ---_--______ __-_______ _ - 40 70A t- halt servic e.-_-_ -__-_ ----___ ____ _____ _.----_ --_-- 3 8 65Batt er y main tenan ce (second e chelon )_.._. __---_ ____._ 40 70Befo re -operation se rvice.__ _____ ______ _____ ______ _____ 36 62Cre w mainten an ce-----. ... ..........._ ... -_____-- -_ . 35 61D efinitio n of terms_ __-..-- _____ .____ ___-- _____ ____ 34 61Durin g-opera tion service. .---__ ___- --_-_-- ----- ---__ T 37 64General inform ation- -..--_ _____ __..__ .--._-- ---__ -___ 34 61Road tes t_.-_..-__.__ - _________ _ _________ _--____-- 40 70Tools and equi pm ent---- --. ..--.---.- ..- -.-------- -- - 40 70

Propeller shafts :Description and data__ _ _________ __ _________ __ ______ 126 21 0Fin al drive shaft_ ______ ____ _______ ____ ______ ____ __ 12 8 212Main s haft..--_-. ..- .________ _ _________ _ __-______ _ 12 7 211Main t enance.-.-- - ____--_-_- _-___-_-__ __---------- - . 40 70Prelimi nar y servic e.--- --__-_-- ____ ______ _--__ ______ _ 8 11T rouble sh ootin g......._ ____ _______ ____ ______ ____ ___ 52 112

Protecti ve p ads___ ___ ______ _.-- .-_-.-._ _..-_ -----_- _-- 15 8 25 4Pub lications --.-- -_-_-._-_ -_- _______ ___ ______-_ _-_ ___.__ 9 14Pumps. Water pum p, Fuel p ump , and O il pum p.)

Radiat o r:D ata— ----- ------ ----.- ----- .-.--- .-.-. - ------ ---- 114 191Main t enance-- - --------.-. . -..-.-..-.... . -------.--- 40 70

Radia tor and fan, remov a l and instal lat ion.----- .--- --.----- 11 8 199Radi ator ther mos tat:

I ns pection .... ......_-.- ..- -_--_--- -_ -----.._. -.. ... 117 196Remov al and insta llation ._..- ---_-_.- __-_ ---_--- --__ - 117 196

R a dio and inter phone equ ipm ent:Antenna__ _ ________. _ _________ ----___.--_- -------- 190 291Gener al-.- --..-._ .-_-- ___-_ ----- _----- --...- ...-.-- 188 290

I nsp ections --- ---.----- --- -------- ---. ----.---. --- -- 191 292Mo untin gs_.-_ ---_ -----__ ----- ----__ .__- -------- -- 189 290P recautio ns. _.__-__- -.- _......-. — .._ --_ _----- ---- 192 297

Radio interf erence suppression :Com p onents.-- .- -_--.__--_ . ..-_..__._ ... ------_--- - 106 173Descr iptio n-.-.-- --.-. ---_.__ ___ _____ ----- -_-.-- 105 173M aintenan c e-.----.--- - ----------- - --------.-- - ----- 10 7 177P urpo se— --_._ ..._. .-..... ---._- -..-_ ---...- -.--- 104 173T roubl e shootin g ..-..-...- ._ .___.. ... .......... . 48 107

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Range selector lever.__ ___.___--___-_-_-_ ___--------__--_ -. 10 15Records--...--- ---------,-- -----__------_--------- .------ 2 1

Reflectors,p reliminary service.__-__-_--_-_--- --- --------_- 8 11Regula tors, generator.__________________.. ____ ---_..___-----_ 82 154Relay, starter.-- .--.-.-__--..._ -____-------_ -__ 79 152

Road test.._. .._ .___-__..__ ___ _- 40 70Rollers, supp ort--------_-_..._ ---------___ _____ 151 248Run-in te st.... ... .._ ....__........_ __. .____ 9 14

Seats:Ad justment of drivers' seat.--_._ --_-__ -.--------_------ 11 20Removal and installation.._-.. ......... ......_...-----. 159 255

Service upon rece ipt of equipment:Correction of deficie nc ies...-_.._-----.._--------------- 7 10Purpose--.....-- _.__... ..____1 __._.--_.-- 6 10Specificproc edures__---_-_...--- _..__------- -.------ 8 11

Shields, pre liminary service.--------_----- ---- -------.------ 8 11Shift lever, transfer 213Shifting controls...----__-.-__----_ .---_--_---------.------ 10 15Shipme nt and limited storage:

Generalins truction s..-----.__-__..._•..--- _- — --. App. I 298Loadingand blocking fo r rail shipment.....--.-. _--- ----. App. I 298Prepara tion_-. ........_..........._....---- -------- - A pp. I 298

Shock absorbers:Data___... .----_...._.__._._ ___-------_ _.._ 142 23 2Removaland installat ion.----_ __---__-__--------------- 152 250

Sightingand fire control equipm ent:Bore sighting .. .. .. .. .. .. .. .. .. .. .. .. .___.. ._ _. 182 277Characteris tics-.__ --------------____---- --__ 180 274

Signal sending units_--____------___-----_._- - -----.------ 97 169Signal unit, engine h eat--- ------.----------..-----:---- ---- 97 169Signals, warning (oil pressure)__-_..----....---- - -----.---- 12 23Siren:

After-operat ion serv ice.-_-______----_____----- -__---- -_ 3 9 67Before-operationservice.----_ --.-----_._.---- ---.------ 3 6 62Locationof swtch. ._ -.. ___._..---_---— 10 15Preliminar y service .-_--_----_-.--___-------- -------.- - 8 1 1Removaland installation of siren an d siren switc h. _.--..._ 98 170

Solenoid, starter_.-._-...--._.__ — ---___._------- 78 152S pade—-------- -------------_- --------.._____ ___ 166 259S pade and gunner's platf orm, operation o f. ------------------- 20 31Spade travel lock_....__.. ............_ _.._..._ 19 29Spare parts (org an izational)__-.-._------.-.------ --_ ----- 30 46Spark co n trol....--....-----.......--....... - .--..------.. 10 15Spark plugs:

Checking gap.--------- ---_.._...____ ----------- 75 149

D ata_-._._.. .. .. .. .. ___. _ _------. ;----. 69 141Removaland installation.. _..__ ._--_.._..-----.._------ 75 149

Speedometer:Descriptio n.... ._ _........_.______-- - ----- -- 12 23Removaland installation.. . ..............-----.-._----. 92 165

Sprockets and hu bs.............__ ___...____. ...___ 140 229Starter:

D a ta-..--.-.-.-......-..-.....--... ... .-------.----- 77 150Installation..___ ____________._______...- 76 149

75 2022 O —4 7 — — — 2 1 317

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Star ter—ContinuedMai ntenance------- ------------------- -------------- 40 70Removal---_ 77 150

Starter b uttons__-.----------------_---- - ------_------- 10 15Sta rte r relay----------- -_----------- -- — ------------- 79 152S tarter so lenoid--------_------ ___---- ------------- 78 152

Starting switch es.-_----- -------__..__._... ._.. 100 172St arting sy stem------_ ----- -_---. _---- ____----- 76 14 9Starting the vehicle by towing---- ---------------.......- . 18 28Steeri ng ...-----------_--------------.--- -- -----------_- 15 26Ste ering adjust ment------ __-_- ...__._------ --- 1 3 4 2 20Steering and brake sh oes--------- -----.---------...---.- - 13 5 2 2 1Steeringbrake link age_-..--_.__-__.- .-_.-..-__._... ..._ 3 6 6 2Steering brakes. Brakes, steering.)Steering lev ers--.-------------- ------------. ---------... 10 15Steering linkage-- --.-------------------- --------.-.-- --- 8 11

Sto pping the vehicle.--._..-.-__. -.-...._....._.._- 16 27Storage. Shipment an d limited storage.)Strainers, oil pump, installatio n-----------------....-- _-__ 64 126Subcaliber amm unition____ ______________________ _______ 1 8 7 290Submersion, vehicle-- _-__-_-_---- --__-----_----_--__---- - 26 42Support be arings (propelle r shaft)--------------- ----- ----- 12 6 210Support rollers, bearings,an d seals_-- ----_---_-__ _-__--_- 151 24 8Suppressio n, radio interference. Radio in terference su p

pres sion.)Suppression c ompo nents------.------.--------- -------- --- 10 6 173

S uspension and cushion stop--__-----.---_-- ---_ -_---_--_. 153 251Suspension arm:Data—--.------- -._-----_---- --------_----_--_--. . 142 23 2R emoval and installation .__-_--_--.__-_----_-.. .._._. 150 248

Suspensionarm cushion shoes, d ata__---_---_-_--__....__.. 142 23 2Suspensions:

After-operation servi ce --------.-.-----------.-------- 3 9 6 7At-halt s erv ice---------.-.----___.._ _._ -_... 38 6 5Before-operations ervice--------------- --.---.------- - 3 6 6 2Description and dat a__ _--- --- -_.--- -- -... ..._.. 14 2 232

Maintenance.----.- --.--___---__ --___----_---------- 40 70Prelim inary service.__-_____________._- -_..- _._._____ 8 1 1Run -in test ,--- --- --- ---___ .__---. .--. .. ...-... 9 14Trouble shooting-_----_-_--_---------__ _--- __-__--__ 55 114

Switches:Fuel....__-----.-.-. -----. ---- — ------ ------------ 102 172Ignition_----- ---- _---- -- ____.------. ........ . 10, 9 9 15, 171Lighting-_----- _--- ----_____--_-. ......_-- 10, 101 15, 172Limit control (howitzer mo unt)- --.;------------------ 19 2 9Master battery___-_--- --- ____--.--...-.....-- 10, 85 15, 16 0

Si ren__---------_---------_ __ __--.. ......-. 10,98 15, 170Start ing-. - ------- -__.....___.._ ____._ _. 10 0 172W arni ng si gnal, engine oil pressure.-_ ..._----------- 9 7 16 9Warning s ignal, transmissio n oil-p ressure.---- ---------- 97 16 9

Tachomet ers:D escr iption.-------.-------------- ------ --..--._.--- 12 23Removal and installati on.--------------_--- ._.._.__-- 92 16 5

Taillight a ssembly.-------.--------------- - -------------. 87 161Taill ight lamps_._........ ......._ ................. 87 161

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Tanks, fuel. Fuel tank s.)Tarpaulin, preliminary servic e... ..----___._____------_______ 8 11Telescope,panoramic, M12 A6_„-__ __.____-------___-..._ 181 275Telescope mount M25________ _____________--- ---_--.-.__ 181 275T emperature ga ge s, engine. Engine temperatur e gages.)Test , run-in__---._--.__ ...... ______-----_____... 9 14Ther mostat:

191Radiator-.-. . ................_ .___....._ _.... 117 196

Timing adjus tment, igni tion system...._..._.. ..- .'. — --_.-.._ 73 146Tools a nd equipment:

Battery maintenanc e.-------. ----------.-----.----.---- 40 70O rganizationa l....------------.-_- .---.-_---_----- _--- 30 46Preliminary service-------------- -------.---- ----.---.. 8 11S pecially d esigned--..----------------- ----- ---.-----.- 31 46

Torsion bars:Data —.------------------.- ----:------ ------------.- 142 23 2Identifi cation....... ..._......_........-. -.-.-.-.-.. 149 247Removal and inst al lation.-.-.'--.-_-----_-------l--- -- -- 149 247

Torus member (tra nsmission)__--- --___---._----.-.- -_--_-- 12 4 207Towing connections- ---------.----- ----------------.-.--- .- 8 11Towing disabled v ehicle„.'.._.-.._..._.-_-.- - .-.-._ 18 28Towing procedures._ __-_-.-----------.. _-..------------ -- 18 2 8Towing to start th e vehicle..........._.- .--.--.-.--_ ----.- 18 28T rack and suspension:

Compensating ar m and lever_--------------- -.-_--- ----- 146 2 3 9Compensating link...----_ ---_--_- -----_.-.------------ 147 241Compensating wheel, bearings, and seals.-_-_-_---_.-.._. 145 23 7Description an d data__---------_----------- - ------ 142 23 2Shock ab sorbers----- -----.------..-_--- .....-.------ 152 250Su pport rollers, bearings, and seals..-„ -.-_-------------- 151 248Suspension and cushion stop..---------_.--- _-- --------- 153 251Suspension arm--..-..----- -..--_- --------.-_------.-- 150 248Torsion ba rs-..----- --.-.__-------------- ----_.-.. 149 247W heels,bearings, and seals.-... -...-_.----.---..----- _-_- 148 242

Trac k shoes, d ata___.._...•. ...-.. .. .-...--.. --.--. _-. .. 142 23 2Track support rollers, da ta------- -----------------_.--_ 142 23 2Track suspen sion system, dusty conditions operation.. ------.- 25 41T rack wheels, bearings, and seals----_ -_--_-_---.------------ 148 242Track wheels, data---.. -.-.-.-- -------------------_---- - 142 23 2T racks:

Adj ustment_....--....- .-...........- .--- --- --. --- . 143 235After-opera tion servic e._ --__-----------_.--_----------- 39 67At-halt service.-- ------- --.--_-.-.----.--------... -. 38 6 5Before-operatio n ser vice.---------.-.------------ ------ - 3 6 62Data— - — - — - — ----.----- — _- — ------------ — - — -— 142 23 2Maintenance----------.-- ----- .----------------------- 40 70Preliminary service.--------- ----.----------- ------.--- 8 11Replacement_--- --------- ----_-------------------- 144 236Run-in test------------- ---. -----.-----..------------- 9 14Troubleshooting ------ -----------.---.-.------------- - 55 114

Tr ansfer unit:Description and data.----.-.----- -- -------------------- 129 213Durin g -operation service..._ ._-.------_ -.------------- 3 7 64Maintenanc e.---------- ----------..------------ ------- 40 70

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Transfer unit—ContinuedReplacement_— — _— — — —— —— _— — — — — — — _-_ — 13 2 21 7Run-in test.. —— — — — -_- —__ — _-------_--____--- — — 9 1 4Shiftlever___.__---_-.-------------------------------- 10 15Trouble shooting-- — - — —— _ — -__ — —_______________ 5 3 11 3

Transfer unit shift lever:Description and replacement.. —— — — —— ___--_---_ — — 13 0 21 3Installation-..--------------.--------.---------------- 1 3 0 213Linkage adjustment___------___-_-_--_------_--_---- 13 0 21 3

Transmission:Band adjustment—-_.----------------------.--_----- 1 2 2 204Description and data—— — —— ——— —— — — —— — — — _ _ 120 203Drain-._..___-___--------.-__--_------_---.-.---_---- 1 2 3 205During-operation service _______________________________ 3 7 64Maintenance__-___------__--_-___-------_-_-----_-_- 40 70Manual control linkage adjustment.._---__-_----_---.--- 1 21 203Oil pressure warning switch.....--_.----_-.__----_.----. 97 1 69Refill-----.-.-----____----.--..---_------------_---_ 1 2 3 205Replacement______--_---.----._---____-------_ 123 205Roadtest-____--_-------_--_--_-_-.___------------ 4 0 70Run-in test-_-_---__--_------_-------.-_-_-_---_---.-- 9 1 4Torus member replacement-_-_-_-_-_-_---_---_____-___- 124 207Trouble shooting. _-_ — —-_ — ____________________ 51 112Valve body---------------.---.------.------.--------- 125 208

Travel locks, operation of- —_---_ — __--_--__-__--_---------- 20 3 1Traverse lock.___._-_---____________________---------- 19 29Traversing handwheel------..-..--.---------_----.-----__-- 1 9 2 9Traversing mechanism, run-in test.--.----.--------------.-.- 9 14Trouble shooting:

Battery circuit—— — — _._ — —- — — ---- — — — _- — —. — - 44 95Charging system... —-----_ — — -- — — -- —------------- 46 1 00Controlled differential______________________________ 5 4 1 1 3Cooling system._______________________________________ 49 1 1 1Electrical instruments.-..-__--_--------------.------_.. 47 1 03Engine. _________-_-_______ — — — ---._______.. 4 1 90Fuelsystem______--_-____-__-__---_--__----_-_---_. 50 111General--.---------.-----.-._._ — _.- — ___________ 4 1 90Ignition system._____________________________________ 43 9 5Lighting system—.- — ___-_ — — — — — -_--- — _- — — _ — — 45 97Propeller shafts..---------.--_— — — — — — — —_-_ 5 2 11 2Radio interference suppression_________________________ 4 8 107Tracks and suspension _________________________________ 55 1 1 4Transfer unit-. ...___ — — __-. — -__________ 5 3 1 1 3Transmission———— — — —-__ — — _- — - — — — — — — — -— 5 1 11 2

Valve, drain..... — — — ——— — — — --._.__-.__.----___ 160 255Vehicle:

Driving—— _- — _ —— — __--_ — __————————__. 1 5 2 6Operating controls—— — — — — — — — — --_ — - — - — — — — 1 0 1 5Starting (cold weather)___________--_-_-_-__---------. 24 4 0Stopping. ._-_-. ..-. ___....__ — — — ____------..- 1 6 27Submersion-__---.. ___________._.____.--_-_--_ 26 42Towing____-..-.-...-.--. — -. __--- --- --- — ----._ 1 8 2 8

Ventilating doors. — — — — — _____- — — — — — — — — — __- — — 11 20Ventilator controls-— — — — — — —— — — — — — —— — —— — — — 11 20

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TM 9-744 155 MM M41