Tm 5-276 Ten Ton Trestle Bridge

7/30/2019 Tm 5-276 Ten Ton Trestle Bridge

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MANUAL

CTOBER1943

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icDomain,Google-digitized

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use#pd-google


2/65

GE

MENT,

.C, 11April1944.

3,ischangedasfollows:

UEa.(Superseded.)Oneunitpro-

ge or45feetof reinforcedbridge.Theprin-

nitarefour10-ton trestles,50trestlebalk,

onchess,and10-tontrestlebracing.(Seeapp.)

perseded)a.General.Oneunitof

etransportedby two2/-toncargotrucksand

lersortwo4-tonpontontrucksand two2-wheel

eeltrailer.Theprimemoveris either

argotruckwitha12-footloading bedora4-ton

t,3-inchloadingbed.The2%-tonshort heel-

ootloadingbed cannotbeusedsincetheover-

rferewith thetrailedload.

etwo-wheelpole-typetrailer,typeII,

rectangularframewitha drawbarofadjusta-

elescopic,permittingthreeadjustmentsin

horizontallywhenthetrailerisunhooked

hetrailer byclampingbeamsheldinposi-

crewsandchainlinks.Whenthetraileris not

msareheldinbracketsespeciallyprovidedfor

a sparetire,weighsabout2,300pounds.

d)a.General.The2/2-tontrucksarc

ras the4-tontrucks,andalltrailers areloaded

trailerloadprovidesequipmentforoneabut-

e-halftrestle spans.Thecombinedloadspro-

pletebridge75feet long(fivespans).

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wo-wheeltrailersee figure18andthefollow-

_ _

hoes

rimemoversee figure18andthefollowing

pacity

n

0-ton

0-ton

ton

o3-ton,two hoistsinchest__

nepickets

h

withchain

istsandshoes


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WaterTrestles.

2trestle.Becauseoftheshape oftheM2

thepinholes,itisdifficultto assemblebythe

)above.Twotrestlebalklyingone ontop

pendiculartothe shoreline.Twomore

acedapproximately12feetfromthe firstpair.

acrossthe balk(fig.21.1)andthetrestle

ection,thefourbalkmaybeusedin con-

an.

estlebalkandtransom{or assemblyofM2trestle.

hodofholdingtrestlecolumns.Atrestle

insteadofa ropelashingtoholdthe trestle

aligned.Theclampisplacedwiththehandle

rrapid loosening.(Seefig.27.1.)Whenthe

ofthehandleissufficientto releasethetrestle

e intothewater.


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dingtrestlecolumnwithtrestlebracingclampin erectionof


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EQUIPMENT

pacity..1

n6

6

0-ton._:32

0-ton30

2

ton6

o3-ton,twohoists inchestwithspare

nepickets__ 2

6

h16

withchain6

withouthoists4

TARYOF\\TAR:


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NICALMANUAL

CTOBER1943

MENTPRINTINGOFFICEWASHINGTON1943


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9October1943.

Bridge,ispublishedforthe information

ned.

TARYOFWAR:

2);R5(3);X.

lsseeFM21-6.)


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GE

graph

quired,5

PMENT

LOADINGS

ARATIONOFSITE

6


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DGE

NDINGSTAGES

ngstage 30

e32

ts33

nts34

DBRIDGEMAINTENANCE

,ANDSTORAGEOFEQUIPMENT

MENT54


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estlebridge(fig.1)is aportablefixed

ossinginfantrydivisionloadsoverdrygaps,

e bedofwhichisless than12feetbelow

dge

ebridgeconsistsof10-tontrestle balk

-tontrestles.Trestlebracingmakesthe


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hereareeight balkperspan,notinclud-

reinforcedbyaddingsixbalktoeachspan.

g.Clearwidthofthe roadwayis9feet

UEa.Oneunitprovides75feetof bridge,

principalcomponentsofoneunitarefour

tlebalk,eighty10-tonpontonchess,and

eapp.)

tockedingeneraldepotsforissue as

ofoperationscommander.

geusedasa fixedbridge.Postedand

enintableI.

ombinationwithfloatingbridge.

ridgegovern.Thesecapacitiesvarywith

M5-10.)

IMEREQUIRED.Underfavorablecon-

ruct75feetof 10-tontrestlebridgeinabout

ite.Darkness,tiredorinexperiencedper-

rconstructionsite,orenemyactivityin-

Asuggestedworkingpartyorganizationis


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How.

)

-

w..

r.

M1

A2

e

un,


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ENT

leMl.(1) The10-tontrestleM1(alu-

om,twocolumns,andtwo shoes.Two

d toadjusttheheightof thetransom.The

ainhoists,weighs750pounds.It is15feet

/zincheswide fromcentertocenterof

eadclearanceis12feet.(Seefig.2.)

etrestletransomM1 isabuilt-upalloy

g, 9incheswide,and15 inchesdeep.Asteel

pportstheendfittingsoftrestle balk.Metal

positionofthe8 pairsoftrestlebalkused

xtrabalk willfitineach intervalbetween

ximumof15pairs ofbalkperspancan be

Cleats areprovidedonthetransomfor

lk.

stlecolumnsM1 arealuminumalloy

er.Theyare insertedthroughwellsineach

dsecuredinplaceby pinschainedtoeach

ticalrowofholes,on33^-inchcenters,is

n.Twohorizontalpinholes,spaced 1^

dperpendiculartoeach otherthrougheach

.Eachend ofthetransomisheld inplace

oughoneofthe twoholesinthecolumn

mn.(Seefig.3.)A 3>-inchadjustmentin

nstertingthe pininanotherholeon the

holesinthetransom.A 1^-inchadjustment

lumnthrough90 andusingtheotherhole

mnpermitsattachmentofguy lines.Below

ngertowhichtheratchetchainhoist is


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ntransomandcolumn

stle shoeM1isa metalfooting24inches

bottomofeachtrestlecolumnbyaball-

freemovementoftheshoeaboutthe endof

tothe columnbytwohookschainedtothe

pairof holesinthecolumnandthe other

ofthecolumn.

)Two1^-to 3-tonratchetchainhoists

ghtofthetrestletransom.Thistype ofhoist

etrestleM1 andthetrestleM2,and sup-

lchainhoist.It hasa12-footchainwhich

ya singlestrandofchaintakesthe load

attwostrands ofchaintaketheload

with10-tontrestles,the single-chaincon-

ull effectivelengthof12feet.

chain hoistisattachedtotheswiveled

olumnM1,ortothe chain-hoistbracketonthe

ookto thestirrupatthe endoftransom

ofthetransomM2.Toadjust theheight

iston eachcolumn,removetransompins,

desired levelactuatingbothhoistsatthe

ndremovehoists.Thehoists arenot

yloadsof thebridge;therefore,theymust

d,withthetransompinsin place,before

ge.


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st,1^/2-to}-ton

eighsabout38 pounds.Twochainhoists

sin achest.Ratchetchainhoistsarealso

e anchorlines.

e 10-tontrestleMl(steel)is anall-

ral designanddimensionstothealuminum

e assembledtrestleisaboutthesameas

1.Thetrestleisdescribedonlyas itdiffers

g. 5.)

This transomconsistsofatubularsteel

heslong and19inchesdeep.Thetubeis

ereisno columnwellateachend;instead,

thetrestlecolumncanbeinsertedfromthe

epthejawsofthis openingtogether.

somarethreesetsof pinholes,andtwo

m.Toone pin,insertedintheoutermostset

helowerendoftheratchetchainhoist. The

ughone ortheotherofthe tworemaining

oneoftheholesin thetrestlecolumn,thus

ecolumn.Thelattertwo setsofholesare

rtically,and,sincetheholesonthe trestle

hesapart,a1^-inchadjustmentcanbe

verticalrowof holesinthecolumnM2

olumn.Theswiveledhangerontopofthe

placeis substitutedadetachablechain-

escribedbelow.

hoeismadeofsteeland is27inchessquare.


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2


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n-hoistsupportingbracket

bracket.Adetachablechain-hoistsup-

neendofeachratchetchainhoist,used to

estletransom.Thebracketisheldin place

ertedthroughoneofthe holesinthetrestle

hedtotheend ofthepinlocksit inplace.


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butmentsill,andtrestlebalk

ntrestlebalk(fig.7)areused asstringers

.Abalk,whichismadeofwood,is 4by6

s,and weighsabout100pounds.Metal

erthetubeonthe topofthetrestle transom.

sedtolashthebalk tothetransomandpro-

ng.

chess(fig.7)areused tofloorthebridge.

sn^byi]/zinchesby 12feet,andweighs

ateachendtopermitinsertionof siderail

chessareprovidedtofillin smallspacesin

ertransoms.

tonpontonabutmentsills(fig.7)aremade

hesby13feet,andweigh135 pounds.They

eringsattheir ends.Scoremarksoneach

epositionsofbalk.Thesill isstakedinplace

kareusedforsiderails.Theyare placed

yabovetheoutsidebalk.

n-tonpontonsiderailclampsareusedto

ngageundertheoutsidebalk andabove

hessinplacebetweenthem(fig. 8).Aclamp


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estlebracingsteadiestrestlespanscrossed

racingpartsareasfollows:

s a22-footsectionof2^-inchstandard

-inchandone 1^-inch,drilledateachend.

teningthestrutshoe.Apicketis inserted

screwtheassembledstrutandstrutshoe

Abracingstrutweighs125 pounds.(See

eusedonlyforbracing;otheruses orrough

rdamageit.


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oeand.strut-shoepinassembly

shoe(fig.10)is attachedtothebracing

ytoscrewthestrutintothe ground.Theshoe

oitmaybescrewedinto softearth(fig.34).

y.Thestrut-shoepin(fig.10) fastens

utshoe.Throughoneendof thepinisa

p. Topreventlossofthepin assemblywhen

fromthestrut,thestrut-shoepinshould be

withthelatchandboatsnap insertedintheir

.Thisclamp(fig.n)fastensthebracing

n(fig.12)orto theanchorpost(fig.33).It

lampsconnectedbyaswiveljoint.The

s fastenedtothebracingstrut,andthe

mnortotheanchorpost.Theclampweighs


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ost

sts(fig.13)anchortheend trestle,

stoo hardforstrutshoes.The postisa

pipe4^inchesin diameter(sameasthe

ralflangeat oneend.Theotherendhas a

gapicketusedto screwthepostintoa hole.

to theanchorpostwithacolumn-bracing

waysshouldbeanchoredsecurelytohold-

r,6-inchcapacity

apacity.Thisauger(fig.14)is used

eanchorpostis set.Itis5 feetlongand

ninepickets.Thisprefabricatedhold-

estle-shoeanchorcableonthe shore,when

vailable.Itconsistsof ametalplatewith

.Eachpicketis 1^4inchesindiameterand

le atoneendforeasy removal.Theentire

s,andeachpicketweighs15pounds.


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ickets

ope.Thisgrip,(orcome-along)(fig.16)

etchainhoisttothetrestle-shoeanchor

Twogrips usuallyarerequiredforthis;one

efreeendof thecableendsinan eye.

wire rofe

eused

rope

s

ch

p

nding

rerope


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OADINGS

eneral.Oneunitofa 10-tontrestle

rtedontwotwo-wheel,pole-typetrailers

trucks.(Seefig.18.)

etwo-wheelpole-typetrailerwith

angularframewithadrawbarof adjustable

scopic,permittingthreeadjustmentsin

orizontallywhenthetrailerisunhooked

hetra1ler byclamp1ngbeamsheld1n

edscrewsandchainlinks.Whenthetrailer

beamsareheld inbracketsespeciallypro-

a sparetire,weighsabout2,300pounds.

eeltrailer.Thisisa 4-tonponton

oadingbed,whichwillaccommodate

eightofproperlyloadedvehiclesisas

s

s

Thetwotruckandtrailerloads are

truckandtrailerloadprovidesequipment

one andone-halftrestlespans.Thecom-

mentforacompletebridge75 feetlong


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wheeltrailer(seefig.18).

LTRAILERLOAD

pontontruck(seefig. 18).

NTONTRUCKLOAD

apacity

st,1^-to3~ton

0-ton

-to3-ton....


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TION

eis selectedtomeetbothtechnicaland

rtacticalrequirementsseeFM5-6.

ENTS.Thefollowingtechnicalcharacter-

esshouldpermitquickconstructionof

sonbothsidesof thegap.

firm,tosupportthe abutmentsilland

sts.Theyshouldnot besohighor steepas

ngfortheapproach,norso lowthatnormal

erflowthesiteorunnecessarilyincreasethe

o supporttrestles.Ifthegapis water-

rexaminationoftheareatobe occupiedby

othat obstructionssuchasstumpsandsnags

rnaturalholdfastsshouldbe present

trestle-shoeanchorcables.

Ea.Theapproachroadshouldbecon-

epreparedand clearedpriortoarrivalof

adjustedtofittheterrain.The abut-

orthe abutment,forunloadingtrucksand

quipment.Wherestackingspaceisnotavail-

emaybebuiltdirectlyfromthe trucksand


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GE

onbridgeconstructionisdescribedwithout

ofpersonnel.Asuggestedorganizationofper-

sofeachworkingsection,isgivenin sec-

eis constructedfromthenearbankby

bankabutments,(1)Centeringand

edrivenon thecenterlineofthe bridge,

sillandtheother about20feetfartherfrom

far-banksideofthesill islaidagainstthe

secondstaketotheendsof thesillare

shing.The sillissquaredwhenits middle

bridgeandthese twodistancesareequal.

ngandsquaring,theoutline ofthesillis

guideinexcavation.

entsill


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s leveledforthesill,allowingspacefor

nofabutment-spanbalkonthe near-bank

xedinplaceby11pickets,9 onthesideof

betweenscoremarks,and2ontheside away

endsofthesill.

abutment-spanbalkareinposition on

cedon edgeagainsttheendsofthe balk,

heflooring.Thischessisthe enddam.Itis

wopicketsneareachend.Roadmetalis

heend damto1inchabovethe flooring.

efar-bankabutmentisconstructedas

edeterminedaftererectionofthefar-bank

rosseswater,materialsforthe farabut-

bankontheraftused toerectdeep-water

watertrestles.Therearetwomethods

ertrestle:

ruts,(a)Assembly:Thetrestleis assem-

ts finalpositionaspossiblewithoutinter-

eabutmentsill. Thetransomisplacedon

ebalk,lyingoneon topoftheotherin the

umnsareinsertedinthetransomand held

lowestsetofholesin thecolumnthatthe

ootingsallows.Trestleshoesareattachedto

fastenedbyhookschainedtotheshoes.

the shoessothattheycanbe anchoredto

pedientfootingsforincreasingthebearing

pared.(Seepar.21.)Ratchetchainhoistsare

oistend hookedtothetransomstirrup.

to thetopofeachcolumnbya column

snuglybutleftjust freeenoughtopermit

n,inordertopreventshearing theconnec-

serected.(Seefig.21.)

edtrestleisraisedand manhandledinto

utmentsillisproperlyembeddedandseats

repared.Threemenraiseeachcolumn,and

gstrutto guidethetrestleintoa vertical

etrestleis spacedattheproperdistance

acingthe outerbalkinposition.Thenit

plumband centeredonthecenterlineof

lk thenaredeliveredandplaced,andthe

ed.


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cingstruts

(a) Assembly.Thetrestleisassembled

struts. Two^-inchropeguylines,about

byclovehitchesattheirmiddlepoints to

etrestlecolumns.(Seefig.22.)

estle,threemen raiseeachcolumnand

ofthe guylines,whichsteadiesandplumbs


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raisedandmanhandledintofinal position.

afterthetrestlebalkhavebeenplacedin

tle-bracingstrutsarefastenedtothe top

stle iserected,picketsbeingplacedthrough

nstoformladderrungsforclimbing.(See

ines


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ep-watertrestlesareassembledand

aftconstructedof10-tonpontons(fig.24)

24).Eitherbracingstruts orguylines

trestleasitis raisedtoposition.

ctdeep-watertrestles


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stlesassembledonraft


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etrestletransomis placedonitssideon

wardfromtheraft.Trestlecolumnsare

htheir upperendsriverwardandwith

nsproject1ngshorewardbeyondthebottom

portionsof thecolumnsrestacrossabalk

Trestleshoes areattachedtothecolumns.

ted,but thecolumnsarefastenedtothe

stiedtothe shoesandtransomstirrupsas

ngthelashing atthestirrupafterthe trestle

sesthe columnstoslidethroughthetransom

opintotheirseatings.Anchorcablesof

uldbeattachedto theshoessothatthey

sts.

atertrestle

ntheraft withtrestleassemblyreaches

gethetrestleis raised,guylinesorbracing

and plumbthetrestle.Outsidetrestlebalk

e.Theraftismanouvereduntilthe centerof

terlineofthebridge.Thenthe officerin

olumnsdropped(fig.27).Chainhoists are

omisraisedclearof theraft,andtransom

racingis installedanddeckinglaid.The

kup anothertrestle.


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atertrestleContinued

odofincreasingbearingareaoftrestle shoes


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Underrepeatedcrossingsofheavyloads,

yriver bedssettleexcessively.Trestlecol-

ttlesappreciablymorethantheother.Figures

ofexpedientfootingsusedtoincreasebearing

hesespreadfootingsare lashedtothetrestle

trestle.Panelsofsteelgratingor airplane

rthefootings,helppreventthemfromsl1pp1ng

msetvert1cally,w1thp1ns1nthelowest

gs orplanksunderthetransom,likemud

1ngand w1lladdr1g1d1tytothe columns.

ulttomove,however.Evenwiththe aidof

willneedcontinuousmaintenance.(Seesec.

ebridgesite,and properpreparationand

footings,willreducemaintenance.

dientmethodofincreasingbearingareaoftrestleshoes

Conditionsinfluencingtypeofinstalla-

cingused dependsmainlyuponstability

ns,wheresettlementofindividualtrestles

tomakeanintegralunit ofeachtrestleand

twobracingstrutsfromthe topofeach

dat thesides.Thisis calledtripodbracing.


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unstablefoundations

ons,wherelittlesettlementisprobable,

ectedwithsinglediagonalbracing.(See

djacenttrestlesareconnectedwithdouble

32.)Wherefouror moretrestlesareused,

aced,eachpairof trestlesthusforming


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emistablefoundation.

mis nearthetopofthe trestlecolumns,

ssarytoprovidelateralstability.Onan unstable

diagonalstrutbetweencolumnsunderthe

ablefoundations,itconsistsof twotransverse

)(fig.31).


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stablefoundation

heend trestleonanytypeoffounda-

orebybracingstrutsfromthetop oftheend

postsinholes,dug withthepost-holeauger,

ach.Eachbracingstrutisfastenedtothe

dby acolumn-bracingclamp.Theanchor

ecurelytoholdfasts(fig.33).

nstheendtrestlei sfurtherbracedina

secondbracingstrut fromthetopofeach

gsidethebridge.(See fig.30.)


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e

estles,(1)Unstablefoundation.Nor-

omakethetrestle anditsbracingactasa

etopofeachcolumnmaybe usedon

0.)Thetripod-bracingstrutsform anangle

nterlineofthebridge.The firststepisassem-

dstrutshoe.Thestrut-shoeshankis inserted

gstrutandfastenedwiththe strut-shoepin.

ofthebracingstrut thenisplacedatthe

esoil,andtheupper endofthebracing

estlecolumntodeterminewherethecolumn-

enedto thecolumn.Acolumn-bracingclamp

umn,andthe strutportionofthe clampis

ebracingstrut.Thispermitsthe clampto

twhilethestrut isturnedbya steelpicket

eend.Thestrutshoe isscrewedintothe

rmfooting.(Seefig.34.)Thecolumnand*

andtightenedalternatelytoobtaina firm

andstrut.Finally,thecolumn-bracingclamps

racingstrut.Underno circumstancesshould

weenadjacenttrestlesifthere isapossibility

rethan Ifoot.

.Useonelongitudinaldiagonalbracing

31.)

ongitudinalcrossbracing.Bothendsof

dontheoutside,and bothendsofthesecond

columns.(Seefig.32.)


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gstrutshoeintoground

ble,(1)Shoesofendtrestlesare pre-

steningthemwithwirerope toanchorposts

hen siteconditionsrequire,alltrestleshoes

eshouldbe used;itstretcheslessthan

htenedwiththe ratchetchainhoistand

ble,passone endofthewirerope

hetrestleshoe,andfastenthe freeendto

eusingatleast threeclips,spacedabout

er endofthecablearoundthe holdfastor

achedtotheholdfast,placeonecablegrip

nthestandingpartof thecable,andconnect

hetchainhoist.Fastenlooselythreecable

position.Tightencablewithratchetchain

Removeratchetchainhoistandcablegrips.

racing.SeesectionVIII.

ormalconstruction.Inthenormalbridge

pan,notincludingsiderails.Theoutsidebalk

thecleatsoneachtransom.(Seefig.36.)

sidebalkare laidfirst,tospacethetrestle

eis inpositiontheremainingbalkare laid.


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e-shoeanchorcable

ctedbyraftit maybenecessarytoslideout

gbalkalreadyin place,topersonnelonthe

ofthebalkonthe transom.

balktotransom


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on.Inthereinforcedbridgethereare14

gsiderails,the 6pairsofextrabalk being

the balkofthenormalbridge(centerspace

ssper span.Half-chessareusedtofill

ovetrestle transoms.Chessareplacedwith

ndalinedalongtheline betweenoutsidepairs

dto within1footofthe lasttrestle,to

ofthe lastspanofbalk.Twomenlay chess,

balkandreceivingchessdeliveredbycarriers

hinsingle fileontheright-handside ofthe

acedandclampedonebaybehind the

ilclampspersiderailare placed,withscrew

sofeachspan.(See fig.38.)


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amps


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llowingtablegivesasuggestedorgani-

constructthe10-tontrestlebridge.For

ileddutiesof sections,seeparagraphs25

but-

nd

st

y

ten

al-

-

uc-

rry

dshal-

hird

rect

stle.3

n

quip-

atertrestle,sectionimmediatelystartsassemblingtrestlesonraft.

p-watertrestle,sectionassemblesitonraft.

workassistinerectingtrestlebracing.

5feet,menmust beaddedtocarryingsection.


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NCO,6men)

butments.

esand bracing.

es.

ndfastensiderail

bleclips(for

ofbridge,andlevel

nplace(9 on

eachendof

areinplace,set

ewithtopflush

ketstoholdin

near-bankface).

ptolevelofI inch

e.

stle-shoeanchor

inerectionof

es.

bankabutment,

g,sectioncar-

estlebalk) and

tilpositionof

rmined.Re-

ledaftercom-

ent.


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ON(1NCO,10men)

allow-watertrestle

edingtrestlesand

onraft.

succeeding

g ferried.

hainhoists,

ed).

etrestleon).

).

ngs).

stles:

ainhoistsandguy

(loadedonraft):

hain

).

n

erec-

etrestle

ngs).

2trestlebalk,in-

s,attachchain

es (orbracing

te:Ifbracing

pto snugfit,but

umnto pre-

boltduringerec-

es(or bracing

of bridge.

m.

agehoists.

tles:

ime)onraft.

trestlesarebeing

equipmentonraft

dtrestles:

atertrestle,sectionimmediatelystartsassemblingtrestlesonraft.


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1NCO,14men)

restlesandfar-

tle,succeeding

tmentequip-

hess(NCOand

s,andside-

s(1

but first

span.

ffounda-

d14men):

restlesandfar-

t(seepar.20).

nd8men):

balkon transomsof

y(secondtrestle

p-watertrestles).

e.

ss guylinesto

dge.

estleupright.

next trestle,or

ainingdeep-water

ffar-bankshal-

-abutment


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NGSTAGES

singpneumaticor10-tonpontonraftsa

ftdirectlyfromthebanksusuallycanbe

lesstimethanit takestoconstructalanding

otbepreparedwithabulldozer,or where

bulldozerisavailable,alandingstage is

ng-typelandingstagesufficesforlight

g10-tontrestlesis preferred,andmustbe

YPELANDINGSTAGEa.Multiple-span

stage(fig.39) isbuiltwitha hingespan

s. Theriverwardendofthehingespan is

edso thatthebalkprotrude6 to7feet

esno liveload;itis usedonlytoraiseand

ndingstage;loading


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balkis securedtothetransombya detach-

Shorewardendsofbalkareattachedinthe

somofthe adjacenttrestle.Thenumberand

andingstagematchthoseofthe rafts.Chess

thehingespaninthe usualmanner.Two

oneachsiderailon theshorewardsideofthe

uylinesor trestlebracing(fig.39)maybe

position.Chainhoistsareused toraiseand

ge.Wheredeepwateriswithin 15

restlespansmaybeeliminatedanda single

ctlyontheabutmentsill maybeused.If

feetoftheshore,trestlebalk maybeused;

ustbesubstitutedfortrestlebalk.(See fig.40.)

dingstage;unloading

FTa.Balkonthe raftshouldnotpro-

r enoughtoallowthetrestlebalk ofthe

eriverwardgunwale(orfloat sill)ofthe

eeboardoftheshorewardpontonor float

eraftmaybe savedbysupportingtheriver-

anonahingesill placedontheshoresideof

floatsill).A trestlebalkmaybeusedas a

raft(fig.41).

areusedunderthedeckof theraft,

eninterlockingbalkmakesitdifficultto


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INGSTAGE.Whentheraftapproaches,

ghto allowtheshorewardendofthe raft

aththeoverhangingportionofthe hinge

somislowereduntilthe hinge-spanbalk

on.Hooksofthe chainhoistsaredisengaged

desfreeonthe columnsastheloadmoves

isloaded,chainhoistsareengagedand

ermithinge-spanbalktocleartheraft, which

NFORRAFTLANDING

NCOLUMNS

ADINGANDUNLOADINGRAFT

ANDINTERLOCKINGBALK

dingstage


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ADINGRAFTS.Theapproachingraftis

ldin placebyguylinesto theshorefrom

dandri verwardpontons.Whilevehiclesare

guylinesareanchoredtosuitableholdfasts.

maysupplementguylines.

UIREMENTSa.Thehingespan ofthe

edinabout 20minutesbyexperiencedper-

ckedatthesite.Onenoncommissioned

uiredas aworkingparty.

ditiontothecrewoperatingtheferry,

nhoists andguylines.

oadedat thelandingstageinabout


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geguardnormallyisprovided.Its duties

chforfloatingminesandotherobjects

.

ridge.

ecessity.Trafficcontrolinsuresprompt

calvehicles,divertsvehiclesthataretoo

spacingofvehicles,andotherwiseexpedites

reventsdamagetothebridge.

ehiclesarenotpermittedtoblockroads.

ersectionsofapproachroadswithmainroad

vehiclesthatcannotcrossthebridge,and

lmentforvehicleswaitingtocross.While

rsareinstructedasto speedandvehicle

ebridge.

epostedateachend ofthebridgeand

onalguardsareplacedatintervals onlong

bridgeguardmust knowthesafe

etableI.)Load limitsshouldbeexceeded

nallconcernedknowtherisk,and underthe

estindicatedbya recordofprevious

erlyplaced,andtight.

gcautionspeed(seeebelow).

edforcrossingwithcaution(see/below).


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enthe 10-tontrestlebridgeisused

shouldnot exceedthefollowingspeeds:

able I),25milesper hourforlight

for heavyvehicles.

tion(tableI), 5milesperhour.

combinationwithafloatingbridge,

thespeedsestablishedforfloatingbridges.

18inches.If clearanceofwheelsortracks

chsideofthe vehicle,speedmustbereduced,

n 3inches,thevehicleshouldbeguided

minimumintervalbetweenvehicleson

east50yardsmust bemaintainedbetween

tion.

Ea.Spareparts.Asmallsupplyofspare

tlebracing,andothermaterialsforrepair

neabutmentforimmediateuse.Alarger

undercoverandconcealmentinthe

eshouldbe inspectedfrequentlyfor

ouldbetightenedperiodically.

einitialsettlementoftrestles,and

geisin use,column-bracingclampsshould

edtoreleasestressesintroducedin thebrac-

stles.

uldbeadjustedtoallowfor smallsettle-

blesettlement,thetrestlemustbe raised

onarebuiltfoundationandnewfootings.


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ND

eral.Aregularprogramofinspection,

epair,andpaintingshouldbesetupandfol-

sstoredafterextendeduseit isespecially

take correctivemeasures.

ouldbethoroughlycleanedbeforebeing

eriod.Metalpartsshouldbe keptcleaned

reducerusting.Chainhoists inparticular

ventexcessivewearanddamageto the

mechanicaldevicesaredesignedto

outlubrication.Screwpartsparticularly

ecausethisleadsto accumulationofdirt

cessivefoulinganddamageto screwparts.

nhoistsshouldfollowthemanufacturer's

okeeptrestlesandwoodenpartsthor-

39^fordetails.)

s,andsills.Ingeneral,repairs tothese

ngcrushedor splinteredwood,reshaping,

emishes,andstra1ghteningandrefastening

ouldberemovedfromcondemnedtimbers

placements.Minordamagesthroughcutsor

subjecttodecay,andshouldbetrimmed

acticable.

iderail clampsandsimilarfittingscon-

mationsofmetalpartsand removingburs

he transomandcolumnsofatrestle

field.Minor puncturesanddamagetothe


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62/65

epairedwitha 10-tonpontonrepairkitand

eweldingandcuttingset.Otherrepairsgen-

depot.

uipmentmustbekeptpaintedto pre-

rotting.Thisis particularlynecessarywhen

open,orusedinsalty orbrackishwater.

Paint,olivedrab,lusterless,marked

coat.Thisis ahighlywater-resistant

materials.Useonlyforrefinishingwater-

marked"PaintF-I."Containscritical

aintingsteelandaluminumwater-immersi-

ed"PaintF-II."Useforrepainting

"Paintcleanerandthinner."Useas

r.Furnishedin50-gallondrums.

t,marked"PaintetcherH3P04."Etch-

minumalloyequipment.Furnishedin

ourpartsofwaterwithone partofpaint

oveoldpaint.

ndsteeltrestles.Removelooseandcracked

tterfromall surfaceswithwirebrush.Clean

entisavailable.Removesandfromsurfaces

dditiontosuch cleaning,washsurfaceswith

erandthinner),andrinse inclean,unused,

aluminumsurfaceswithphosphoricacid

her),keepingsolutionincontactwithalu-

tes;thenwashthesurfacethoroughlywith

atsofprimer(PaintF-I)to thetrestle

yonefinishcoatof paint(PaintA)24hours

,andotherwoodenparts.Cleanallloose

foreignmatteroff surfacestobepainted,

ocoatsofprimer (PaintF-II).Applyone

rs afterpriming.

ces.Brass,bronze,andothernonferrous

uminum)neednotbepainted,butshouldbe

ereflectionoflight.

yprimerwithin5hours aftercompletion

rovideasmooth,evensurface,suitablefor

ofsubsequentcoats.Applybybrushorspray.

on ofpaintwithaquart ofmineralspirits

.Donotapply painttomoistsurfaces,nor


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sspartis protectedagainsteffectsof

ove50 F.theatmosphereincontactwith

ouldbeat approximatelythesametempera-

chitisapplied.Whenpaintinghas com-

eration,includingprimingcoatsandfinish

dassoonaspracticableallowing,however,

nprimingandfinishcoats.

Alwaysstoreequipmentundercover,

nstorage,disposeequipmentsothatwater

entilationis adequate,andnoneofthe

ound.Equipmentmustbewellpaintedwhen

xtendedperiod.

aybestored inanyconvenientfashion,

eventcrushng orbendingofcolumnsand

transomshouldbeplacederect,toavoid

magetocleats.Trestleshoes maybe

e,teethdown,columnsalsolaidsideby side.

eyalwaysshouldbestoredin chests.

esemembersshouldbeplacedin well-

heground,withoneend higherthanthe

if intheopen.

re suitableforstoringandtransporting

mallmetalparts.

eseincluderopeandsteelpickets.Rope

andstoredasprescribedin engineerfield

dbeforestorage,itshouldbewashedthor-

dirt.


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apacity1

type6

n6

et2

0-ton32

0-ton36

pacity40

capacity2

-to3-ton4

nepickets2

,clamp6

nch32

withouthoists4

,transom4


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CTION(1NCO,10men)

tsecondshallow-

gtrestlesfromraft.

sttrestle.

teven-

stle:

ertrestle(par.

tles:

dtrestles

stle:^

dinsamemanner

tles:

bridgeNCOand

g6 menstay

on(4 trestlemen

rryingparty).

es.(2 raftmenon

nearlines.)

raftandengage

euntilbalken-

yerectedtrestle.

of bridgeby

en).

ining6 balk.

ttransomfree of

sconnectchain

ounload,or

m.

asnexttrestleis

stlesareun-

edinsame man-

watertrestles.

26).

p-watertrestle,sectionassemblesitonraft.

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Documents

Tm 5-276 Ten Ton Trestle Bridge