DIAL SIDE BULOVA MODELSTRAIN SIDE

12EBA12 EBAD12 ECAD

12 EBAC12 EBACD12 ECACD

SelfwindingandSelfwinding DateWatchesScale 1:1

SpecificationsMovement: Self-winding mechanism

Oscillating weight set in the movement. No additional heighttaken up by the self-winding mechanism. Oscillatingweight made of heavy antimagnetic alloy. Mechanicalinverser on roller bearings: no wear. Automatic engagingand disengaging of manual and automatic winding. Thusonly the operating gear turns, performance is improved andthere is no wear. Sliding pinion set between large jewels.

12'12'" lever escapement.Diameter of plate: 28.10 mm.Unbreakable mainspring.Beryllium balance.Self-compensating hairspring.19800 beats per hour.Incabloc.Angle of lift: 48°.

Designation of TypesCaliber Characteristics

Self-windinq (without sweep second)Self-winding, Calendar (without sweep second)Self-winding, Calendar (without sweep second), for flat dialSelf-winding, with sweep secondSelf-winding, Calendar, Sweep secondSelf-winding, Calendar, Sweep second, for flat dial

Total height of movement

2,85 mm3.30 mm3.30 mm3.15 mm3.60 mm3.60 mm

12 EBA12 EBAD12 ECAD12 EBAC12 EBACD12 ECACD

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Dismantling the watch

Removing the dial

After removing the screws at the side,the dial can be lifted easily. Werecommend removing all hands in orderto engage the cannon pinion (11 B)correctly, when re-assembling. A dialwasher must be inserted betweenthe hour wheel (7) and the dial, other-wise the hands will have too much play.

Checking the automatic gear

By moving the oscillating weight in bothdirections, make sure that the energyis being transmitted from the oscillatingweight (344) to the ratchet wheel (13).Should there be any irregularity,first examine the coupling wheel (313)and then the operation of the wig-wagpinion (312).

Releasing the mainspring

Remove the upper bridge of automaticdevice (341) and both wheels (309)and (313) as in fig. 1. By unscrewing theclick (32) and the rear screws of thewinding crown, you will be able torelease the mainspring.

Cleaning and lubricating escapeand balance

As shown in fig. 2, the balance and palletcan be easily dismantled withouthaving to disturb other parts of thewatch. The screws (39) of the palletbridge (216) and the minute workbridge (44 A) are identical andcoloured blue so that when dismantlingthe movement entirely, the correctscrews for replacement can be easilyidentified.

The barrel

Fig. 3 shows how easily the barrel isdismantled. The mainspring mustdevelop at least seven coils before thebrake spring slides off. It should beremembered that we use an unbreakablespring, and that the mainspring andbrake spring are linked tightly together.Factory lubrification is made in sucha way that periodical cleaning of thebarrel and mainspring is unnecessary.Bulova recommends not to dismantlethe barrel and in case of difficulty,replace the barrel complete (No.1 S).

Removing the oscillating weight

By taking out the two screws (302) as infig. 4 the bridge (301) of the oscillatingweight (344) can be separated fromthe plate. These components (301 and344) remain together since theoscillating weight is linked to the axleby a tight fit. The complete assemblymay be put into the machine forcleaning and, after careful drying, theupper bearing of the oscillating weightshould be oiled afresh.If, for some reason it is necessary toseparate the oscillating weight from theaxle and bridge, an auxiliary toolmust be made as in fig. 5. With a0.45 mm diameter punch, pressureis exerted on the axle and the tight fitloosened. Re-assembling may becarried out on a staking tool, but theoscillating weight must be replacedexactly at right angles to the axle.

Dial side of the movement

In this watch, the large driving wheelwith cannon pinion (4 F) is placedoff-center. The cannon pinion is clamped

2

2

onto the large driving wheel andholds the dial train, while the cannonpinion (11 B) in the centre of thewatch has a smooth bore and turnsfreely on the center pipe (106).A patented minute-wheel (8) fitted witha spring, ensures that there is noplay in the movement of the hands,see fig. 6.

Re-assembling andoiling the watchIt will be best to commence on the dialside with wheels 8, 29 and 30 A,lubricating the pivots (Cuypers BOZ).The minute work bridge (9) is thenreplaced. The cannon pinion on thelarge driving wheel (4 F) must alsobe lubricated. On the bridge side thetrain, the barrel bridge, the self-windingdevice, as well as the escapementand the balance are now replaced.Train, balance and self-winding deviceare then oiled (Synt-a-Lube).In doing so, see that the wig-wag pinion(312) and the nose of the stop-click(303) are not overlooked. The pivots ofthe stop-click (303) and the pallet(57) require no oil. Lubricate the palletstones (Moebius 941).

-....••.--.-•...•.~

3

5

Oil the barrel arbor (2) in the barrel,the plate and the barrel bridge(special Moebius lubricant). Thecomponents of the manual windingdevice must also be oiled. The

sliding face of the spring on the couplingwheel (313) must be lubricated(Glissalube red).Note: the name of oils and lubricantsgiven above are merely suggestions.Other brands of similar quality may alsobe used.

4

6

turn it around the axis of the handsin a vertical plane. The oscillatingweight will now wind up the mainspring,and it should drop under its ownweight. Malfunction may be caused byexcessive tension of the stop-click(303) or by other friction.

The calendarmechanism

Checking the windingperformance Its function

Wind up the mainspring six turns.Hold the watch as shown in fig. 7 and

by stop-plate. With the dial removed,the operating may be observedwithout difficulty. The date-indicatordriving wheel (574) fig. 9 is made up ofseveral parts riveted together. Theymust not be separated or lubricated.The date finger fitted on this wheelrevolves six times a day. Movingeccentrically, this finger engages thecog on the date-indicator only onceeach day. Thanks, however, to thisaccelerated rotating speed, it has beenpossible to reduce the date changingtime to some ten minutes. Moreover,the finger is fitted to the date wheel insuch a way that the date correctionoperates in one direction only.In reverse the finger passes the cogwithout engagement. This arrangementallows the date to be set manually

The components of the calendarmechan!sm are secured to the bridge

3

by simply moving the hands to and frobetween 11.20 p. m. and midnight.

Setting the date

When it is necessary to change the datemanually, simply turn the handsforward until the date changes, at about12 o'clock (midnight). If furthercorrection is necessary, turn the handsbackward to about 11.20 p. m. andthen forward until the date againchanges. Repeat this procedure untilthe desired date is reached.If time of day is before noon, continueto turn hands forward until correcttime is reached. If time of day is afternoon, turn hands forward 12.additionalhours before stopping at correct time.

Disassembly

1. Remove all hands, including hourhand, since in some models thehour wheel is locked to the movement.

2. Remove dial and dial washer.

3. Remove the two screws holding thedate indicator guard. Lift offguard, being careful not to let thedate jumper spring snap out of therecess and get lost.

4. Remove date jumper spring, dateindicator, date jumper, hour wheellocking plate (not used in all models),double hour wheel, date indicatordrive wheel assembly, and smalldate setting wheel.

5. Remove large date setting wheelscrew and wheel.

Assembly

Mount the intermediate date settingwheel and the setting wheel for dateindicator driving wheel (581 and 604).The latter is secured by the screw(601). Next, mount the date indicatordriving wheel (574). This must bedone so that the eccentric bore in thelarge brass wheel corresponds tothe slot in the upper brass plate, seefig. 10. When mounting the wheel,it should be positioned so that the boreand slot mentioned above are oppositethe bore provided in the plate. Todo this, you can use the method shownin fig. 11. When setting the double -toothed hour wheel (599) be careful notto alter the direction of the dateindicator driving wheel. Finally, insertthe date-indicator (576-1) the datejumper (596) and its spring (578) as wellas the hour wheel guard. Then fastenthe date indicator guard (571) by meansof the two screws (577).

7

8

Final check

Make sure that the bores in the bridgeand the date-indicator driving wheelare superimposed. Check also theforward and reserve movement of thiswheel. It must engage the dateindicator (576-1) to move the numbersprogressively. See that the datejumper (596) and its spring (578) movefreely.

Replacing the hands

Having replaced the dial, turn thewinding stem until the date "jumps".Then set the hands to midnight.

4

9

10

11

Sweep second

Assembly of the sweep secondmechanism

Fig. 8 shows the four additional partsfor this feature. Make sure that thetension of the friction spring for sweepsecond pinion (93) is exactly right. .The sweep second pinion must belubricated in the center pipe (106) andin the sweep second bridge (218)with Synt-a-Lube.

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lS 4F 5 68 7 8 9 119

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549 57 59 60 61 64 75c 10363 •• A

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104 106 113 114 134 301 303 307 308

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309 312 313 322 340 341 344

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37 38 39 40 41 42 44 44A 47

11302

1334

ft••48

t56

o 0W51

o58

T139

on107

T140

y33870l 70R 85A62A

12 EBAC Additional parts or parts varying from cal. 12 EBA

Scale 3:1

j (l .R e 'i'!'a;92 93 94A 322 344 90

65C

12 EBACD Additional parts or parts varying from cal. 12 EBA

11",.11.' .t 92 93 94A 101 106 322p5C

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8 9571

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L e t-...o 0574 578 581 596 599 604

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Scale 1:1 Scale 3:1

Scale 1:1 Scale 3:1

ow90

y577

T601

12 EBAD Additional parts or parts varying from cal. 12 EBA

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8 9 116 101 106 574 577

571

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Scale 1:1 Scale 3:1

12 ECACD Additional parts or parts varying from cal. 12 EBA

I J® j 1 @ L A8 9 92 93 94A 101 106 90

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65c

322 574

571

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o "--'596581 599 604

Scale 1:1 Scale 3:1

12 ECAD Additional parts or parts varying from cal. 12 EBA

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J. A@8 9 116 101 106

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604

••574 578 581 596 599

Scale 1:1 Scale 3:1

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W577

T601

if577

601

Printed in Switzerland BWC 1972