The Elgin Grade 760, 761 Service Bulletin
This information is from an Elgin service bulletin mailed
out to watchmakers in 1960 as an update for their Elgin manuals.
It covers the new 760 and 761 grade automatic wristwatch products.
Do you have a vintage Elgin watch to be serviced?
6.81 Grades 760, 761
Elgin grades 760 and 761 are self-winding movements, 6/0 size. Grade 760 has 30 working jewels, 761 has 27 working jewels. Both grades have 360 degree rotors that wind in either direction. Both grades have DuraBalance and DuraPower mainsprings. Grade 760 has a "beat-adjusting" device that will enable the watchmaker to place the watch in beat easier. This is covered in detail under primary number 22.0.
The 6/0 self-winding movement is unique in design. The following features should be noted:
Driving gear A and gear assembly B (Figures 2 and 3) contain three thin, round jewels. These jewels move freely in tapered elongated slots. The slots in gear A are opposite in direction to those of gear assembly B. As the rotor moves in a counter-clockwise direction, the jewels in gear A bind between the side wall of the gear slot and the hub. This action winds the mainspring through the selfwinding train. Gear assembly B will idle. When the rotor reverses direction, gear assembly B will wind and gear A will idle.
The self-winding train has two different winding ratios. When the mainspring is nearly unwound, the rotor winds quickly in both directions. With the mainspring nearly full-wound, the rotor turns freely in only one direction, and mayor may not turn under its own weight in the other direction. This action should not be misinterpreted as a faulty condition if noted during servicing.
The rotor assembly is a single unit. It does not require disassembly during service. Because of the necessity for special tools and techniques, it is recommended that the watchmaker not attempt to service the rotor assembly. If a replacement part is ever needed for the rotor because of wear, the entire unit should be sent to your nearest Authorized Elgin Material Distributor for exchange. Your distributor will exchange the worn rotor with a refurbished rotor at a nominal cost. Or, if you want a completely new rotor, your distributor will supply it to you at a slightly higher cost. Separate parts for the rotor are not available.
Exploded View of Movement
(2) Rotor retainer clamp
(3) Flanged rotor stud
(4) Rotor assembly
(6) Barrel bridge
(7) Rotor idler pinion
(8) First automatic winding wheel
(9) Second automatic winding wheel
(11) Ratchet wheel
(12) Idler ratchet wheel clamp screw
(13) Idler wheel ratchet clamp
(14) Ratchet idler wheel
(15) Train bridge
(16) Center wheel
(17) Hand driver wheel
(18) Minute wheel clamp and setting lever spring
6.81 To Disassemble for Servicinga) Remove hands, dial, hour wheel and cannon pinion from movement.
b) Remove rotor retainer clamp screw (1) and rotor retainer
clamp (2). When screw is removed, push clamp away from flanged rotor stud (3) and remove with tweezers.
c) Remove rotor assembly (4) with tweezers or invert movement and allow rotor to fall free. NOTE: To clean rotor assembly see paragraph 6.92.
d) Let down mainspring slowly in normal manner. Note: It is impossible to let down mainspring with rotor attached.
m) Remove minute wheel clamp and setting lever spring assembly (18), also minute wheel.
n) Remove rocker plate assembly, winding and setting wheel (19)
and washer (20).
o) Remove stem (24) and bevel pinion (25).
p) Remove center bridge (26) and third wheel (27).
q) Remove sweep second pinion (28) (see figure 7).
6.82 To Reassemble, reverse the disassembly procedure.
6.9 To Service Elgin Grades 760 and 761.
This movement being disassembled according to procedures in paragraph 6.8, care should be exercised to lubricate only certain parts and to check certain points as given in paragraphs 6.91 and 6.92 before reassembling.
6.91 To Lubricate (see figure 4 for points of lubrication)
Proceed in the conventional manner, except that these points should be carefully observed:
a) Do not disassemble the barrel. The mainspring is permanently lubricated. To service, merely brush the barrel teeth and re-oil the barrel arbor pivots with Elgin M-56B.
b) Lubricate with Elgin M-56B:
c) Lubricate with heavy oil or light grease such as Vaseline:
d) Do not lubricate:
6.92 Clean rotor assembly in conventional manner without disassembly. Rotor should be thoroughly dried after cleaning.
6.93 Check Points
When servicing, check the following points:
a) Spring tension on click (5) should not exert excessive pressure on first automatic winding wheel.
b) Rotor gears should move freely in opposing directions.
c) Case screws should be tight to avoid their working loose to interfere with rotor rotation.
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