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View picture in original size
Fig. 1

View picture in original size
Fig. 2

Junghans J31

stem wind and set
sub second

18.5''', Dm= 41.4mm, Do= 42.0mm
H= 6.0mm
F= 0.5mm
T= 2.5mm
1/3 jewels
f = 18000 A/h
power reserve 35h

Balance staff U418

Stem W300

Mainspring / battery
Zf3641, 2.20 x 16.0 x 0.20 x 460mm

1.85 x 1.15 / 0.25mm

Comments about the data

open face calibre
steel pallets, brass escape wheel

friction-fit balance staff, monometallic balance:
J31: 3/4 plate, flat hairspring
J32: 3/4 plate, Breguet hairspring
J33: bridges, Breguet hairspring, 15 jewels
J33a: bridges, Breguet hairspring, 7 jewels
J33b: like J33, production related differences
riveted balance staff, bimetallic balance:
J33c: bridges, Breguet hairspring
J34: like J33, production related differences
Ronda mentions for J31-J33 a friction-fit balance staff and a riveted, common is obviously friction fit.

Example, year: signature; shock device
1923: 0000821, Junghans

Not for Sale!
The movements presented in this caliber finder are not for sale. This is only a data sheet for identification and evaluation of the movement calibre, as well as for approximate dating.

bidfun-db 21.3 © 02-08-15, mtr-Ranfft

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