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View picture in original size
Fig. 1

View picture in original size
Fig. 2

Alpina 831A

manual wind

5.75 x 8.5''', Dm= 12.8 x 19.2mm
Do= 12.8 x 19.5mm
H= 3.4mm
F= 0.5mm
T= 1.5mm
15 jewels
f = 18000 A/h

Balance staff U2428

Stem W97

1.20 x 0.60mm

Comments about the data

bimetallic screw balance
differences not known between 831, 831A

Swiss Patent 158882:
lever for secure fixing of the stem in the movement, as long as it is in the case shell (cf. Alpina 490A)
filed 11-21-1931, Straub & Co. Fabriques des Montres Alpina (CH)

Example, year: signature; shock device
ca. 1940: Alpina 831A - 1818, Pat. +158882

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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