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View picture in original size
Fig. 1

View picture in original size
Fig. 2

Zenith 18.5'''NVSI open face

stem wind and set
sub second

18.5''', Dm= 41.25mm, Do= 42.05mm
H= 5.25mm
(regulator +0.2mm)
F= 0.5mm
T= 2.0mm
15/16 jewels
f = 18000 A/h
power reserve 36h

Balance staff U1044

Stem W1543

1.60 x 0.95 / 0.25mm

Comments about the data

open face calibre (also made as hunter)
bimetallic screw balance
option: balance with 4 adjustment screws (example)
Breguet hairspring
cam disc regulator
negative stem mechanism for US market
in later samples click an regulator as illustrated for Zenith 16'''

Swiss Patent 27541:
design of the regulator
filed 01-19-1903, Hermann Roost, St-Imier (CH)
Swiss Patent 30751:
design of the stem mechanism
filed 05-19-1904, Georges Favre-Jacot & Cie., Locle (CH)

Example, year: signature; shock device
1912: 1166934, D+C (Dürrstein & Co.), Pat. Oct. 18, 1904 +30751, +27541

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.

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