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View picture in original size
Fig. 1

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Fig. 2

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Fig. 3

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Fig. 4

View picture in original size
Fig. 5

Junghans 628.00 (628)

timer, 1s (0.1s), 60s, 60min, pillar wheel
stem wind
sub dials for 1/10 seconds, seconds, minutes
stop over wheel on escape-wheel arbor (1/10 seconds)
in early samples additional balance brake

19.5''', Dm= 43.6mm, Do= 48.8mm
(Dm: bridges, Do: base plate)
H= 7.1mm
(stop mechanism and 1/10s cock +1.15mm)
F= 1.7mm
(thickness base plate)
T= 2.4mm
7 jewels
f = 36000 A/h
power-reserve 3h

Balance staff U2340

Stem W1819 / W1890 / W1891
(standard / plastic case / waterprotected)

Mainspring / battery
1.65 x 15.5 x 0.21mm

/ 1.20 x 1.20 x 0.26mm

Comments about the data

open face calibre
winding gear with rocker on back side
barrel with Geneva stopwork (3 revolutions)

The function differs from the common (Fig.3-5):
The escape-wheel arbor carries a wheel D with 30 teeth, 3 of them longer than the other 27.
When starting (Fig.3) the lever B jumps to the left, and a spring at its end applies a defined start pulse to the balance. Moreover the balance is released by lifting off the brake spring A. Simultaneously lever C is moved to the left to release wheel D, thus to start the watch.
For stopping (Fig.4) only lever C is moved to the right, and stops wheel D.
For resetting (Fig.5) the lever C is moved to the left, only so far that the watch runs until one of the long teeth touches the end of the lever. Thus the watch is stopped, if one of the three hands on the escape-wheel arbor reaches zero on the 0.1s scale. Simultaneously lever B releases spring A, and this damps the oscillation of the balance.
The only noticable benefit of spring A and lever B is that the balance starts from its rest position with a defined pulse, even if the watch is started very soon after a reset. As this benefit is fairly unimportant, this assembly was left out in later or more basic samples (cf. Fig.2).

628.70: 0.1s, 7 jewels
628.71: 0.01s, 15 jewels
628.72: 0.1s, 7 jewels, addition timer
628.73: 0.1s, 15 jewels
new base plate, minor modifications:
628.00: 0.1s, 7 jewels
628.01: 0.1s, 15 jewels
628.02: 0.1s, 7 jewels, addition timer
628.11: 0.01s, 15 jewels
628.20: 0.1s, 7 jewels, split second (rattrapante)

Example, year: signature; shock device
1-2) 1977: G77, Junghans, 628, Gebr. Junghans, Made in Germany, 7 Jewels, Unadjusted; Junghans-I
3-5) 1969: D9, Junghans, 628/01; Junghans-I
(Junghans 628.01)

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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