Junghans J31, updated 24.12.2019 - Helicopters, pocket watches, flight simulation, tools.

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Junghans J31, updated 24.12.2019

Junghans
Indestructible Watch
1923
Open face
J31
102
18,5'''
42,0 mm
41,4 mm
6,8 mm
18000 A/h
40 h
U418
W300
Zf3641
Junghans mentions spring #1007
450 x 2,25 x 0,205 mm
F.W.S 1942 page 17
3
Kind:
Production:
Type:
Variants:
Catalog Group:
Size:
Outer Diameter:
Nominal Diameter:
Height:
f:
Power reserve:
Balance staff:
Stem:
Mainspring:


Reference picture:
Jewels:
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Here are some hints how to separate some Junghans movements from themselfs.

Is it a J26 or a J31/J32?
As you can find J26, J31 and J32 movements without markings and as they look the same, there is this little hint, which can help you to determine if you have a J26 in hand or a J31/J32, without taking the watch apart.
Use a caliper and messuare carefully the distance between the top of the top plate and the top of the bottom plate. If more than 4 mm it is a J26.

Another feature which distinguishes the J26 from a J31 and a J31 from a J32 are the amount of screws on the balance wheel.
J26 14 screws, J31 8 screws and the J32 has 16 screws.
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