J29 1924 - 1929
J29a 1930 - 1953
J29 1st. and 2nd version
J29a, J29/1, J29/II, J29a/II
1/5 sec. = 18000 A/h
1/10 sec. = 36000 A/h
U425, 428, 1742st
Zf 2,1 mm x 13,5 mm x 0,13 mm
Junghans mentions spring # 1005
515 x 2,15 x 0,13 mm
F.W.S 1952 page 46
Junghans catalog 1927 text:J29, Timing watch movement, 4 jewels, compensating hair spring, club teeth escapement, double safety rollerJunghans catalog 1934 text:
J29a, Timing watch, bridge movement, 4 jewels, compensating hair spring, club teeth escapement, double safety roller, gilt platesRegistering 1/5th seconds or 1/10th seconds.Junghans catalog 1950 text:Timing watch, bridge movement J29a, 4 jewels, Nivarox hair spring, pin pallet escapement, double safety roller, gilt plates1/5th seconds division, 1/10th seconds division, 1/100 minutes division
J29 first edition
The operating lever spring is from an J29A, probably as a repair.
J29 second edition
The change is a new simpler operating lever spring and hammer spring.
Multiple parts have been simplified.
Here is a J29 timing watch with a tachymeter scale for 200 meters. If you follow a runners 200 m race and the runner finishes after 20 seconds you can read the average speed for the race was 36 km/h.
The J29c is a J29a which was built from February 1944 for the German Navy as a special submarine hunting timing watch in an 71 mm case and with special dial illuminating as seen in the pictures.