The Junghans 687.00 shown here is from 1963 (production code F3). It’s one of the latest versions with fixed hairspring stud, originally an 87/10.
Unlike most of the common Junghans movement, it has got the “full” mens' watch movement size of 11 1/2 lignes. Due to that, the balance wheel has got a large diameter and beats slowly with 18000 A/h.Video on YouTube
The screwless two leg ring balance (with slightly tailored-out legs, which is an indicator for a Glucydur balance) is beared in two Junghans-inhouse shock protection bearings which look very unique due to their large deck jewels.
The gear train construction is contemporary with the pallet lever regulating the balance wheel, which is on the upper side beared under a cap jewel. Following are the directly driven center second wheel, the third wheel, the center located minute wheel and the mainspring barrel.
On the dial side, you see the yoke winding system. Many other Junghans movement of that era only used a rocking bar winding system.
You also spot the Junghans shock protection with its large cap jewel.
In the lab
|dial up||+10 s/d|
|dial down||-8 s/d|
|crown right (12 up)||+20 s/d|
|crown up (3 up)||+-0 s/d|
|crown left (6 up)||-30 s/d|
|crown down (9 up)||-10 s/d|
|Size:||11 1/2''' (measured: 25,6mmmm)|
|Number of jewels:||17|
Glucydur anular balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||2 hole(s)|
|Production period:||1962 - ~1963|
Flume: K3 15|