Complete service to a Hermle but it is losing power and running too fast

[stephan135]

Hello. I am working on a Hermle 340-020 movement.

I disassembled the whole movement, did some bushing work, cleaned and oiled it, but it's running too fast. Like 10 minutes every 4 hours.

The floating balance wheel is barely turning so I believe it is losing power, since it is only turning between 100 and 120 degrees.

I already tried to change and split the mainsprings and it still works bad. I also tried to test the floating balance wheel in another hermle movement and now it turns more than 360 degrees, so I don't think there is a problem in the mainsprings and the floating balance wheel.

It is hermle movement from 1978. I am not sure what else can be done since I already tried to service the whole movement.

I am attaching two pictures of how the movement looks like and a video where it can be seen that the floating balance wheel barely turns.

Video:

 

[Willie X]

Looks like that one has seen a lot of action ...

You could try this: let the main springs down, removing the balance assembly and pallet arbor, then add power one click at a time to the going train. At about the 3rd click the escape wheel should turn slow and steady for several minutes. If this doesn't happen, you will have to find the problem/s in the gear train. Willie X

 

[wow]

The floating balance should be cleaned well and not oiled at all. I clean them with naptha followed by denatured alcohol. Once clean, the balance should rotate about two minutes on its own if mounted in a vice. The barrels and caps often need bushing. If they are sloppy and the barrel slants, power is lost. You may also have a too tight bushing causing loss of power. These movements are unforgiving and must have full power in each train to operate well.

 

[dickstorer]

Why don't you have the caps over the Pallet Fork pivots? The depthing of the PF into the floating bal. is critical.

 

[MARK A. BUTTERWORTH]

Quite often the time 2nd wheel is bushed too close to the 3rd wheel as well. It was already punched marked