Expert: Martin Meyer - 9/18/2008

Question
I have clock with a Hermle 340-020 movement, it has the FSS balance unit. I have cleaned and oiled the unit, but the clock will only run for a few seconds. Do you have any ideas what might be wrong? Does any thing else power the clock besides the main spring. After I wound the main spring I didn't see it turn.
Thanks for your help
Ken

Answer
Hi Ken,

There are many possible causes for a clock's not running, and I'm not able to narrow them down without inspecting the movement, but I can suggest some possibilities. If the clock is older (12-20 years) there may be wear in the movement's bearings. It is also possible that, in an older clock, the mainsprings have lost their tension, and need to be replaced. If the movement was not fully disassembled before cleaning, there may still be dirt and dried oil in the bearings. Lubrication must be done with clock oil only, preferably a good quality synthetic. If not synthetic, the oil must be fresh. Use of penetrating oils such as WD-40 can stop a movement. It is possible, although less common, that there is a damaged gear tooth or a bent pivot (tip of the gear shaft that turns in the bearing hole).

The escapement itself is very delicate in this movement. The hairspring could be bent, the balance staff (shaft) tips could be dirty, rusted or broken, the verge fork could be out of adjustment or the pin pallets could be bent or out of adjustment. It is possible, but unlikely, that the escapement is out of beat.

The center mainspring is the only source of power for the time train. The mainspring barrel turns too slowly to be visible.  http://www.clockmasteronline.com