Franz-Hermle 340-020 runs slow

Posted: Sun Mar 16, 2008 3:35 pm     Post subject: Franz-Hermle 340-020 runs slow

I was given this clock by a friend and find that it is running about 15 mins/day slow. I can not find anywhere on the clock a way to adjust the speed. Can you advise?



Also, I was wondering the age and value of the clock -- it is in perfect condition. Additional markings on movement are W[(2) JEWELS Unadjusted Made in West Germany (stamped with "81") on back plate. Can you advise on this too?

Posted: Sun Mar 16, 2008 11:10 pm     Post subject: Hermle 340 020 movement

The '81' stamped on the back plate is the year of manufacture (1981).

Do you know if the clock has been serviced at all? It may very well be in need of cleaning and lubrication rather than any speed adjustment. Certainly a clock movement that is 27 years old is long overdue for maintenance if it has not been done recently.

Speed adjustment is done on the movement itself inside the back of the case. There is a small pointer on the top of the oscillating escape wheel. There are also a series of dimples on the wheel. There may also be a + and a - stamped on the back plate. The pointer on the escape wheel should be moved in the + direction to speed up the movement. This is a delicate operation. The escape wheel should be held firmly but carefully while the speed is being adjusted. Move the pointer only in small increments (one or two dimples at a time) allowing 24 hours in between adjustments and observing how much time is gained. Additional adjustments can be made each 24 hours until the correct time keeping is finally attained. If the pointer is already at the end of travel on the wheel do not force it. The clock is then definitely in need of proper service.