Clocks, Watches/Hermle Mantle Clock
I've just been given a Hermle model 340-020 mantle clock. It chimes on time, but is loosing time. Looking at the back of the clock mechanism, I can see a '+' and '-' marks, but no Platform Escapement seems to be fitted. I was wondering if this is an early model,built before Platform Escapements were fitted, and how do I adjust the timing.
Thank you in advance.
Your clock movement has what is called a "floating balance". Yours is the early design. The newer one has a coil hairspring instead of the "worm" spring on yours. This movement model never had a platform escapement. Yours is more difficult to adjust the timing on.
First of all; the movement must be running well or it will not keep time. The disc on the balance should make close to one complete revolution when the clock is running. If you get 75% or less that a full turn your problem may be that the clock is not running well.
Having said that I'll tell you how the adjustment is made. On top of the disc there are some prongs pressing down onto it. Hold the disc and push one of the prongs in the direction of the + to speed it up or to the - to slow it down.
I hope this solves your problem.
clock parts and repair