Bizarre Hermle Situation

[bchaps]

Hi...I came across a chime failure on a client's clock that I find bizarre. The Client indicated her Westminster chime clock has not run for some time. Since the clock was purchased in the 1980's and also due to the dried condition of lubricants, I don't believe anyone has ever serviced the clock. After removing the Hermle 341-020 from the case, I did my normal check-over before beginning disassembly. I discovered the star cam on the center arbor did not provide enough lift to release either the chime locking lever or the chime correction lever...these are the two front-mounted levers that control the chime run. By adding a bushing to each of the lifting pins (see photo), adequate clearance was provided to correctly release and capture the chime function.

My dilemma is that there is no obvious indication the chime warning lever which rides on the star cam has been bent or compressed in some way to reduce the amount of lift. In addition, the tapered stud which rides on the star cam is tight and shows no significant wear, However, the star cam is scored which indicates the hands have been turned backwards. Is it possible that while turning the hands backward, the chime warning lever could have been bent slightly , reducing the amount of lift??? This appears to be the only possible explanation. If you have encountered a similar situation, I would appreciate your comments. Thanks, Bill

[bchaps]

Hi...I came across a chime failure on a client's clock that I find bizarre. The Client indicated her Westminster chime clock has not run for some time. Since the clock was purchased in the 1980's and also due to the dried condition of lubricants, I don't believe anyone has ever serviced the clock. After removing the Hermle 341-020 from the case, I did my normal check-over before beginning disassembly. I discovered the star cam on the center arbor did not provide enough lift to release either the chime locking lever or the chime correction lever...these are the two front-mounted levers that control the chime run. By adding a bushing to each of the lifting pins (see photo), adequate clearance was provided to correctly release and capture the chime function.

My dilemma is that there is no obvious indication the chime warning lever which rides on the star cam has been bent or compressed in some way to reduce the amount of lift. In addition, the tapered stud which rides on the star cam is tight and shows no significant wear, However, the star cam is scored which indicates the hands have been turned backwards. Is it possible that while turning the hands backward, the chime warning lever could have been bent slightly , reducing the amount of lift??? This appears to be the only possible explanation. If you have encountered a similar situation, I would appreciate your comments. Thanks, Bill

[Mark A. Butterworth]

The Hermle unit has very tight tolerances. When the 4th chime pivot hole wears (the one containing the locking cam), the direction of wear is vertically upward. As a result, over time the unlocking lever has to lift higher than it did when new. As a result it is very possible it does not lift high enough to unlock the train even though the unit has not been work on or altered. The solution is to relocate a bushing in the proper place.

[bchaps]

Thank You Mark. Great suggestion! I can see how bushing hole wear on C4 could cause the problem. I rechecked C4 and found minimal bushing hole wear...about .2mm on a 1.8mm arbor, just enough to be visible, but not enough play to normally cause concern. But, as you mentioned, the tolerances are tight and minimal wear may just be sufficient to cause this failure. So, after cleaning the movement, I'll rebush C4,relocating the hole downward very slightly. Thanks again for your help.

Bill