Clocks, Watches/Hermle Movement Doesn't Stop Quarter Chiming
I've had the movement in a grandmother clock for over 30 years and other than routine cleaning / oiling have never had a problem. Lately however the quarter hour chimes do not go off @ 15, 30 or 45 minutes but @ the hour, they go off for the hour, then continue to go off while the hour chimes also go off. I also note that the quarter hour chime gears do not seem to set at the 'warning' point as they should. I've looked carefully at the movement during this and it appears that the lever that engages the quarter hour cam wheel on the front face of the movement doesn't drop far enough to allow the 'dog's (there are 2 of them) inside the movement to engage the pin on the quarter hour butterfly gear. Sorry if I'm not using the right terminology. While both 'dogs' I described are driven by the lever raising and lowering, one appears to be fixed to the shaft, while the other has an adjustment screw. Wondering if this is what is need of adjustment? I can provide pictures of the movement and some of the relevant parts if helpful.
Thanks in advance, this one has me baffled.
Dave, even with proper maintenance, mechanical devices do eventually fail and repair or replacement is necessary. Don't worry about the technology. You did a very good job in describing the problem and area in which it was happening. You did not give me the manufacturer and model number of the movement, so I'll just have to give you some general information. Emperor used two models in their grandmother clocks, first the Jauch, which usually has a "77" on the back plate. They to Hermle somewhere in the 1980's, an the movements were the 451-050 94cm models. The Jauch movement had the two levers between the plates. The Hermle has the two levers outside the front plate. I will describe the Hermle setup. The two levers with the "dogs" are the chime locking lever and the chime correction lever. The small round cam with the "V" shaped indents in it is called the "chime locking plate", and as you can see, it has spaces between the indents that vary increasingly as the cam turns CW. This is to allow 4, 8, 12 and 16 notes to play to the quarters. On the back of the locking plate is a cam with an indent that drops the correction lever when the movement (not necessarily the hands)reaches the 3/4 hour. No matter where the hands are, it will stay locked until the minute hand reaches the hour. The star cam on the minute shaft has 4 points on it to trip the quarter chime motion. One of the points on the cam is higher than the 3 others. It is on the hour position. If the chimes get out of sequence, like when the time is reset or it stalls because it is wound down, the correction lever will remain there until the hour when the high point on the star cam lifts it enough to unlock the chime. Then the chimes are back in sync.
You say that:
1. The warning does not occur at the quarters, and in your case it would be logical to occur at the hour since it does chime and strike (The warning can be compared to cocking a gun after each firing).
2. The chimes do not trip except at the hour.
3. The chime continues after the strike starts.
It would take a few hours of instruction to diagnose and determine what the actual problem is. It probably has to do with the sync of all the components, worn parts reducing their motion, or maybe even gummy lubricant. If the warning is happening on the hour, then this would probably not be the problem. On the worn parts one has to consider the wear of the star cam, the chime warning lever, and points on the chime locking lever or the chime correction lever. Or as you had suggested, the lever with the adjustment screw could be adjusted to compensate for some wear or slippage. To correct all of this, it has to be done in sequence, as one adustment can put another out. If you will send a couple of photos to my shop email address below, I will take a look and see if I can give you any help.
Vintage Emperor Clock Consultant
THE VILLAGE CLOCKSMITH
Note concerning questions not related to Allexperts: Because of my commitment to answering Allexperts questions within a prescribed time limit and the large backlog of clock work at my shop, I regret that I cannot answer personal email questions on a timely basis, other than Allexperts follow up questions. I will try to answer these emails as soon as I can. Thank you for your patience.