Clock only strikes one

Question

QUESTION: Hi - I recently purchased a grandfather clock that has a Urgos movement. It chimes Westminster perfectly on each 1/4 hour, but at the top of the hour, it only strikes one time, regardless of the hour.

After chiming, it only rings a single strike and i'm not sure how to get it to strike 2-12. Otherwise the clock runs great. Any advice? Does it require that I purchase an entirely new movement or is there something i might be missing? Any advise is greatly appreciated.

Thanks - Jason

ANSWER: Jason, you have a clock movement with a "rack and snail" strike mechanism. When the clock prepares to strike, the rack, which has teeth on it, falls down on a cam that looks like a snail. The snail has 12 different levels and each one is associated with the hour hand. When the clock strikes, it lifts one tooth for each hour struck, i.e., one tooth, one strike, two teeth two strikes, etc. There can be one of two causes for it to only strike once. One is that the lubricant in the rack pivot is gummy and not allowing it to fall past one tooth. The second one is that lift mechanism linkages between the cam on the minute hand shaft and the rack release lever have worn or been bent so the rack is not allowed to drop past the first tooth. Both of these causes are rather common on clocks that have not been serviced on a regular basis. To observe what is happening, the dial must be removed from the movement. This usually requires the services of and experienced clockmaker. This particular problem should not warrant purchasing a new movement, but the condition of other parts could help make that decision.

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---------- FOLLOW-UP ----------

QUESTION: I appreciate your response. I have some additional information which my help to pinpoint the issue. I'm certainly not afraid to give this fix a go...

There's a lever on the top left of the movement (if I'm looking into the back of the clock). I've found that when i press that lever, the clock will chime and/or strike multiple times. Does that help to narrow things down at all in favor of worn or bent lift links vs a gummy rack pivot? Again, I really appreciate your help.

ANSWER: I'm not sure what that lever is. Can you send a clear photo to my shop email address below?

---------- FOLLOW-UP ----------

QUESTION: OK - this is my last question, I promise... I opened the face of the clock so I could get a better look a the rack and snail mechanism. It appears as though my problem is related to the cam which lifts the rack release rod. The cam has 4 notches which correspond to each of the quarterly chimes, and a "nub" or "bump" which lifts a bar that allows the rack to fall into position (against the snail)at the top of the hour. I noticed that the "bump" on this cam doesn't lift the release bar quite far enough to clear the end of the rack, ie, not allowing it to fall into the engaged position. I tied a little string around the cam, creating a slightly higher "bump", and with it, the mechanism works perfectly - the release clears the rack and it strikes as expected. My question is...what's the proper name of that cam that I tied the string around, and is it a part I can buy? It looks like the cam is attached to its seating pin with a small tension screw... I envision that if I loosten that screw, it should pull straight off. I'm thinking the bump on that cam may have just gotten worn down over 40+ years of striking... It's been striking perfectly since i tied that string around the cam, making that bump just a titch higher.

Answer

Jason, you have done an excellent job in diagnosing the problem! First on nomenclature, the cam to which you are referring is the chime locking plate. The high point on it is called a lobe. The lever it lifts is called the chime/strike lifting lever. This lever lifts a rack hook that allows the rack to drop. A worn high spot on the chime locking plate is one cause of reduced lift. A defective (worn or bent) chime/strike lifting lever is another cause. Sometimes I can form this lever to compensate for a little wear in the complete mechanism. But too much adjustment can cause another problem in other parts of the operation or can mask another area of increasing wear that will cause failure again. When we work on these mechanisms we have to consider all of the possibilities. At this point it could be a worn lobe on the cam. I can probably locate that part for you. It might have to be a good used part, as Urgos is out of business. Hermle did buy out the tooling and parts, and they do now make some of the movements. I don't mind follow up questions, but would you direct them to my shop email address in the previous answer, as I have a limited number of Allexperts questions per day and it helps free up the queue. Also, now that you have the dial off the movement, is it possible for you to send me a clear photo of the front of the clock so I can better identify the parts, along with the information found on the back plate of the clock movement?