Spring run away

[chuckc]

Having a persistent problem in an 1870’s French Pillar clock. To give you some insight into the problem, the lift lever unlocks the train into warn. The train rotates to the warn tab without any issue. The lift lever continues to rise releasing the warn pin and the train starts the strike. All sounds pretty clear except, intermittently, the spring unwinds, but it is not like when it just drives the strike normally. It is more like the spring getting away from you during let down or outside the barrel. It is really a violent release of energy. It will unwind almost completely and it happens so quickly you cannot tell or see what actually occurred. The count wheel contains ridges and flats so once it goes into this condition, the count wheel cannot stop the forward motion and even though the lock tab is falling when it drops to a flat, the sequence is so far out of time that when the lock pin arrives, the locking tab has been lifted by another ridge. The spring releasing all energy stops the motion. What is so frustrating is, I know what is happening but I cannot see the why.
I have tried to recreate the problem outside the frame without success by simply holding in my hand. When it is installed into the frame, it is very difficult to see what is happening. Because this movement is round, I am trying to find a movement holder that can hold the movement without it trying to jump out during the intensity of the spring releasing. I would like to do a slow motion video to evaluate but because it is intermittent, I need to be able to setup the camera and wait. Any suggestions will be appreciated or if you have seen something similar in your careers, I am all ears. Even if you are new to the hobby/business, please don’t hold back.

 

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