main spring break

[lad111]

I had just finished cleaning and reassembling this Junghans A12 movement, setting the beat when it stopped running after 2 hours.
When trying to readjust the beat the main spring (strike) snapped in two the clock started running again. Not sure what caused this…..besides taking about a year off my life I was wondering if the timing sequence had something to do with this break.

[willofiam]

OUCH 😯 not fun when that happens, hopefully your o.k. and most important, is the clock o.k. 😆 I would think that it stopping may be because of this spring getting ready to break but not sure though. I cant imagine adjusting the beat would cause the strike mainspring to break. Did it hurt anything in the movement? Is it still running? William

[lad111]

Yes the clock is still running and there appears to be no other damage.

[willofiam]

Good news, do you think that the strike train was binding (with the bad mainspring) and causing the time train to stop?

[lad111]

Do not know nor do I know how to find that information out. Suggestions, I will be putting a new spring in, once I take this one out and measure it.

[arutha]

That mainspring would have been on its way out, just adjusting the beat wont do that to a mainspring even if the strike side had locked up and in turn locked up the time side, if you were forcing the hands in this situation then the hands should have broken before the mainspring. As William suggested, check for damage, bent trundles in the lantern pinions and bent teeth will be the most common faults found after a broken spring.
Glad you still have all of your fingers and eyes, not a nice experience
Paul.

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