Strike Count not synced on ST 120L Movement

Discussion in 'Clock Repair' started by Jeffrey Smith, Oct 20, 2018.

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  1. Jeffrey Smith

    Jeffrey Smith Registered User
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    Sep 7, 2018
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    I'm counting on your help again for this movement. I cleaned and oiled the movement, and during that process disassembled the entire thing. After putting it back together, and running tests, I could not get the number of strikes on the hour to agree with the position of the hands. For example if the hands read 7 it would strike 6 times, and so on.
    After reading several postings here, I thought perhaps the gathering pallet was loose or not positioned correctly, so I lifted it off its shaft, and started by trial and error to find the proper position. About six hours later I got it to the point where the clock will strike the hours properly any time from 2:30 through 12:30. GP Normal Position.JPG 100 GP Position.JPG 130 GP Position.JPG
    The picture on the left shows the position of the GP at its "normal" position after the strike is complete where the pin is oriented so it lies just above the rack teeth (at about 230 position for the pin on the GP) . When the movement runs from 2:30 through 12:30 the number of strikes is correct both on the half hour and hour. After the clock strikes once at 12:30, and the clock approaches 1:00, the warning starts and the rack drops with the tail hitting the snail in the highest position. The clock strikes once, and the timing train stops, but the GP is still engaged with the rack (see center photo). As the hands advance to 125 the warning sequence starts, and the GP rotates slightly but not enough to disengage the rack. At 1:30 there is partial movement of the timing train, but not enough to move the hammer. As time approaches 1:50 the first warning is heard, but again no rack movement because of the pin engagement. At 2:00 the timing train starts but only partially, and the rack is released because the GP has rotated enough to disengage it. At that point the rack and GP are back in the "normal" position.
    My suspicion is I still do not have the GP oriented properly, but after spending six hours trying to find the right position, I really don't want to start over again. Can anyone tell me the proper way to locate it, or offer any other ideas?
    Thanks
     
  2. shutterbug

    shutterbug Moderator
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    Oct 19, 2005
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    You might have to take the GP off again, and reposition it a bit so it clears the rack.
     
  3. R. Croswell

    R. Croswell Registered User

    Apr 4, 2006
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    I believe you have two and possibly three problems here. First you will need to remove the clip and retaining washer then lift the snail and back it up one tooth and put it back. Make sure that when it is released at 12:00 that it does not contact the 12-1 wall on the snail. Nothing else will work right until you fix this.

    When the strike finishes and the train locks there are two conditions that must be achieved -
    1) the gathering pallet must be positioned clear of the rack teeth so when the rack is released again the teeth will not catch on the gathering pin.
    2) the strike hammer must not be left partly raised. and must not start to raise when the clock goes into the warning run just before striking. This can usually be achieved by carefully adjusting the gathering pallet, but you may need to re-time the strike star wheel with the stop wheel.

    RC
     
  4. Jeffrey Smith

    Jeffrey Smith Registered User
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    Sep 7, 2018
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    RC,
    Your suggestions were spot-on! I spent some time through trial and error repositioning the gathering pallet. I also noticed the pallet was slightly loose on the shaft, so my previous attempts to synchronize were all in vain, akin to a dog chasing its tail. After making sure there was clearance off the rack at all times, and that the strike count was correct throughout several complete cycles, I used a hollow tube and tapped the pallet for a good press fit. The striking hammer of course was now lifted in the air, so I spread the plates and repositioned the star wheel so the hammer is fully down even after the warning run starts.
    I did not reposition the snail and there is just enough clearance between the rack tail and 12-1 wall on the snail. I now have the movement back on my test stand and will run it for a week before re-installing it in its case.
    Thank you again for everyones input!
     

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