Atmos Question

Discussion in '400-Day & Atmos' started by GjP, Feb 25, 2016.

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  1. GjP

    GjP Registered User

    Jan 9, 2011
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    Hello. I recently purchased an Atmos clock, the baby Atmos. It will run for 3 or 4 days then stop. Sometimes when it stops the minute hand will spin freely. If I reach in and manually wind the mainspring with my finger the clock will run again. It runs and keeps accurate time. But in a couple of days will stop again. I manually wound it a couple of times then decided to check the bellows. I pulled the bellows off it was dated 1956 and checked it's movement. Set it in the frig for a couple of minutes and measured then let it sit at room temp approx. 70F and measured. Got the numbers listed in one of the Atmos books. While off and the mainspring was unwound I pushed the back of the plate on the end of the large coiled spring. It only wound the mainspring a couple of times then seemed I had to pull a little on the coiled spring to wind. The mainspring seems kind of stiff or hard to wind?? It seems that the coil spring doesn't have enough strength to wind the mainspring? Or could it be the mainspring needs cleaned and oiled?? If the mainspring is wound the clock seems to run fine. The clock is in very nice condition for the age and I would really like to get it working. Any suggestions as to what to try? thanks Oh I also measured the distance of the coil spring it was approx. 48mm.
     
  2. etmb61

    etmb61 Registered User
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    Oct 25, 2010
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    Retired Avionics Technician
    Mascoutah, IL
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    If you wind the Atmos "by hand" by compressing and releasing the spring in the center of the bellows it will reach an equilibrium with the mainspring. That's normal operation. If you then pull on it you can damage the winding mechanism.

    Eric
     

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  3. GjP

    GjP Registered User

    Jan 9, 2011
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    How many times should you be able to compress the spring before you reach the equilibrium?
     
  4. etmb61

    etmb61 Registered User
    NAWCC Member

    Oct 25, 2010
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    If the mainspring were completely let down, the winding arbor should turn 5 to 7 times to reach the equilibrium. For the clock pictured, that was the condition after 7 compressions of the spring, but as I recall it did not completely extend after the 4th or 5th.

    You should note that in normal operation the coil spring only winds the mainspring as the temperature drops and the bellows only compresses the coil spring as the temperature rises.

    Can you post pictures of your clock?

    Eric
     
  5. Ed O'Brien

    Ed O'Brien Registered User
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    Nov 30, 2009
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    Retired, and now full-time clock repairs.
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    Problem may not be with the bellows, but a dry or dirty mainspring. Clock is very sensitive and needs full performance from the mainspring. After disassembling an Atmos I first measure the depth of the bellows, then disassemble, clean and libricate the mainspring.
     
  6. GjP

    GjP Registered User

    Jan 9, 2011
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    I also thought I may be a dirty mainspring. But before taking things apart I thought I would check everything one more time. Last night I brought the clock back down to my bench and removed the case and bellows again. I check the bellows movement from chilled to room temp, it moves 10 to 12 mm. I also wound the mainspring to equilibrium approx. 5 compressions the last time the coil stayed compressed at 26mm when expanded it was 46 to 48mm. I released the pendulum and started watching the movement. I noticed that every so often the bottom tip of the pend would touch the secondary bottom lock. I opened the screw as much as I could, doesn't touch now. I also noticed that the fork touched the fork stop on the left side and there was clearance on the right. I touched the stop just enough to give it a slight clearance. I check the bushing between the fork I rotates freely. I set the time and started the pend again. I checked the pend rotation one side was slightly less than the other. I let the clock run overnight and checked this morning before leaving for work. Pend rotation seems to be equal on both sides 360 to 380 degrees (approx.) Time was also correct. The clock hasn't run for more than 4 days, I think i'll let it run like this and see what happens. I'm at work now will post pictures of the clock when I get home.... thanks again for all the help.
     
  7. GjP

    GjP Registered User

    Jan 9, 2011
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    Here's the picture SAM_0119.JPG the one on the right..
     
  8. GjP

    GjP Registered User

    Jan 9, 2011
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    Still running strong and keeping time.. just an update
     

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