Unusual (?) Chelsea Movement

Discussion in 'General Clock Discussions' started by Uhralt, Oct 11, 2019.

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  1. Uhralt

    Uhralt Registered User
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    Here I have a Chelsea clock movement. The serial number puts it in the early 1940s timeframe. On first sight it looks like a regular ships clock movement (time only). Looking closer, it appears that it is wound from the back, so more likely it belonged to a mantel clock or similar. There is also a mechanism to set the hands from the back, so maybe the front of the clock was sealed so that the time couldn't be set by pushing the minute hand. What strikes me most is that little fancy knob on the back. When you turn that knob, a small, soft spring comes out and pushes against the rim of the balance wheel, thus stopping the clock. I wonder what the purpose of this was. Was it to allow to set the clock "to the second"? Or, was this a clock to be used as a stop clock, like maybe in a lab?

    I wonder if anybody has seen a complete clock with this mechanism that shows what its purpose was. I have the movement only.

    Thanks for any information.

    Uhralt
    chelsea18.JPG chelsea19.JPG chelsea20.JPG
     
  2. shutterbug

    shutterbug Moderator
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    Harold used to repair fish feeder clocks - released feed at specific times. Yours could have some odd purpose like that.
     
  3. Uhralt

    Uhralt Registered User
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    It must be something very odd. I searched the web for information and found that there were Chelsea clocks with a similar on/off mechanism (by stopping the balance wheel with a piece of spring attached to a lever) that were used during WWII on Navy vessels. These are the so-called zig zag clocks. They helped ships travel as a convoy in a coordinated zig zag course to avoid torpedo attacks. These clocks had levers either at the side of the case or on the dial to start and stop the clock, compatible with the classic ships clock cases. However, this movement is wound, set and stopped from the back, which wouldn't be feasible when mounted to a wall.

    Uhralt
     
  4. Uhralt

    Uhralt Registered User
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    Shutterbug,
    Can you move this thread to the General Clock Discussions for more exposure? It is not really related to repairs.
    Thanks,\
    Uhralt
     
  5. shutterbug

    shutterbug Moderator
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  6. Uhralt

    Uhralt Registered User
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  7. Uhralt

    Uhralt Registered User
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    Another weird thing I just noticed is that both the stop wheel and the slow/fast regulator wheel are lower than the mounting posts for the back plate (see first picture). So, with a back plate mounted, both wheels could not be manipulated. Does that make sense at all?

    Uhralt
     
  8. kinsler33

    kinsler33 Registered User

    Aug 17, 2014
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    The term is 'hack watch.' My father's WWII Hamilton military pocket watch would stop when you pulled out the stem to set it. The idea was to tune the time signals on the radio, set the watch to exactly the next minute (with the second hand on 60) and wait for the beep from the time signal. When you pressed the stem back to the 'wind' position, your watch is set perfectly.

    My old man used to do this every evening, tuning in WWV on his Hallicrafters short wave radio. I've noticed, however, that my spouse Natalie's little quartz Seiko watch has exactly the same feature.

    I wonder if Uhralt's clock was meant for some special cabinet in the captain's cabin.

    The information about the zig-zag clock, however, is fascinating, and thank you. You would _not_ have wanted to send a radio signal to other ships in the convoy to tell them when to zig or zag.

    M Kinsler

    We are the cleverest creatures imaginable whenever we're trying to kill each other.
     
  9. Bill Cann

    Bill Cann Registered User
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    I serviced a Chelsea like this for my brother, Navy documents show my brothers to be a Model 17E. He inherited it from our grandfather who served as Medical Officer aboard the USS Shasta in WW2. My grandfather said he acquired it when the Shasta went to the salvage after the war. The Model 17E has a rotating back cover plate that covers all the openings (stop/start wheel, winding, regulator, etc) presumably to help keep salt air out of the movement.

    There is a good repair/parts manual for the Model 12E and 17E ships clock- NAVSHIPS 250-624-8. Was interesting reading.

    Bill

    IMG_1332.JPG
     
  10. Uhralt

    Uhralt Registered User
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    Thanks Mark and Bill!
    Now it all makes sense. Especially the rotating back plate explains why all the setting are underneath the backplate but can still be used! Is this service manual available anywhere?

    Uhralt
     
  11. JTD

    JTD Registered User

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    Yes, it is. It is available free as an e-book on the internet, or you can just read it (or print it). the only problem is, I don't know how to send you the extremely long internet reference.

    All I can do is say that if you put NAVSHIPS 250-624-8 into google, then on the first page of what comes up you can scroll down to 'Manual for Repair, Overhaul and Handling of US Navy...' and click on that. The whole manual is there for you to read, or you can download it as an e-book (free) by clicking the red tab on the left hand side.

    Hope this helps.

    JTD
     
  12. Uhralt

    Uhralt Registered User
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    Thank you! I found it:

    Manual for overhaul, repair and handling of U.S. Navy mechanical, boat and deck clocks, Chelsea type, with parts catalog.

    Uhralt
     
  13. JTD

    JTD Registered User

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    That's it! Glad you found it.

    JTD
     
  14. Bill Cann

    Bill Cann Registered User
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    I just have a hardcopy, so glad you found it on the net.

    Pay close attention to the authorization table of who can do what. IIRC, only a Navy Certified Senior Clock Technician is authorized to disassemble the movement. :)

    Bill
     
  15. Uhralt

    Uhralt Registered User
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    Hopefully I didn't already commit a crime. Getting nervous now..:eek:

    Uhralt
     
  16. Uhralt

    Uhralt Registered User
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    The manual is very interesting reading. It is extremely detailed (maybe something typical for military applications) and has some remarkable statements. One is that a clock should get a full service every year or every other year. Another one is that at the full service the mainspring should routinely be replaced with a new one. Wow! Imagine buying a new mechanical clock with the prospect to investing $ 200 to 300 every year for service......

    Uhralt
     
  17. kinsler33

    kinsler33 Registered User

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    But this particular clock was a weapon of war, and thus no expense was spared. One need only look at the precision time fuzes (that's the right spelling, I think) that went into precision-made shells to be used by the hundreds in rapid-fire anti-aircraft cannon.

    That's war, mankind's most highly-developed and lavishly-financed pursuit.
     
  18. Uhralt

    Uhralt Registered User
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    You are probably right!

    Uhralt
     

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