Atmos impulse roller action explained

Discussion in '400-Day & Atmos' started by zygo, Oct 11, 2017.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. zygo

    zygo Registered User

    May 29, 2008
    28
    1
    3
    Essex UK
    Country Flag:
    Can an Atmos Expert please explain definitively the purpose and action of the impulse roller spring (#5304) and roller mounting collar (#3507) on the Atmos?

    Obviously the fork is pushed to one side (providing the impulse to the roller) as the teeth of the escape wheel pass across the faces of the pallets - this is the same in any clock. But most don't have a coil spring. Would it be right to assume that the spring is added to enable the escape wheel tooth to pass more quickly across the pallet face (rather than a less efficient slow drag) and in so doing apply a little tension to the coil spring, which then releases more slowly to propel the roller, taking the balance with it?

    If so, is the purpose of the collar simply to restrain the coil spring on the balance stem? For that to work, the lower pipe of the roller mount would need to be an easy fit in the main balance stem, with no sense of tightness or friction. I have a 519 where the collar was fitted too high, and seems to have distorting the very top of the balance stem, causing some drag between it and the roller mount just inside it. The amplitude is low and I think what's happening is that the balance is being turned directly by the action of the escape wheel teeth directly on the pallet faces; the coil spring is in effect doing nothing.

    Thanks in advance.
     
  2. etmb61

    etmb61 Registered User
    NAWCC Member

    Oct 25, 2010
    1,526
    6
    38
    Retired
    Mascoutah, IL
    Country Flag:
    Region Flag:
    According to Living on Air, the spring prevents damage to the roller pivot caused by mishandling. It also says the spring is strong enough to maintain the angular position of the roller during normal operation, but not so strong as to distort the fork from mishandling.

    It's a safety feature.

    The collar is where you set the pendulum in beat.

    Eric
     
    zygo likes this.
  3. zygo

    zygo Registered User

    May 29, 2008
    28
    1
    3
    Essex UK
    Country Flag:
    Thanks for this, Eric. I had not noticed that paragraph before; it's not very prominent, nor indeed very easy to understand. For other readers it's at the bottom of p47 of LOA, (diagram 29, p48) and says that the roller's "angular position is determined by the cylinder spring" - I'm not altogether sure why the angle of the roller should change, or why it's not just set upright, nor even how the spring can possibly control its angle. Very mysterious. I'm wondering if the author meant the "rotational" position of the complete roller assembly in the top of the balance tube because that would be closer to my own summation.
    This also matches the procedure of repositioning the collar (and thus the spring and roller) to set and fix the roller at the front when stationary (so that the clock is in beat). And if it has no other purpose, it reinforces my view that the roller assembly should sit freely inside the top of the balance tube, not clamped by the collar, to allow the roller assembly to rotate when driven by the impulse of the fork, albeit under the restraint of the spring.
     
  4. etmb61

    etmb61 Registered User
    NAWCC Member

    Oct 25, 2010
    1,526
    6
    38
    Retired
    Mascoutah, IL
    Country Flag:
    Region Flag:
    The coil spring should not deflect under the impulse from the fork on the roller. If the roller were in a fixed position on the balance staff, with no coil spring, the clock would run the same.
     
    zygo likes this.
  5. zygo

    zygo Registered User

    May 29, 2008
    28
    1
    3
    Essex UK
    Country Flag:
    Well, that sounds like a definitive answer - thanks Eric.
    I guess that all the spring really does is protect the fork if the hands are moved while the fork is engaging the roller. Thanks for clearing that up. I now need to find another explanation for a meagre 360 degree amplitude after servicing. Back to the drawing board .....
    It's funny how some Atmos clocks don't perform as well as others after servicing.
     
Loading...
Similar Threads - Atmos impulse roller Forum Date
What devices have you built to poise the balance and the fork on a Atmos Clock. 400-Day & Atmos Today at 10:13 AM
Atmos. Are there any plans in the works for a new tutorial DVD? 400-Day & Atmos Monday at 3:25 AM
ATMOS 560 Calendar setting 400-Day & Atmos Sunday at 12:05 PM
ATMOS 560 CLASSIQUE Phases de lune 400-Day & Atmos Oct 3, 2017
Atmos clock question: impulse roller mounting, why it is “floating”? 400-Day & Atmos Nov 26, 2015

Share This Page