Swing in torsion pendulums

Discussion in '400-Day & Atmos' started by cucoclock, Aug 15, 2011.

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  1. cucoclock

    cucoclock Registered User

    Jul 17, 2005
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    Hello all,

    I would like to know your opinions about the way torsion pendulums moves when they are regulating a 400 day clock.

    The only movement I would like to see in this kind of pendulum is a rotative movement.

    But, if you look at carefully sometimes the are two movements:
    1) Rotation
    2) Swing

    Obviously the only movement we need in this kind of clocks is the rotative movement.

    One of the reasons of the swing is some oscilation in the building. For example, when the wind blows strongly (in high buildings), this swinging movement appears in the torsion pendulum.

    But sometimes we can observ this swing movement without any external cause.

    Can anyone provide some insight into the cause of this oscillation in the absence of any movement on the clock?.

    Thank you very much in advance.

    Kind regards,
    Miguel
    ;););)
     
  2. Tony10Clocks

    Tony10Clocks Registered User

    Aug 10, 2010
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    Hello cucoclock, A couple of reasons could be the balls are not weighted evenly, ( very unlikley unless some has changed the balls, maybe someone has cleaned them and split the casing of the balls and taken out the weight ). Or the centre hook where the block slots in is bent,
    Tony
     
  3. cucoclock

    cucoclock Registered User

    Jul 17, 2005
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    Hi Tony,

    Thank you for your answer.

    I think you are right, if balls weight is not correct the fork can move laterally the suspension producing swing.

    Kind regards,
    Miguel
     
  4. John Hubby

    John Hubby Senior Administrator Emeritus
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    Both of these reasons are correct and will create what I call "pendulum wobble". A third reason is that the suspension spring may not be perfectly centered in the top or bottom blocks, which causes the spring to be distorted under the weight of the pendulum.
     
  5. shutterbug

    shutterbug Moderator
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    Oct 19, 2005
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    Also not yet mentioned is the necessity of a good solid bench, table, etc. to set the clock on. If the table is not stable, the pendulum will surely influence it and get it rocking.
     

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