Gravity Escapement Escape wheel RPM

Discussion in 'Clock Construction' started by dandydude, Mar 14, 2018.

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  1. dandydude

    dandydude Registered User

    Nov 30, 2014
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    Hello,

    I was studying double 3 legged gravity escapements. With a seconds pendulum does it take 6 seconds or 12 for an entire rotation of the escape wheel? I am not able to figure that out...

    Dandydude
     
  2. Phil Burman

    Phil Burman Registered User

    Mar 8, 2014
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    As the pendulum is 1 beat per second and the escape wheel moves every beat and moves 6 times for one revolution it must be 6 seconds per revolution.

    Phil
     
  3. dandydude

    dandydude Registered User

    Nov 30, 2014
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    Dear Phil,
    Thanks for that...
    In a graham dead beat style, each beat moves half a tooth forward right? (30 tooth Escape Wheel + 1 second pendulum = 1 RPM of Escape Wheel)
    Why would it be different in gravity escapements? Why would it move 1 tooth per beat and not half tooth?
    I have been finding some conflicting information online.
     
  4. Phil Burman

    Phil Burman Registered User

    Mar 8, 2014
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    With a dead beat escapement each pallet operates on every one of the 30 teeth the escapement moves only half a tooth spacing per beat., whereas each three legged escapement in the double gravity escapement operates only on its corresponding pallet. It's effectively two separate 3 tooth escapements.

    Phil
     
  5. tok-tokkie

    tok-tokkie Registered User

    Nov 25, 2010
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    Double 3-legged gravity escape wheel moves 60° each event so with a 1-sec pendulum you need a 10:1 gear reduction to drive a seconds hand.
     
  6. Phil Burman

    Phil Burman Registered User

    Mar 8, 2014
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    The confusion may be because a single six legged escapement will rotate once every 12 beats whereas a double three legged every 6 beats.

    Phil
     
  7. dandydude

    dandydude Registered User

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    Thanks for that tok-tokkie...
    1:10 wheel would be the fourth wheel... this would end up being larger than the 3rd wheel which is usually a 1:7.5... this is bit inconvenient, don't you think?

    Thanks a ton
    Dandydude
     
  8. dandydude

    dandydude Registered User

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    That makes it so much more clear. Thanks Phil...

    regards
    Dandydude
     
  9. tok-tokkie

    tok-tokkie Registered User

    Nov 25, 2010
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    I suggest you read my 30-legged gravity escape thread. I give a detailed illustrated description of how a gravity escape works. There is a link to the Trinity College clock site which has an animation of a double 3-legged in action. It also has very thorough mathematical analysis of the dynamics of the escape. 30-Legged Gravity Escape Clock
     
  10. dandydude

    dandydude Registered User

    Nov 30, 2014
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    Dear tok-tokkie,

    Thanks for that. I will certainly study your thread...

    Thanks & regards
    Dandy
     

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