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  • Pendulum Energy

    Discussion in 'The main mechanical design forum' started by greenguy, Nov 11, 2010.

    1. greenguy

      greenguy Member

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      Working on a project to convert the motion of a pendulum into rotary motion of a shaft. The shaft the pendulum swings on obviously goes back & forth, so the challenge is converting this bidirectional motion into a constant, single direction on a different shaft. Any thoughts / insight on the best gearing configuration to do this would be appreciated. Thanks,

      - greenguy
       
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    3. frippdesign

      frippdesign New Member

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      It's called an internal combustion engine...think pendulum as a con rod, think rotational movement as a crank shaft.

      Also think nodding donkeys which extract oil out of the ground.

      PS, I'm not a designer or engineer either :)
       
    4. cwarner7_11

      cwarner7_11 Well-Known Member

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      There are actually a number of different approaches to this problem, and which might be appropriate to your particular application would depend on other external constraints. The easiest to implement would likely be a ratchet and pawl arrangement. Think of your common ratchet driver for tightening/loosening nuts and bolts (you may even want to buy a cheap one and take it apart to figure out how it works). Or one could possibly use two mating plates with ramped "teeth" that allow slippage in one direction and joint movement in the other direction. Possibly one would want to consider a modification of the basic Geneva mechanism.
       
    5. greenguy

      greenguy Member

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      Thanks for the input on this. I was thinking in terms of a ratchet gear, so good to get confirmation. Not sure what the Geneva Mechanism is, but I'll be sure to check that out. Really good input.
       
    6. maniacal_engineer

      maniacal_engineer Well-Known Member

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      better than a pawl (with dead spots due to a finite number of teeth) try a sprague clutch or one of these roller clutches
      http://www.mcmaster.com/#roller-clutches/=a17y0p
      put two on the shaft, one facing each way, with an extra idler gear on the output from on of them and you will have constant output in one direction, but the velocity will have bumps in it as the pendulum slows and reverses.
       

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