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"Contraption" Project: Scratch build motor belt/chain drive w/ variable for/rev speed

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by adambowersva, Apr 19, 2010.

  1. Sceadwian

    Sceadwian Banned

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    Keep in mind such a break will not be able to be engaged at speed and will likely slip slightly before it actually engages.
     
  2. Gary B

    Gary B New Member

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    Given that such a device is only intended to hold rather than stop, that it will only attempt to engage once power to the motor has been removed, and the load is attempting to reverse the direction of the gear train, you should be able to drop the paw when the holding gear is almost at a complete stop. An accuracy of ± one tooth should be achievable by just adjusting the strength of the spring and the distance the paw has to travel to engage.
     
  3. Sceadwian

    Sceadwian Banned

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    That relys an awful lot on precision timing of a mechanical device Gary, if the timing fails via some unforseen event and the paw bounces once it may be enough to keep it bouncing as the load accelerates out of control. I personally wouldn't trust something like that. The only electric brakes I've ever seen are in 1/4 ton industrial chain hoists, those work via a clutch and a mechanical gear lock together. The clutch is there to keep the load from gaining any kind of momentum until it can catch. For lighter loads the mechanical lock often isn't even needed and you can simply rely on the clutch, depends whole on the situations and the minds of the maker.
     
  4. dave

    Dave New Member

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  5. Gary B

    Gary B New Member

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    That would relate more to the shape of the paw verses the shape of the tooth than anything else but, yes that would be a consideration in the design. You might want a flywheel/brake that controls the maximum speed and the holding paw to engage a gear that moves 1/10 that speed.
     

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