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Power required to rotate

  1. Dec 2, 2009 #1
    Hi All,

    Cable drum, OD-50" weight abt 3 ton.. support by shaft horizontally.Both end of shaft is mounted on bearing. now i need to select electrical motor to rotate the this drum.
    drum need to rotate constant 30 rpm speed..
    please some one help to calculate the power required to rotate.
  2. jcsd
  3. Dec 2, 2009 #2
    Zero horsepower, discounting friction and external forces on the drum.
  4. Dec 2, 2009 #3
    You will need some power in order to accelerate the drum up to 30rpm. Not only that, but as the cable is taken off the drum its moment of gyration will change.

    You can determine the power required to accelerate the drum using newtons second law to find the drums kinetic energy at 30rpm. In order to maintain that speed you will need to know how the drums mass and geometry changes as cable is removed and the friction inflicted on the drum.
  5. Dec 3, 2009 #4

    Thanks for reply..
    actually, drum rod is supported by both end needle bearings....because using bearing, HP required to rotate the drum get reduced or not...how much %..how to calculate that..
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