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Help with gear ratio

  1. Jan 21, 2007 #1
    I have a 8-1/2 inch drive pulley turning at 340 rpm. I want to have it drive a pulley and want that pulley, the driven pulley, to turn at 200 rpm. What is the formula to figure out what size pulley I need. Please help:smile: :smile:
  2. jcsd
  3. Jan 21, 2007 #2


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    Science Advisor
    Gold Member

    The product of speed and diameter will be the same on both driven pulleys.
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