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Pulley Size calculations

  1. May 31, 2004 #1
    can you help?

    I have a restaurant exhaust fan with a drive pulley of 2" and a shaft pulley on the fan of 7 and 3/4 inches. The belt that fits this is 21/32" width. The belts keep wearing out very quickly. I think that larger pulleys would solve the problem. If I doubled the size of the drive pulley, what size would I need to make the driven (fan) pulley to keep the same RPM (about 700 to 750)

    Thanks for the help!

  2. jcsd
  3. May 31, 2004 #2


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    Double. You knew that --- be sure you can get the appropriate belt length.
  4. May 31, 2004 #3

    I think the real problem here is not pulley size, but that the belt is too tight, or the berrings in the fan have gone bad; and the pulleys are no longer aligned with each other.

    700-750RPM for an exhaust fan does seem a bit slow - I usually see them running at 1350RPM, but direct drive. Increasing the drive pulley would, of course, increase the RPM of the fan.
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