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How to Test the Speeds of Pulleys

Two variables you can use to determine the speed of pulleys that are used to drive an object include the gearing ratio and RPM speed. When two pulleys are being used, one is the drive pulley which is attached to a motor. The other is the object pulley, which is attached to the object being driven. To determine pulley speed you need to obtain the values used for each variable.

Instructions

Gearing Ratio
- 1
  Measure the width of the drive pulley with the tape measure. Make a note of the measurement, such as 8 inches.
- 2
  Measure the width of the object pulley and make a note of the measurement, such as 3 inches.
- 3
  Divide the width of the object pulley by the width of the drive pulley for a result of 2. The gearing ratio of your pulleys is 2-to-1.
RPM Speed
- 4
  Determine the RPM drive speed of the motor for the drive pulley. Make a note of the RPM drive speed, such as 2,000.
- 5
  Measure the width or diameter of the drive pulley with the tape measure. Note the measurement, such as 4 inches.
- 6
  Measure the width or diameter of the object pulley. Note the measurement, such as 8 inches.
- 7
  Multiply the RPM drive speed by the diameter of the drive pulley for a result of 8,000. Divide 8,000 by 8 for a result of 1,000 RPM. This is the speed of your pulleys.

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