- Measure the belt tension with a belt tension gauge.
- Do not attempt to tension the belt without proper testing tools.
- If the existing belt shows signs of excessive wear, it should be replaced.
Fan Pulley and Motor Pulley Alignment
- For proper belt seating, ensure the centerline of the pulleys are aligned. Use a straight edge to verify pulley alignment.
- Verify that all pulley setscrews are secure.
Best Practices for Installing Belt
- Measure the distance (inches) from the center shaft of the motor to the center shaft of the blower wheel.
- Round the distance to the closest value. If evenly divided, round down. For example, 20 ½ is rounded down to 20 inches.
- Set the bottom O-ring of the belt tension gauge to that value. For example, slide the O-ring down to the 20-inch mark or notch on your gauge.
- Set the top O-ring at zero (0). (Slide the O-ring to the base.)
- Set a straight edge across the top of the belt. Deflect the belt until the bottom O-ring is in the same plane as the straight edge.
The top O-ring will have moved up the gauge and show the amount of force used. For example, say 7 pounds.
Measure the diameter of the smaller pulley. The diameter of the smaller pulley determines pressure to the belt that should be applied to the belt.
- Using a deflective force chart, find the value your tension gauge registered and compare it with the diameter of the smaller pulley. For example, if you are using a BX type belt, your tension gauge registered 10 pounds of force, and the smaller pulley is 5 inches in diameter, then the belt tension is in the acceptable range.
If the belt cannot be properly tensioned, install a longer or shorter belt, as necessary
To properly use this document, the technician will need a belt tensioning tool that utilizes a spring depressor that reads in pounds and fractions of an inch. Do not attempt to tension the belt without the proper testing tools. Failure to properly tension the belt may cause bearing failure or permanent damage to the motor.
First: Measure the distance from center shaft of the motor to the center shaft of the blower wheel.
Next: Measure the small pulley diameter
The distance between the center shafts in inches. Round to the closest
distance provided. If evenly divided round down.
- The diameter of the smaller pulley determines the applied pressure to the belt. Select your diameter size to find the pressure range to use.