MK Plastics RBK IO&M - Manual (Page 8)

8
Motor Service
Should the motor prove defective within one-year period, contact M.K. Plastics directly, or your nearest motor service
representative.
Changing Shaft Speed
All belt driven fans with motors up to and including 3 hp (182T max.) are equipped with variable pitch motor pulleys. To change
the fan speed, perform the following:
1. Loosen setscrews on driver (motor) pulley and remove key, if equipped.
2. Turn the pulley rim to open or close the groove facing. If the pulley has multiple grooves, all must be adjusted to the
same width.
3. After adjustment, inspect for proper belt tension and alignment.
Speed Reduction
Open the pulley in order that the belt rides deeper in the
groove (smaller pitch diameter).
Speed Increase
Close the pulley in order that the belt rides higher in the
groove (larger pitch diameter). Ensure that the RPM limits
of the fan and the horsepower limits of the motor are
maintained, which can be read on the motor nameplate.
Pulley & Belt Replacement
1. Remove pulleys from their respective shafts.
2. Clean the motor and fan shafts.
3. Clean bores of pulleys and coat the bores with heavy oil.
4. Remove grease, rust, or burns from the pulleys and shafts.
5. Remove burrs from the shaft by sanding.
6. Place fan pulley on the fan shaft and motor pulley on its shaft. Damage to the pulleys can occur when excessive force
is used in placing the pulleys on their respective shafts.
7. Tighten in place.
8. Install belts on pulleys and align as described in the Belt and Pulley Installation section.
Troubleshooting
Problem and Potential Cause
Low Capacity or Pressure
• Incorrect direction of rotation. Make sure the fan rotates in same direction as the arrows on the motor or drive belt
assembly.
•
Poor fan inlet conditions. There should be a straight clear duct at the inlet.
• Improper
wheel alignment.
Excessive Vibration and Noise
•
Damaged or unbalanced wheel.
•
Belts too loose; worn or oily belts.
•
Speed too high.
• Incorrect direction of rotation. Make sure the fan rotates in same direction as the arrows on the motor or drive belt
assembly.
•
Bearings need lubrication or replacement.
•
Fan surge or incorrect inlet condition.
Overheated Motor
• Motor
improperly wired.
• Incorrect direction of rotation. Make sure the fan rotates in same direction as the arrows on the motor or drive belt
assembly.
•
Cooling air diverted or blocked.
• Improper
inlet clearance.
•
Incorrect fan RPM.
• Incorrect
voltage.
Overheated Bearings
•
Improper bearing lubrication.
•
Excessive belt tension.