9
LV Motors/Machine Instructions 10-2000
TROUBLE
CAUSE
WHAT TO DO
Motor vibrates
Motor misaligned
Realign.
Weak support
Strengthen base.
Coupling out of balance
Balance coupling.
Driven equipment unbalanced
Rebalance driven equipment.
Defective bearings
Replace bearings.
Bearings not in line
Line up properly.
Balancing weights shifted
Rebalance motor.
Contradiction between balancing of
Rebalance coupling or motor
rotor and coupling
(half key – full key)
Polyphase motor running single phase Check for open circuit.
Excessive end play
Adjust bearing or add shim.
Scraping noise
Fan rubbing fan cover
Remove interference.
Fan striking insulation
Clear fan.
Motor loose on bedplate
Tighten holding bolts.
Noisy operation
Airgap not uniform
Check and correct bracket fits or bearing.
Rotor unbalance
Rebalance.
Hot bearings general
Bent or sprung shaft
Straighten or replace shaft.
Excessive belt pull
Decrease belt tension.
Pulleys too far away
Move pulley closer to motor bearing.
Pulley diameter too small
Use larger pulleys.
Misalignment
Correct by realignment of drive.
Hot bearings ball
Insufficient grease
Maintain proper quality of grease in bearing.
Deterioration of grease or lubricant
Remove old grease, wash bearings thoroughly in
contaminated
kerosene and replace with new grease.
Excess lubricant
Reduce quantity of grease, bearing should not be
more than 1/2 filled.
Overloaded bearing
Check alignment, side and end thrust.
Broken ball or rough races
Replace bearing, first clean housing thoroughly.