NEWS CENTER

Malfunctions in electric motor bearings

2017-03-15

On machines with ring lubrication, the cause of excessive heating of bearings can be insufficient oil supply as a result of slow rotation or complete standstill of the lubrication rings. Lubrication rings can stop due to oil thickening. Inadequate oil supply can also be the result of jammed oil rings, improperly shaped oil rings, or low oil level in the bearings.

To correct this problem, replace the thick oil with new oil, check the oil level at the oil sight glass, replace the light rings with heavier rings, and correct or replace damaged rings.

For machines with forced lubrication, bearings can overheat as a result of clogged oil pipe or oil filter and contamination of oil in the bearings. This can be remedied by flushing the whole oil system, cleaning the oil chambers, changing the oil and sealing the bearings.

Bearings can overheat due to improper alignment of the motor with the production machinery, and also due to small clearance between the shaft journal and the liner. The liner is considered well aligned if the running-in marks are evenly distributed over the entire length of the bottom liner in an arc of 25-30°. 

Bearing heating is also affected by inadequate oil grade, poor liner filling, distortion of the motor shaft or crankshaft journals, and the presence of axial thrust on the bearings. The latter is caused by axial displacement of the rotor or insufficient clearances between the bearing shells and the shaft flanges, which prevents free thermal expansion.