A belt-driving motor failed, and was promptly replaced with the same model. The failed motor went out for repair, and came back with new a new drive-end bearing. It passed all of the motor shop’s tests, so was put back into the stockroom. It would not stay there for long. After three weeks of operation, the drive-end bearing of the replacement motor failed. It got sent to the motor shop, and the repaired original replaced it. After a few weeks, they swapped places yet again! In each case, the motor was laser-aligned. The lubrication practices were thoroughly reviewed and aren’t the culprit.
What might be causing that bearing failure?
In the case of circulating current, both bearings will show pitting and other evidence. Such evidence wasn’t mentioned by the motor shop.
That the drive-end bearing, not the thrust end bearing, fails is a good clue this is a load problem. Something is adding force the bearing isn’t designed to handle. Look at how the motor is positioned relative to its load. If the belt points off at an angle, move the motor or load to get perpendicularity. How long is the pulley assembly? If it’s too “overhung” it’s putting downward force (weight) on that bearing; use a shorter assembly and/or install a rolling-element bearing.
