Cyndi Nyberg
Former EASA Technical Support Specialist

Editor's Note: This article is similar to a February 2010 Currents article titled "Preloading roller bearing motors for no-load run testing." These two articles complement and supplement each other.

Ball and sleeve bearing motors can always be test run without any type of external load on the motor and bearings. 

However, when repairing a motor equipped with roller bearings that is used in an application with a radial load, such as a belted load, it is not advisable to perform the standard no-load test run for any length of time. Yet the no-load test run is a crucial step in the repair process to ensure proper operation. Without that radial load, the bearings can be damaged. This article will describe two ways to put a load on the shaft of a motor and therefore the roller bearing, so that it can be test run to ensure that it has been properly repaired. 

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