A comprehensive engineers' reference source for radial ball bearings and thrust ball bearing




Typical inner race misalignment of a preloaded bearing pair as shown from a MicroTorqueTM torque analysis where inner rings are rotated during test. Note that almost all preloaded bearing assemblies exhibit this characteristic to some extent. The test is very sensitive and can detect misalignment of <.0001 inch.
Torque trace of misaligned bearing(s)
Brinelling is shown as a series of regularly spaced spikes with negative leading edge.

The ball falls into the brinelled depression in the raceway before climbing out. Therefore torque decreases as brinelling is encountered. Severe brinelling may cause multiple spikes where the leading edge can be positive, since raceway becomes rippled from damage.

Torque trace of brinelled bearing(s)
Contamination is shown as a series of irregularly-spaced spikes with positive leading edge.

The ball has to climb over the contaminant before falling off the back side. Therefore torque increases as contaminant is encountered.

Torque trace of contaminated bearing(s)

General Note: An analysis of periodic factors of the torque can show different contributions from bearing cage, grease and other elements.To interpret these results, it is necessary to know internal bearing characteristics, and over-analysis is cautioned.

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