BRINELLING

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

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.

Axial stiffness of a bearing at a given (axial) preload is:

Axial stiffness (Newton / meter)    =                   
Change in preload force (N) / Corresponding change in displacement (m)             =          Δf_a/ Δδ
                                                                 

The stiffness of a preloaded bearing assembly is determined by the inverse slope of the preload vs. displace ment curve for the bearings used (see page 32).