Axial Rigidity

Rigidity RA of an angular contact ball bearing is the external axial load causing 1 micron displacement (daN/mm).
Ra of a bearing pair or set can also be defined as the ration between the limiting axial load Pd and the bearing axial deflection a2. Axial rigidity remains practically constant until external load is great than off load Pd.
Axial rigidity Ra varies as contact angle and bearing preload vary.
Preloaded bearing deflection curves are use to plot axial rigidity and the limiting axial load as follows:

 

Radial Rigidity
Angular contact ball bearing radial rigidity “Rr” too, varies with contact angle and preload; unlike axial rigidity however, radial rigidity decreases as contact angle increases and changes markedly as a function of the ration between axial and external loads applied to the bearing.
The radial rigidity of a back-to-back or face-to-face bearing set can be empirically calculated as follows: