Size & Basic Load Ratings

The following relation exists between bearing load and rating fatigue life:

For ball bearings:
For roller bearings:

where

L 10	Rating fatigue life (10 6 rev)
P	Bearing load (equivalent load) (N)
C	Basic dynamic load rating (N)

For radial bearings, C is written C r
For thrust bearings, C is written C a

In the case of bearings that run at a constant speed, it is convenient to express the fatigue life in terms of hours. In general, the fatigue life of bearings used in automobiles and other vehicles is given in terms of mileage . By designating the rating fatigue life as L h (h), bearing speed as n (rpm), and fatigue life factor as fh, the following relations are obtained:

For ball bearings:
For roller bearings:

If the operating conditions are the bearing load P and speed n, and the fatigue life is Lh , C can be calculated using these equations above.