Basic rating life

The basic rating life of a bearing according to ISO 281:2007 is

Basic rating life
Perform calculation

If the speed is constant, it is often preferable to calculate the life expressed in operating hours using

Basic rating life in hours

L10=basic rating life (at 90% reliability) [millions of revolutions]
L10h=basic rating life (at 90% reliability) [operating hours]
C=basic dynamic load rating, [kN]
P=equivalent dynamic bearing load [kN]
n=rotational speed [r/min]
p=exponent of the life equation
= 3 for ball bearings
= 10/3 for roller bearings
Table 1 provides commonly used conversion factors for bearing life in units other than million revolutions.
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