BASIC LOAD RATINGS
The basic dynamic load rating "C" is defined as the constant bearing load which will give an ISO basic rating life, as defined above, of one million revolutions. It refers to pure radial load for radial bearings and to pure axial load for thrust bearings.
Similarly the basic static load rating "Co" is defined as the static load which corresponds to a total permanent deformation of the rolling elements and race ways at the most heavily stressed contact point of 0.0001 times the diameter of the rolling elements. It refers to pure radial load for redial bearings and to pure axial load for thrust bearings.
The relationship between the basic rating life, the basic dynamic load rating and the bearing load can be presented in the ISO equation as
- L 10 = (C/p)p
- L 10 = Basic rating life in millions of revolutions
- C = Basic dynamic load rating, N
- p = Equivalent dynamic bearing load, N
- p = Exponent for the life formula
- = 3 for ball bearings
- = 10 / 3 for roller bearings
Until now we have only considered the pure radial load or the pure axial load. In practice however, both radial and axial loads may act on a bearing simultaneously. It is therefore necessary to calculate the equivalent dynamic bearing load.
This is defined as that hypothetical load, constant in magnitude and direction, which when applied would have the same influence on bearing life as the actual loads to which the Bering is subjected.