Static bearing loads

The basic static load rating C0 is used in calculations when the bearings are to
  • rotate at very slow speeds (n < 10 r/min)
  • perform very slow oscillating movements
  • be stationary under load for certain extended periods.
It is also most important to check the safety factor of short duration loads, such as shock or heavy peak loads that act on a bearing, whether it is rotating (dynamically stressed) or at rest.
The basic static load rating as defined in ISO 76:1987 corresponds to a calculated contact stress at the centre of the most heavily loaded rolling element/raceway contact of
  • 4 600 MPa for self-aligning ball bearings
  • 4 200 MPa for all other ball bearings
  • 4 000 MPa for all roller bearings.
This stress produces a total permanent deformation of the rolling element and raceway, which is approximately 0,0001 of the rolling element diameter. The loads are purely radial for radial bearings and centrically acting axial loads for thrust bearings.
Verification of the static bearing loads is performed checking the static safety factor of the application, which is defined as:
s0 = C0/P0

C0=basic static load rating [kN]
P0=equivalent static bearing load [kN]
s0=static safety factor
The maximum load that can occur on a bearing should be used in the calculation of the equivalent static bearing load. Further information about the advised values for the safety factor and its calculation can be found in the section Selecting bearing size using the static load carrying capacity.
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