Ball bearings life is related to load and speed of rotation, and this relationship must be considered when selecting bearings for various speed and life requirements. Bearing life has been determined by testing at bearing manufacturers. Bearing fatigue life has been determined to vary inversely with the third power of the applied load. This is expressed as follows:

Lf =Ca / [Sf X P X Hf ]

Where:

Lf = Life factor

Ca= Dynamic Load Rating (manufacturer specified) or Ct for thrust

P = Applied load (Effective or equivalent load may be used)

Sf = Speed factor (manufacturer specified)

Where determining the required basic dynamic load rating determines the bearing choice, the follow equation applies:

To Calculate the allowable load your bearing will support under the conditions of speed and life:

Pa = Ca (or Ct) / [ Sf X Lf X Hf ]

Pa = Load allowed for conditions