That is, a shaft or inner ring rotating application like an electric motor will use a press fit on the shaft and a loose fit on the housing. A housing or outer ring rotating application like a wheel hub will employ the reverse: a loose fit on the shaft and a press fit on the housing. This will greatly reduce the chances of creep or a loosened fit during operation.

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A slight press fit will generally help prevent creep, but an excessive press fit will eliminate the bearing internal clearance and cause a rise in operating temperature that can lead to early failure. Press fits will naturally make installation of the bearing more difficult and susceptible to damage, but with proper care, most problems can be avoided.

A loose fit allows for easy installation, but too loose of a fit may allow the bearing ring to slip or creep on the shaft or in the housing. Creep can cause excessive wear or vibration and in the worst cases lead to ring fracture or bearing seizure.

3 types of bearing fits

Determining proper shaft and housing fits is critical to ensure long bearing life. The fit, or amount of interference that exists between mating components (such as the shaft and bearing bore), can be devised into three categories: loose (slip), transition, and press (tight). For more information on recommended shaft and housing fits, please download this catalog excerpt.

The type of fit required varies on a number of factors such as load, operating temperature, bearing type, and shaft or housing material. A good rule of thumb for most applications is to use a press fit on the rotating component.