Effects of bearing preload

The primary benefits resulting from preload include but are not limited to:
  • enhanced stiffness
  • reduced noise levels
  • improved shaft guidance
  • compensation for wear and settling
  • extended bearing service life

Enhanced stiffness

Bearing stiffness is defined as the ratio of the force acting on the bearing to the elastic deformation in the bearing. The elastic deformation caused by a load in preloaded bearings is smaller for a given load range than for bearings that are not preloaded.

Reduced noise levels

As operating clearance in a bearing decreases, guidance of the rolling elements in the unloaded zone improves, which reduces noise levels in operation.

Improved shaft guidance

Preloaded bearings provide more accurate shaft guidance because preload provides a higher degree of stiffness, which limits the ability of the shaft to deflect under load. For example, preloading the ring and pinion bearings in a differential results in increased stiffness, which keeps gear mesh accurate and constant. This minimizes dynamic forces and reduces noise levels, which can extend the service life of the gears.

Compensation for wear and settling

Wear and settling in a bearing arrangement in operation increases the clearance. This clearance can be compensated for with preload.

Extended bearing service life

In certain applications, an optimum preloaded bearing arrangement (→ Selecting the correct preload) can enhance operational reliability, provide more favourable load distribution in the bearings and extend bearing service life.
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