NEWS CENTER

Knowledge of bearing pre-tensioning

2016-12-25

Rolling bearings are generally used with proper internal clearance during operation. However, depending on the application, an axial load may be applied to the bearing in advance to make it bear negative internal clearance. This method is called pre-tensioning, it is mostly applicable to angular contact ball bearings or tapered roller bearings.

Purpose of pre-tensioning

● Improve the axial and radial positioning accuracy, reduce the runout of the shaft, and improve the rotation accuracy.

● Improve bearing rigidity and gear meshing accuracy;

● Inhibit rolling, rotating and orbiting of the rolling elements to reduce abrasion;

● Prevent abnormal bearing noise caused by vibration and resonance;

● Ensure the relative positions of the rolling elements and the rings are correct.

Pre-tightening method

There are two methods to apply preload: positioning preload and constant pressure preload.

Comparison of positioning pre-tensioning and constant pressure pre-tensioning:

● When the preload force is the same, the axial displacement of the positioning preload bearing is small, and it is easy to obtain high rigidity;

● Constant pressure pre-tensioning can use the spring to absorb changes in load and shaft expansion and contraction caused by the temperature difference between the shaft and the housing during operation. Therefore, the pre-tensioning force changes little and a stable pre-tensioning force can be obtained;

● Positioning pre-tensioning can apply large preloading force.

Therefore, when high rigidity is required, positioning pre-tensioning should be adopted. For thrust bearings that require high-speed rotation, prevention of axial vibration, and thrust ball bearing for horizontal shafts, constant pressure pre-tensioning should be used.