The main purposes and representative examples of preload are as follows:

⑴ Improve the guiding accuracy of bearings. Spindle bearings of machine tools, bearings for measuring instruments.

⑵ Improve rigidity. Spindle bearings of machine tools, bearings for pinions of automobile differential mechanisms.

⑶ Reduce vibration and noise during operation. Bearings for small motors.

⑷ Prevent sliding of rolling elements relative to the inner and outer raceways caused by inertia moment. High-speed rotating angular contact ball bearings, thrust ball bearings.

⑸ Compensate for wear and sinking during operation, and extend service life.

⑹ Keep rolling elements and bearing rings in the correct position. Thrust ball bearings and thrust spherical roller bearings mounted on horizontal shafts.

Shaft guiding accuracy

Axles supported by preloaded bearings have higher guiding accuracy because the flexure capacity of the shaft under load is limited by the preload. Preloaded differential bearings have higher guiding accuracy and higher rigidity, which means that accurate and constant meshing can be maintained, and the additional dynamic force is small, so the running noise is low and the meshing gears have a longer life. Bearing stiffness The stiffness of a bearing is defined as the ratio of the force acting on the bearing to the amount of elastic deformation of the bearing. Within a certain load range, the elastic deformation of a preloaded bearing is smaller than that of a non-preloaded bearing.

Low-noise operation

The smaller the bearing running clearance, the better the guidance of the rolling elements in the load-free zone, and the lower the noise when the bearing is running. Compensation for wear and sinking During operation, wear and sinking of the bearing increase the clearance, but this can be compensated by preloading.

Longer service life

In some cases, bearings are arranged in pairs and preloaded to improve operating reliability and extend service life. Because the appropriate amount of preloading can improve the load distribution of the bearing, it can increase its service life.