Rolling bearing preloading methods can be divided into radial preloading method and axial preloading method.

1. Radial preload method

Radial jacking method is often used in tapered bore bearings bearing radial load, a typical example is double row precision short cylindrical roller bearings.The radial negative clearance can be obtained by adjusting the axial position of the bearing relative to the taper journal with the nut, which is widely used in machine tool spindles and jet engines, so that the inner ring has proper expansion.

2. Axial preload method

Axial preloading method can be divided into positioning preloading and fixed pressure preloading.

In the positioning preload, the appropriate preload can be obtained by adjusting the size of the bushing or gasket.It can also be adjusted properly by measuring or controlling the starting friction torque.Also can be directly used to adjust the preloading amount of a pair of double bearings to achieve the purpose of preloading, this time generally do not need to be adjusted by the user.In short, the relative position of bearings that are preloaded axially will not change when they are used.

Constant pressure preloading is to use spiral spring, disc spring and so on to make the bearing get the proper preloading method.The rigidity of the preloaded spring is generally much smaller than the rigidity of the bearing, so the relative position of the constant pressure preloaded bearing will change in use, but the preloaded amount is roughly the same.

The comparison between positioning preloading and constant pressure preloading is as follows:

(1) when the preloading amount is equal, positioning preloading has a greater effect on the increase of bearing rigidity, and the impact of the rigidity change on bearing load is much smaller when the positioning preloading is equal.

(2) positioning preload in use, due to the axial length difference caused by the temperature difference between the shaft and the bearing seat, the radial expansion caused by the temperature difference between the inner and outer ring and the displacement caused by the load, the preload will change;And constant pressure preload in use, preload changes can be ignored.

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