The preloading method is divided into two categories: radial preloading method and axial preloading method, which are described as follows.

1. Radial preloading method:

Radial jacking method is mostly used in tapered bore bearings bearing radial loads, a typical example is double row precision short cylindrical rollers For sub-bearings, the axial position of this bearing relative to the tapered journal is adjusted by a nut, so that the inner ring has a suitable expansion amount to obtain a radial negative clearance. This method is mostly used in machine tool spindles and jet engines.

2. Axial preloading method:

Axial preloading method can be roughly divided into two types: positioning preloading and constant pressure preloading. In the positioning preload, the appropriate preload can be obtained by adjusting the size of the bushing or washer; the appropriate preload can also be adjusted by measuring or controlling the starting friction torque; the preload can also be directly adjusted by using the To achieve the purpose of preloading, the user generally does not need to adjust it again at this time. In short, for any bearing that has been axially preloaded, its relative position will definitely not change during use. The constant pressure preload is a method of using a coil spring, a disc spring, etc. to make the bearing get a proper preload. The rigidity of the preload spring is generally much smaller than the rigidity of the bearing, so the relative position of the bearing with constant pressure preload will change during use, but the preload amount remains roughly the same.

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

(1) When the preload is equal, the effect of positioning preload on the increase of bearing rigidity is greater, and the positioning Changes in stiffness during preload also have much less effect on bearing loads.

(2) During the use of positioning preload, 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 rings, and the displacement caused by the load, etc. The influence of the preload will change the preload; while the constant pressure preload is in use, the change of the preload can be ignored.