1. The selection of the tolerance grade is related to the tolerance grade of the shaft or bearing seat hole matched with the bearing and the bearing accuracy. For the shaft matched with the P0 grade precision bearing, the tolerance level is generally IT6, and the bearing seat hole is generally IT7. For occasions with higher requirements on rotation accuracy and running stability (such as motors, etc.), the shaft should be IT5 and the bearing seat hole should be IT6.

2. The selection of the tolerance zone The equivalent radial load P is divided into several cases, such as light normal load and heavy load, and the relationship between it and the rated dynamic load C of the bearing is: light load 0.06C normal load 0.06C<P&le; 0.12C＜P1) Shaft tolerance zone For the tolerance zone of the shaft on which the radial bearing and angular contact bearing are installed, refer to the corresponding tolerance zone table. For most occasions, the shaft rotates and the radial load direction does not change, that is, when the bearing inner ring rotates relative to the load direction, a transition or interference fit should generally be selected. When the shaft is stationary and the radial load direction is unchanged, that is, when the inner ring of the bearing is stationary relative to the load direction, transition or small clearance fit can be selected (too much clearance is not allowed).

2) Tolerance zone of housing hole For the tolerance zone of housing bore for radial bearings and angular contact bearings, refer to the corresponding tolerance zone table. When selecting, pay attention to avoid clearance fits for outer rings that oscillate or rotate in the direction of load. The size of the equivalent radial load also affects the fit selection of the outer ring.

3) Selection of bearing seat structure The bearing seat of the rolling bearing generally adopts an integral structure unless there is a special need. The split bearing seat is only used when it is difficult to assemble, or when the advantage of convenient assembly becomes the main consideration. , but it cannot be used for tight or more precise fits, such as K7 and tighter fits than K7, and for housing holes with tolerance class IT6 or higher, split housings must not be used.