What are the benefits of preload for bearings?

The so-called bearing clearance refers to the amount of movement when the bearing is not mounted on the shaft or the bearing box, when the inner ring or the outer ring is fixed on one side, and then the unfixed side is moved in radial or axial direction.

The so-called bearing clearance, that is, the bearing is not installed in the shaft or bearing box, the inner ring or the outer ring will be fixed on one side, and then it is not fixed on the side of the radial or axial movement when the amount of movement.

According to the direction of movement, can be divided into radial clearance and axial clearance. Clearance for the use of bearings is also very important.

Six things to know about bearing clearance:

1、The size of the running clearance (called working clearance) has an effect on the rolling fatigue life, temperature rise, noise, vibration and other performance of the bearing.

2、When measuring the clearance of the bearing, in order to get a stable measurement value, the bearing is generally subjected to a specified measurement load. Therefore, the measured value obtained than the real clearance (called as the theoretical clearance), that is, increase the measured load generated by the elastic deformation. For roller bearings, due to this elastic deformation is small, can be ignored.

3, the internal clearance of the bearing before installation is generally expressed by the theoretical clearance.

4, from the theoretical clearance minus bearing installed in the shaft or shell due to the expansion or contraction of the collar produced by the interference fit clearance is called “installation clearance”. In the installation clearance plus or minus the bearing internal temperature difference due to the amount of size change after the clearance is called “effective clearance”.

5, bearing installation with mechanical bearing a certain load placed on the clearance, that is, the effective clearance plus bearing load generated by the amount of elastic deformation so as to be called “working clearance”.

6, when the working clearance for micro-negative value, bearing fatigue life is the longest but with the increase of negative clearance fatigue life with a significant decline.

Therefore, the choice of bearing clearance, generally make the working clearance is zero or slightly positive is appropriate. In addition, need to improve the rigidity of the bearing or need to reduce the noise, the working clearance to further take the negative value, and in the bearing temperature rise is intense, the working clearance to further take the positive value, etc., but also must be based on the use of conditions to do specific analysis.

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