The radial clearance of a double row deep groove ball bearing refers to the amount of movement that one ring is fixed and the other ring moves from one extreme position to the other extreme position in the direction perpendicular to the axis of the double row deep groove ball bearing. . Whether the bearing clearance is selected correctly or not has a great influence on mechanical operation accuracy, bearing life, friction resistance, temperature rise, vibration and noise. If the choice of the radial bearing clearance is too small, the number of rolling elements bearing the load will increase, the contact stress will be reduced, and the operation will be more stable, but the friction resistance will increase and the temperature rise will also increase. On the contrary, the contact stress increases, the vibration is large, the frictional resistance decreases, and the temperature rise is low. Therefore, it is of great significance to select the most suitable clearance value according to the bearing conditions. When selecting actual bearing clearance, the following main factors must be fully considered:

1. The tightness of the double row deep groove ball bearing and the shaft and housing hole will cause the change of the bearing clearance value. Generally, the clearance value will be reduced after the bearing is installed;

2. During the operation of the double row deep groove ball bearing, due to the difference in heat dissipation conditions between the shaft and the housing, a temperature difference between the inner ring and the outer ring will occur, which will result in a reduction in the clearance value;

3. Due to the different expansion coefficients of shaft and housing materials, the clearance value will decrease or increase.