Abstract: Based on the dynamics and thermodynamic analysis of angular contact ball bearings, the theoretical computational formulae of the friction torque of angular contact ball bearings are obtained with the law of energy conservation. The theoretical analysis and the experimental verification for the effects of the structural parameters, operation condition on frictional torque of the angular contact ball bearings are presented. The results show that a big inner groove curvature radius coefficient is in favor of reducing the friction torque under low rotation speed, when the bearings work at high speed, a small inner groove curvature radius coefficient is better. A large outer groove curvature radius coefficient yields low friction torque in low or high speed operation, and a small one should be chosen for medium speed operation. It is unfavorable to reduce the friction torque of the angular contact ball bearings if the cage guiding clearance is oversize or undersize, and there is a reasonable cage guiding clearance to get the lowest friction torque. The square type cage pocket is better for the reduction of friction torque under low speed condition, and the straight cage pocket has advantages under high rotation speed condition.

Key words: Angular contact ball bearings, Bearing parameters, Dynamics, Friction torque