Angular contact ball bearing rotates at low speed, the shaft bearing friction torque increases with the speed of the bearing, this is because between the ball and raceway elastohydrodynamic lubrication film has not yet been established, bearing basic in the dry lubrication state;

When the bearing rotating speed reaches a certain value, between the ball and raceway lubrication has been formed, bearing friction torque

Decreases with the increasing of the bearing rotating speed, when the bearing rotating speed continues to increase, bearing oil film thickness increases gradually, friction torque caused by the oil film

Also along with the increase, resulting in bearing friction torque as the bearing speed continues to increase.

Bearing lubrication has entered the fluid lubrication state, and smaller outside groove curvature and a half instead of steel ball and the raceway diameter coefficient between oil film formation, thereby

Lower the bearing friction torque;As the speed of the bearing outer ring further rise, appeared bearing friction torque as the coefficient of groove curvature radius.

The trend of increase and decrease.So the coefficient of bearing outside groove curvature radius should be according to the specific conditions for selection.