1. Definition of bearing friction torque:

?The sum of the moments that hinder the movement of a bearing during rotation.

2. Types of bearing friction torque

(1) Static torque: (starting torque)

The friction resistance moment that the two rings of the bearing need to overcome from the static state to the moment when they start to rotate relatively.

(2) Dynamic torque:

The frictional resistance torque required to overcome the relative rotation of the two rings of a bearing. During measurement, the maximum torque, average torque, and torque difference can be extracted as parameters for evaluating the dynamic friction performance of the bearing.

(3) Quasi-static torque:

Although theoretically divided into static and dynamic torques, Japanese scholars have proposed a method based on the theory of similar causes of static and dynamic torques, which uses measurements of dynamic torque at very low rotational speeds to approximate the static torque. This torque is called quasi-static torque.