Roller bearing is a kind of rolling bearings, one of the parts widely used in modern machinery. It relies on the rolling contact between the main components to support the rotating parts. Roller bearings are now mostly standardized. Roller bearings are designed to take a radial load while reducing friction, has the advantages of small starting torque, high rotation accuracy, easy selection and so on. The key difference between a roller bearing and a ball bearing is that they are cylindrical shapes rather than spherical balls.