Bearings work under rolling friction. Rolling bearing easy to use and maintain, reliable, starting performance, high load capacity at medium speed. Compared with the plain bearing, the larger the radial size of the rolling bearing, the poorer the damping capacity, the lower the life at high speed and the louder the sound. Radial bearings in rolling bearings (mainly radial forces) are usually composed of 4 parts of inner ring, outer ring, rolling element and rolling element cage. The inner ring is tightly sleeved on the journal and rotates together with the shaft. The outer ring is mounted on the bearing seat hole. Raceways are made on the inner periphery of the inner ring and the inner ring of the outer ring. When the relative rotation of the inner and outer rings, the rolling elements that race on the inner and outer rings rolling, they are separated by the cage, to avoid mutual friction. Thrust bearing sub-tight ring and living ring in two parts. Tight circle and sleeve tight, live ring bearing in the bearing. Rings and rolling elements are usually made of high strength, good wear resistance of the rolling bearing steel, the surface hardness after quenching should reach HRC60 ~ 65. Cage made of mild steel stamping, copper alloy cloth can also be used to make bakelite or plastic.