The basic bearing structure is composed of four parts: inner ring, outer ring, rolling body (steel ball or roller) and cage.

      (1) Inner ring (also known as inner sleeve or inner ring). Usually fixed on the journal, the inner ring rotates with the shaft. There are grooves on the outer surface of the inner ring for steel balls or rollers to roll, which are called inner grooves or inner raceways.

      (2) Outer ring (also called outer jacket or outer ring). It is usually fixed on the bearing housing or the machine's housing and plays the role of supporting rolling elements. The inner surface of the outer ring also has grooves for rolling steel balls or rollers, which are called inner grooves or inner raceways.

      (3) Rolling elements (steel balls or rollers). Each set of bearing is equipped with one or more sets of rolling elements, which are installed between the inner ring and the outer ring, and play the role of each rolling force. Rolling elements are load-bearing parts, and their shape, size, and quantity determine the bearing's ability to withstand the load at high speeds.