Bearings (Bearing) is an important part of contemporary mechanical equipment. Its main function is to support mechanical rotator, reducing its coefficient of friction during exercise (friction coefficient), and ensure that its rotation accuracy (accuracy).

Friction properties of different movement components, bearing two categories can be divided into roller bearings and plain bearings. Rolling bearings have standardized, serialized, but compared with plain bearings radial dimensions, vibration and noise, the price is high.

Rolling bearings generally consist of outer ring, inner ring, rolling elements and cage consists of four parts, strictly speaking consists of outer ring, inner ring, rolling elements, cage, seal and lubricating oil consists of six large pieces. In short, as long as the outer ring, inner ring, rolling elements can be defined as rolling bearings. Rolling body shapes, rolling bearings are divided into two types of ball bearings and roller bearings.