1. Ball bearings
2. Roller bearings
Ball and roller bearings consist of an inside race which is mount on shaft or journal and an outer race which is carry through housing or casing. In among inner and outer race, there are balls or rollers. A number of balls or rollers are use and these are held at accurate distances through retainers so that they do not touch each other. The retainer are thin strips and are generally in two parts which are assemble after balls have been suitably spaced. Ball bearings are use for light loads and roller bearings are use for heavier loads. Rolling contact bearings, depending upon load to be carried, are classify as:
(a) Radial bearings
(b) Thrust bearings.
When a ball bearing supports just a radial load (WR), plane of revolution of ball is usual to the centre line of bearing, The action of thrust load (WA) is to shift plane of revolution of balls. The radial and thrust loads equally can be carried at the same time.