Ball bearing

A bearing is a device that allows constrained relative motion between two or more parts, typically rotation or linear movement. A ball bearing is a type of bearings which uses balls to maintain the separation between the moving parts of the bearing, in order to reduce rotational friction and support radial and axial loads. Today the ball bearing is used in numerous everyday applications, as compared to other rolling-element bearings the ball bearing is the least expensive, primarily because of the low cost of producing the balls used in the bearing.