Standard Ball Bearing Components

Standard Bearing Components

Bearings have a lot in common with cars. A car’s basic design begins with a number of essential components for normal operation and can include additional components which may enhance performance. The same is true for bearings. The essential components of a ball bearing are defined as follows.

The Inner Ring (1)

This is the smaller of the two bearing rings and gets its name from the position it holds. It has a groove on its outside diameter to form a path for the balls. The surface of this path is precision finished to extremely tight tolerances and is honed to a very smooth, mirror-like surface finish. The inner ring is mounted on the shaft and is usually the rotating element.

The Outer Ring (2)

This is the larger of the two rings and, like its counterpart the inner ring, its name is derived from the position it holds. Conversely, there is a groove on its inside diameter to form a pathway for the balls. This surface also has the same high precision finish of the inner ring. The outer ring is normally placed into a housing and is usually held stationery.

The Balls (3)

These are the rolling elements that separate the inner and outer ring and permit the bearing to rotate with minimal friction. The ball radius is slightly smaller than the grooved ball track on the inner and outer rings. This allows the balls to contact the rings at a single point, appropriately called point contact. Ball dimensions are controlled to very tight tolerances. Ball roundness, size variations, and surface finish are very important attributes and are controlled to a micro inch level (1 micro inch = 1/1,000,000th, or one-millionth of an inch).

The Cage (Retainer) (4)

The main purpose of the cage is to separate the balls, maintaining an even and consistent spacing, to accurately guide the balls in the paths, or raceways, during rotation, and to prevent the balls from falling out.

Lubrication

The lubricant is an integral part of a bearing’s standard components. However, the complexity of the subject merits more detailed examination and will be addressed in other training modules.