Standard Ball Bearing Components

Ball Bearing components: 1. Inner Ring, 2. Outer Ring, 3. Balls, 4. cage
The standard essential components of a ball bearing are defined as follows:

1. Inner Ring:

The Inner Ring is the smaller of the two bearing rings. The inner ring has a groove on its outer diameter to form a pathway for the balls. The surface of the outside diameter path is finished to extremely tight tolerances and is honed to a very smooth. The inner ring is mounted on the shaft and it is the rotating element.

2. Outer Ring:

The Outer Ring is the larger of the two bearing rings. On the outer ring, there is a groove on its inside diameter to form a pathway for the balls. The outer ring surface also has the same high precision finish as the inner ring. The outer ring is usually held stationary.

3. Balls:

Balls of a bearing are the rolling elements that separate the inner ring and outer ring and permit the bearing to rotate with minimal friction. The radius of the ball is made slightly smaller than the grooved ball track on the inner and outer rings. This makes the balls to contact the rings at a single point. Ball dimensions are controlled to very high accuracy. Ball roundness, surface finish and size variations are important attributes. These attributes are controlled to a micro inch level.

4. Cage (Retainer):

The purpose of the cage in a ball bearing is to separate the balls, maintaining constant spacing between the inner and outer rings, accurately guide the balls in the path during rotation and prevent the balls of bearing from falling out.

5. Lubrication:

The lubricant is an integral part of a bearing’s standard components. Lubrication is added to reduce friction losses in bearing between inner and outer rings.

Other Optional Bearing components:

The other additional components shields and seals enhance the performance and life of the ball bearing. These optional components are added to the bearing as per the customer requirement to increase the performance of the ball bearing.


The shield is a stamped, profiled sheet metal disc. The shield is pressed into a very small groove on the inside edge diameter of the outer ring. A small space or gap remains open between the outside diameter of the inner ring and shield. Because the shield does not contact the inner ring of the bearing, there is no added friction between the shield and bearing. This results in a bearing that has very low torque. The purpose of shields is to keep larger particles of contamination from entering the bearing.


The seal is also inserted into the very small groove on the inside, edge diameter of the outer ring. The inner edge of the seal is moulded into a specifically designed lip configuration.
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Vinodh Reddy is a Mechanical Engineer and Editor-in-chief of ME Mechanical. He holds a Bachelor of Engineering (Honours) degree in Mechanical Engineering. He also blogs at EduGeneral. He is interested in the farming field.

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