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What is a Radial Bearing?

Paul Scott
Paul Scott

Radial bearing is a term used to describe a bearing that support an axial rotating load by distributing the load forces along the radius. In simpler terms, a radial bearing supports and keeps a revolving shaft turning smoothly by spreading the load around its inner surface on a set of free running balls or rollers. These rollers are typically made of hardened steel or ceramic materials and have a very low friction coefficient. There are a number of different radial bearing designs, including split race and caged, each particularly suited to a specific application. Radial bearings may also include design features which allow them to be self aligning and to better absorb off-center loads.

Radial bearings consist of two races which form inner and outer running surfaces for a set of ball or roller elements. The inner race of the bearing fits tightly on the revolving shaft and the outer race is held static in a purpose designed pocket in part of the machine's structure. The two races are grooved or shaped on their inner surfaces to accept and retain the balls or rollers. When the machine runs, the inner race rotates with the shaft while the outer race remains stationary. The balls or rollers between the races support the shaft axially with very little friction while distributing the loads it carries around the radius of the bearing.


Various materials are used to construct radial bearings. Conventional bearings typically feature races, balls, and rollers made of hardened steel to withstand the loads imposed on the bearing. Ceramic hybrid bearings have steel races but utilize balls made of light weight ceramic material. A ceramic radial bearing has less inherent friction between the races and balls and requires less energy to maintain rotational speed. As a result, these bearings can withstand operational speeds between twenty and forty percent higher than conventional bearings.

Radial bearing design include variations such as the split race bearing that allows balls to be added or removed according to the application requirements. Caged bearings have their balls or rollers held in position in a brass or steel cage. This allows the bearing to operate with fewer balls with a resultant reduction in friction. Deep groove radial bearings feature inner race profiles close to the dimensions of the balls. These bearings can carry higher loads but cannot support misaligned loads as well as shallow groove varieties.

Self aligning radial bearings typically feature double rows of balls or rollers shaped like a wine barrel. This type of bearing has oval inner and outer race profiles which allow for a certain amount of axial displacement. The shape of the rolling supports and races makes it possible for the inner race to tilt off-axis slightly without displacing the rollers in the outer race. If a misaligned load is applied to the self aligning radial bearing, it will allow for rotation without damage to its balls, rollers, or races.

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