What is a Bearing:
Bearing is a machine element, which supports another moving machine element permitting the
relative motion between the Contact surfaces with minimal friction.
A great variety of rolling bearing types and designs are known, the manifolds of the bearings is
justified by their various purpose of application.
Technical Information About Bearings: Every form of antifriction Bearing consists of four basic
parts:-
An Inner Ring
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.
An Outer Ring
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.
Rolling Elements
These are the rolling elements that separate the inner and outer ring and permit the bearing to
rotate with minimal friction. . Rolling elements can be either Balls, Cylindrical Rollers, Spherical
Rollers, Tapered Rollers and Oil in case of Journal type of Bearings.
A Cage
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. Cage may be of Steel, Brass, Bronze, or Phenolic composition,
depending upon the type and application of the bearings.
Bearings are designed in such a way that they offer following advantages:-
Low Friction--Particularly low starting friction.
The ability to support both radial and thrust load and high speeds of rotation.
Accurate performance under changing load and speed.
High Load Carrying capacity

Operating ability under extreme conditions of speed and performance.
Practically no wear in running.
Simple methods of Lubrication.
Inherently Precision Mechanisms.
The above advantages clearly justify the ubiquitous presence of Bearings in our life.