What are Bearings and Their Types and Functions

This article will understand what the bearings are, their types, and how life can be increased. Each and everything about the bearing will be explained in simple words so that everybody could understand.


What are Bearings?

Bearings are a device that is used to support and guide the rotating or sliding shaft. Generally bearing is designed to have the following functions:

  • to reduce friction
  • In guiding the movie parts for example; wheels, shafts, and pivots
  • and supporting the load

Functions of Bearing

Bearings are generally designed to perform 3 kinds of functions which are given below:

  • Reducing the friction
  • Support the load
  • Guiding the moving parts

we will discuss each of them one by one.

Reducing the friction

the bearing’s main function is to reduce the friction between the sliding parts. Bearings have a common objective which is to reduce friction whether they are used in automobile machines fleet or at any other place.

the bearing’s internal rolling mechanism is designed in such a way that it requires less energy and effort to slide the object over the other.

Supports the load

The shaft is generally trying to push the bearing in the same direction as the load moves. If we choose the wrong bearing then it might not be able to carry the kind of loads and repairing might get failure. The load is dependent on the direction and the weight.

Before understanding this we need to first understand the type of loads acting on the bearing. There are three kinds of loads which are given below:

  • Radial Load
  • Thrust Load
  • Angular Load

Radial Load

The word radial means in the direction of the radius moving in outward of the circumference. Radial load pushes down the from outward of the bearing to the inward of balls cage and then in a race of the bearing. The load acts perpendicular to the center of the axis of the shaft.

Thrust Load

Thrust lord is defined as the pressure exerted by load sliding against the other part. In this case, the pressure is exerted sideways, pushing the shaft either right or left. This pressure is then exerted on the bearings in the same sideways direction. In this case, the line of pressure offline runs parallel to the axis of the shaft.

Angular Load

An angular load is basically the combination of both radial and thrust loads. In this case, the pressure is transmitted diagonally through the corner of the outer is to the balls and then to the cage to the opposite corner of the outer race.

Guiding the moving parts

The bearings help in guiding the moving parts one over the other. If there are no bearings, one part will not roll over the other smoothly and consistently.

Parts of a Bearing

A bearing consists of the following four parts:

  • Outer race
  • Inner race
  • Rolling elements
  • Cage
Parts of a Bearing
Parts of a Bearing

Outer Race

the outer race or the outer ring is the exterior part of the bearing and it protects the internal parts like in a cage rolling elements of the bearing. So it’s should be machined properly.

Inner Race

The inner race is the parts of the bearing that fits directly on the shaft. The inner race is also called the inner ring or cone.

Rolling Elements

Balls or rollers are the rolling elements that provide the cushion to ease the moving friction of the shaft within the housing. These rolling elements keep the inner and outer race separated and enable them to move freely and easily.


A cage or separator is a metal retainer that holds the balls or rollers and keeps the balls or rollers at an equal distance.

Ball Bearing Types

Ball bearings are generally classified into two types which are given below:

  • Ball Bearings
  • Roller Bearings

We will discuss each of them one by one.

1. Ball Bearings

Ball bearings are used in trucks, cars, machines, and in many other applications. They are used in many industrial applications as well.

Ball Bearings
Ball Bearings

a.) Single Row Ball Bearing

Single-row ball bearings are the most used bearings. In these ball bearings, the balls roll in the cut of both the inner and outer races. It is designed for the radial load but can also bear thrust load in either direction.


• Transmission
• Differential
• Steering gear
• Air conditioner clutch

b.) Angular Contact Ball Bearing

The main feature of the angular contact ball bearing is that it has two high thrust supporting shoulders. Out of these two, one is on the inner race and the other is on the opposite side of the outer race. Though this design can support heavy thrust load in one direction, it can also be combined with a moderate radial load sometimes.

c.) Double Row Ball Bearing

Double row ball bearings are the combination of the design principle of both angular contact ball bearing and single row ball bearing.

d.) Ball thrust Ball Bearing

The ball thrust bearings are designed for high thrust applications.

2. Roller bearings

Roller Bearings
Roller Bearings

a.) Tapered Rollers

The tapered rollers bearings are similar to the wide edge of the cone rather than a circle. These bearings can support all kinds of loads i.e. radial load, thrust load, or a combination of these two loads. Tapered roller bearings are used in automobiles, and various farming vehicles, including:
• Transmissions
• Transfer cases
• Front wheels
• Trailer wheels

b.) Cylindrical Rollers

In these bearings, the rollers are kept evenly spaced by a cage which guides their turning movement on the flat surface of the two races. Cylindrical rollers bearings are used in:
• Transmissions
• Differentials
• Rear Axle Shafts

c.) Needle Rollers

Needle roller bearings are similar to roller bearings. The main difference is the roller design capacity. The rollers in Needle Rollers are of thinner diameter as compared to the cylindrical rollers. Needle rollers bearings are used in
• Transmissions
• Alternators
• Steering gears
• Universal joints

For more info, visit skf official website

Also check Centrifugal Pumps, Types, Parts, Working Principle Explained

Also check video on how to read specifications of bearing

How to read a bearing number

Frequently Asked Questions

1. What is the function of the bearings?

Reducing the friction
Support the load
Guiding the moving parts

2. What are the parts of a Bearing?

Outer race
Inner race
Rolling elements

If you have any doubts, please comment down below.