INTRODUCTIONA Bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement.

When there is a relative motion between two machine parts, one of which supports the others.The supporting member is called Bearing.

TERMINOLOGY• Inner race

• Outer race

• Inner and outer diameters

• Width

Geometry of Rolling Contact Bearings

SELECTION OF BEARING TYPE

Each bearing type displays characteristic properties, based on its design which makes it more, or less appropriate for a given application

The most important factors to be considered when selecting a standard bearing type and thus a facilitate an appropriate choice :

Available space

Loads

Misalignment

Precision

Speed

Quiet running

Stiffness

Axial displacement

Mounting and dismounting

Integral seals

LOADSMAGNITUDE OF LOAD :-

The magnitude of the load is one of the factors that usually determines the size of the bearing to be used. Generally, roller bearing are available to support heavier loads than similar size ball bearing and bearings having a full compliment of rolling elements can accommodate heavier loads than the corresponding caged bearing.

DIRECTION OF LOAD

Radial load :- The load which comes perpendicular on the shaft called redial load.

Cylindrical roller bearing, needle roller bearing, and toroidal roller bearing can only support pure Radial loads.

DIRECTION OF LOADAxial load :-

The load which comes axis on the shaft called Axial load.

Thrust ball bearing and four point contact ball bearing are suitable for light or moderate loads that are purely axial.

DIRECTION OF LOADCombined load :- A combined load comprises a redial and an axial load acting simultaneously

For combined loads, single and double row angular contact ball bearing, and single row taper roller bearing are most commonly used, although deep groove ball bearing and spherical roller bearing

are suitable.

SPEEDThe permissible operating temperature limits the speed at which rolling bearings can be operated. Bearing types with low friction and correspondingly low heat generation inside the bearing are therefore the most suitable for high - speed operation.

BALL BEARING

A Ball bearing is a common type of rolling – element – bearing.

-Point contact; support radial and axial loads.

ANGULAR CONTACT BALL BEARING

Designed for axial loading; used in pairs

These bearing are used where the thrust load is equal to or greater than radial load.

THRUST BALL BEARING– Designed for pure axial loading

This type comprises a row of balls running between two flat groove washers with balls track designed to absorbed thrust load in one direction this does not with stand any radial loads, also with this

is not suitable for higher speeds.

ROLLER BEARINGRoller bearings are used in rotary applications to replace sliding movement with low friction, rolling motion. The principal types of roller bearings are cylindrical, spherical, and tapered. In general, roller bearings offer higher load capacities than ball bearings of the same size

CYLINDRICAL ROLLER BEARING

– Supports high radial loads; slower speed ratings

TAPERED ROLLER BEARINGHigh radial and axial load ratings; used in pairs

These bearings carry heavy loads at moderate speed. There should always be mounted in pairs with opposed taper because in each bearing the radial load produced an axial component which needs counter balance

SPHERICAL ROLLER BEARING

– Allows for misalignment

These bearings are suitable for use with independent support housing and wherever there is possibility of a lack of alignment. It can carry medium or heavy redial or combined load.

NEEDLE ROLLER BEARING

Thrust and radial types; typically no inner race

These bearings are used in plans where the speed in low or oscillation takes place as in wrist pin, rocker arm,

universal joint etc.