BEARINGBEARING

Format of Format of presentationpresentation

What is bearing?What is bearing? History.History. Bearing loads.Bearing loads. Principles of operations.Principles of operations. LubricantsLubricants Interesting uses.Interesting uses. Rolling contact bearings.Rolling contact bearings. Components of rolling contact bearing.Components of rolling contact bearing. Types.Types. Bearing materials.Bearing materials. Bearing selection.Bearing selection. Catalogue information.Catalogue information. Design of rolling element bearing.Design of rolling element bearing. Mounting of bearings.Mounting of bearings. Advantages over sliding friction.Advantages over sliding friction.

What is Bearing?What is Bearing? It is a device where loads are It is a device where loads are

transmitted through contacting transmitted through contacting surfacessurfaces

It is desired to minimize friction and It is desired to minimize friction and wearwear

Lubricant – material between surfaces Lubricant – material between surfaces that reduces friction and wearthat reduces friction and wear

Any moving part of the machine has to Any moving part of the machine has to be supported by a relatively stationary be supported by a relatively stationary part which can be called bearing.part which can be called bearing.

HISTORYHISTORY Any early type of liner Any early type of liner

bearing was an bearing was an arrangement of tree arrangement of tree trunks laid down under trunks laid down under loads. loads.

The first practical caged The first practical caged roller bearing was roller bearing was invented by JOHN invented by JOHN HARRISON in 1760.HARRISON in 1760.

Bearing Loads.Bearing Loads. Bearing typically have Bearing typically have

to deal with following to deal with following types of load.types of load.

Radial loads.Radial loads. Thrust loads.Thrust loads. Combination of both.Combination of both.

Radial loads.Radial loads.

These loads act towards These loads act towards the centre of bearing the centre of bearing along a radius.along a radius.

These loads are These loads are created by spur gears, created by spur gears, V belt drives & Chain V belt drives & Chain drivesdrives

Thrust loads.Thrust loads. These loads are These loads are

those that act those that act parallel to the axis of parallel to the axis of shaft.shaft.

Bearing supporting Bearing supporting shafts are subjected shafts are subjected to thrust loads due to thrust loads due to weight of shaft & to weight of shaft & elements on shaft & elements on shaft & also due to axial also due to axial operating forces.operating forces.

Combination of both.Combination of both.

The bearing like shown The bearing like shown is like the one in the is like the one in the hub of your car wheel. hub of your car wheel. This bearing has to This bearing has to support both a radial support both a radial load & a thrust load.load & a thrust load.

Principles of operation.Principles of operation.

Sliding bearings Sliding bearings (bushing, journal, (bushing, journal, sleeve)sleeve)

Rolling element Rolling element bearingsbearings

Fluid bearings.Fluid bearings. Magnetic bearings.Magnetic bearings.

Lubricants Lubricants

Oil – heavy petroleum distillate, animal oils, Oil – heavy petroleum distillate, animal oils, vegetable oils plus additives vegetable oils plus additives

Grease – Used as a barrier to dirt and debris. Grease – Used as a barrier to dirt and debris. No circulation, thus no cooling or cleaning.No circulation, thus no cooling or cleaning.

Solid – graphite, teflonSolid – graphite, teflon

Bearings classificationBearings classification

Types of bearings

Sliding Rolling

Journal thrust

Other typesOther types

Some interesting uses.Some interesting uses.

Magnetic bearingsMagnetic bearings

high speed devices high speed devices like like advanced flywheel advanced flywheel

energy storages energy storages system system use magnet use magnet bearings.bearings.

Giant roller bearingsGiant roller bearings

This is use when This is use when large large heavy objects heavy objects needs to needs to be movedbe moved

Giant ball bearings.Giant ball bearings.

This technology is This technology is used in advanced used in advanced building constructions building constructions like San Francisco like San Francisco international airport international airport to withstand earth to withstand earth quakes.quakes.

TechnologyTechnology

The 267 columns that support The 267 columns that support the weight of the the weight of the airport each each ride on a 5-foot-diameter (1.5-ride on a 5-foot-diameter (1.5-meter) steel ball bearing. The meter) steel ball bearing. The ball rests in a concave base ball rests in a concave base that is connected to the that is connected to the ground. In the event of an ground. In the event of an earthquake, the ground can earthquake, the ground can move 20 inches (51 cm) in any move 20 inches (51 cm) in any direction. The columns that rest direction. The columns that rest on the balls move somewhat on the balls move somewhat less than this as they roll less than this as they roll around in their bases, which around in their bases, which helps isolate the building from helps isolate the building from the motion of the ground. When the motion of the ground. When the earthquake is over, the earthquake is over, gravity pulls the columns back to the pulls the columns back to the center of their bases. center of their bases.

Rolling element bearingsRolling element bearings It is bearing that It is bearing that

carries a load by carries a load by placing round element placing round element between the two between the two pieces. The relative pieces. The relative motion of the pieces motion of the pieces causes element to roll causes element to roll with little sliding.with little sliding.

Rolling element can be Rolling element can be spherical ball or some spherical ball or some kind of roller. kind of roller.

Rolling Elements BearingsRolling Elements Bearings Substitute rolling friction for sliding frictionSubstitute rolling friction for sliding frictionCompose of four elements:Compose of four elements: Outer ring, which contains outer racewayOuter ring, which contains outer raceway Rolling elements, balls, rollers, tapered rollers, Rolling elements, balls, rollers, tapered rollers,

needlesneedles Inner ring, which contains inner racewayInner ring, which contains inner raceway Separator/retainerSeparator/retainer

Categories:Categories:Radial, Thrust and AngularRadial, Thrust and Angular

Components of rolling element Components of rolling element bearingbearing

The components The components includesincludes

inner race.inner race. rolling element.rolling element. outer race.outer race. separator, retainer, or separator, retainer, or

cage cage shoulders.shoulders. snap ring groovesnap ring groove seal or shield notch.seal or shield notch. seal or shield groove. seal or shield groove.

Types of rolling element Types of rolling element bearingbearing

They are classified asThey are classified as ball bearings.ball bearings. roller bearings.roller bearings. ball thrust bearings.ball thrust bearings. roller thrust bearingsroller thrust bearings taper roller thrusttaper roller thrust

bearings.bearings.

Ball bearings.Ball bearings.

These can handle both These can handle both radial & thrust loads. radial & thrust loads. these can be divided asthese can be divided as

single row deep groove single row deep groove ball bearing.ball bearing.

double row deep double row deep groove ball bearing.groove ball bearing.

angular contact ball angular contact ball bearing.bearing.

Duplex ball bearings.Duplex ball bearings. Four point ball bearing.Four point ball bearing.

Single row deep groove ball Single row deep groove ball bearingsbearings

They are highly suitable for applications They are highly suitable for applications where high speed & low power loss are where high speed & low power loss are requiredrequired

Angular Contact Ball Angular Contact Ball BearingsBearings

Single row angular contact Single row angular contact ball bearings.ball bearings.

They can handle radial & They can handle radial & also axial loadsalso axial loads

Double row angular contact Double row angular contact ballball bearings.bearings.

They can handle axial load They can handle axial load loads in either direction. loads in either direction.

Duplex bearingsDuplex bearings

A combination of two radial A combination of two radial bearings is called duplex bearings is called duplex bearings. Usually bearings. Usually combination is ball bearing combination is ball bearing or tapered bearings.or tapered bearings.

Four point ball bearings.Four point ball bearings.

The inner ring & outer rings The inner ring & outer rings are separable .They can take are separable .They can take axial loads in either direction.axial loads in either direction.

Roller bearingsRoller bearings These can handle These can handle

greater radial loads.greater radial loads.

They are classified as They are classified as Cylindrical roller Cylindrical roller

bearings.bearings. Spherical roller Spherical roller

bearings.bearings. Tapered roller bearings.Tapered roller bearings. Needle roller bearings.Needle roller bearings.

Cylindrical roller bearingsCylindrical roller bearings

They can handle They can handle high radial load high radial load capacity & are capacity & are suitable for high suitable for high speeds.speeds.

Spherical roller Spherical roller bearingsbearings

Tapered roller Tapered roller bearingsbearings

Needle roller bearingsNeedle roller bearings

The applications is The applications is in pumps ,universal in pumps ,universal joints, precision joints, precision instruments & instruments & household household appliances.appliances.

Thrust ball bearings.Thrust ball bearings.

These are used for These are used for low speed low speed application & application & cannot handle cannot handle much radial load.much radial load.

Single direction thrust ball bearingsSingle direction thrust ball bearings

Double direction thrust ball bearingsDouble direction thrust ball bearings

Roller thrust bearing.Roller thrust bearing.

They can support They can support large thrust loads.large thrust loads.

Applications are Applications are in gear sets like car in gear sets like car transmission transmission between gears.between gears.

Between housing Between housing & rotating shafts.& rotating shafts.

Spherical roller Spherical roller thrust bearingsthrust bearings

Lubrication – basic typesLubrication – basic types

No contact Some contact Significant wear

No wear Mild wear

Hydrodynamic lubrication : Complete surface separation by a highly pressurized gas or fluid

Variation of Co-efft. of Variation of Co-efft. of frictionfriction

-Viscosity: the higher viscosity the lower speed needed to float the journal at a given load (Also as increases, f also increases

N – rev/sec: the higher n the lower is needed to float the journal at a given load (also as n increases, f also increases)

P=W/DL – Bearing unit load (load/projected area) the smaller P the lower and n needed to float the journal

tyres

Hydrodynamic lubricationHydrodynamic lubrication

Lubricating oil in the boundary layer of the rotating shaft flows into converging zone between the shaft and bearing,moving the shaft slightly to the left of center.

The surfaces of the shaft and the bearing are completely separated by the lubricant. The shaft rotation also causes the lubricant layer to be continuously replenished.

Grease or oil – when and Grease or oil – when and wherewhere

Grease Oil

1. Temperature is not over 200oF Temperatures are high

2. Speed is low Speed is high

3. Unusual protection is required from Oil tight seals are readily entrance of foreign matter employed

4. Simple bearing enclosures are desired Bearing type is not suitable for grease

lubrication

5. Operation for longer periods without The bearing is lubricated from attention is desired. a central supply which is also used for other machine parts

Bearing selectionBearing selection

It involves,It involves, Load carrying capacity.Load carrying capacity. Geometry of bearingGeometry of bearing grade of precision (usually grade of precision (usually

ABEC 1).ABEC 1). lubricant.lubricant. Closure (open, shielded Closure (open, shielded

or sealed).or sealed). Maximum speed.Maximum speed.

Design life.Design life.

Catalogue information Catalogue information for rolling contact for rolling contact

bearingsbearingsBearing manufactures catalogues provides Bearing manufactures catalogues provides

information such asinformation such as bearing numbers.bearing numbers. dimensional information.dimensional information. rated load capacities.rated load capacities. bearing weight. bearing weight. Details regarding mounting & Details regarding mounting &

lubrication. lubrication.

Bearing numberBearing number

Bearing numbers are alphanumeric Bearing numbers are alphanumeric combinations that indicate the bearing type, combinations that indicate the bearing type, boundary dimensions, dimensional and boundary dimensions, dimensional and running accuracies, internal clearance, and running accuracies, internal clearance, and other related specifications. They consist of other related specifications. They consist of basic numbers and supplementary symbols. basic numbers and supplementary symbols.

Formulation of Formulation of bearing numbersbearing numbers