MECHANICAL COUPLING

Submitted By : GAYATRI S. SOPAL

BEARINGS A coupling is a device used to connect two shafts

together at their ends for the purpose of transmitting power.

Couplings do not normally allow disconnection of shafts during operation

However there are torque limiting couplings which can slip or disconnect when some torque limit is

exceeded.

OVERALL STRUCTURE The inner ring rotates and the outer ring is stationary.

HISTORY The invention of the rolling bearing, in the form of

wooden rollers supporting, or bearing. The captured, or caged, ball bearing was

originally described by Galileo in the 17th century.[

Earliest recovered example is wooden ball bearing supporting a rotating table from the remains of the Roman Nemi Ships.

Leonardo da Vinci incorporated drawings of ball bearings in his design for a helicopter around the year 1500. This is the first recorded use of bearings in an aerospace design.

The first roller bearing was invented in the 1740s by John Harrison for his H3 marine timekeeper.

TYPES of BEARINGS

Plain Bearings

Roller Element Bearing

Jewel Bearing

Fluid Bearings

Magnetic Bearings

Flexure Bearings

Plain Bearings› Simplest type of bearing.› Also known by the specific styles: bushing,

journal bearing, sleeve bearing, rifle bearing.

› Have good Stiffness, low wear.› These Bearings posses relatively high

friction.› Require more maintenance

and lubrication.

Roller Element Bearings Motion is supported by ball or roller bearings. These are used to minimize rubbing. Have good Stiffness. These require cooling while moving at high

speed. Friction is minimizes in these bearings. Require regular maintenance

and lubrication.

Jewel Bearings Motion is supported by rolling the axle

slightly off centre. Have low Friction. Low stiffness due to flexing. Have low speed. Need regular maintenance

and lubrication.

Fluid Bearings Motion is supported by a gas or liquid. These bearings posses low friction. Can be operated at speed of 30 meters/second. Have very long life. Require very low maintenance

and lubrication.

Magnetic Bearings Motion is supported by magnetic field. These bearings posses very low friction than

other all bearings. Have very low stiffness. Can be operated at

Unlimited speed. Have indefinite life. Require no maintenance

and lubrication.

Flexure Bearings Motion is supported by a load element that

bends. Posses very low friction. Have very low stiffness. Operated at very high speed. Life depends on use of material

and strain. Require no maintenance

and lubrication.

Industrial Applications Plain Bearings:-

1) In locomotive of 1960’s motors.2) In Shaft.3) In mining and construction.

Roller element Bearings:-1) Wheels of Bicycle, Automobile.2) Pulley of Cranes.3) Steering wheel of vehicles.

Jewel Bearings:-1) In Incabloc shock protection system ofMechanical watches.2) Galvanometers, Compasses.3) Turbine flow meters.

Fluid Bearings:-1) On drill spindle of printed circuit boards.2) In bicep curl machine and treadmill.3) In leg press and shoulder press.

Magnetic Bearings:-1) In Maglev Trains.2) flywheel energy storage.3) in high-precision instruments.

Flexure Bearings:-1) Electric Motors.2) For machines used in precision3) On the lid of Tic Tac Box

Factors Affecting on Bearings

Friction:-

Load:-

Speed:-

Play:-

Service Life Plain Bearings:-

Depends on application. Rolling element and Flexure bearing :-

life depends on load, handling, temperature, maintenance,

lubrication. Jewel Bearings:-

Have more life. Fluid and magnetic bearings:-

practically indefinite service lives.

Maintenance and Lubrication

To prevent premature failure. Pressure lubrication is required for high speed

machines. For Reliable operation. To reduce friction and prevent wear. To carry away heat. To protect bearing surfaces from corrosion. For optimal service life.