Band brake

SUBJECT

BASIC MECHANICAL ENGINEERING

Topic

BAND BRAKE

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PRESENTED BY

SHAHID NAZEER FROM DEPARTMENT OF ELECTRICAL ENGINEERING ,UCE&T ,BZU MULTAN, PAKISTAN

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WHAT IS BRAKE?• A device for slowing or stopping a moving

vehicle, typically by applying pressure to the wheels.

• Friction between Drums & Shoes or Pads & Rotors slows the vehicle.

• Friction between TIRES and ROAD stops the car.

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Band Brake

• A band brake is a primary or secondary brake, consisting of a band of friction material that tightens concentrically around a cylindrical piece of equipment to either prevent it from rotating (a static or "holding" brake), or to slow it (a dynamic brake).

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PARTS OF BAND BRAKE

•Band• The band brake is a circular piece of spring

steel that is rectangular in cross section. Its inside circumference is lined with a friction material. The band brake has bosses on each end so that it can be held and compressed.

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DRUM• The drum fits inside of the band and

attaches to the planetary gear-set element and is to be locked by the band. Its outer surface is machined smoothly to interact with the friction surface of the band brake. By pulling the open ends of the band together, the rotation of the drum stops.

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ANCHOR

• The anchor firmly attaches one end of the brake band to the transmission case. A provision for adjusting the clearance between the band and the drum is usually provided on the anchor.

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Servo• The servo uses hydraulic pressure to

squeeze the band around the drum.• The servo piston is acted on by hydraulic

pressure from the valve body that is fed through an internal passage through the case.

• The servo piston has a seal around it to prevent leakage of hydraulic pressure

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Construction of Band Brake• A band brake is made up of a rope or belt

band which is lined with a frictional material. • This band is wrapped partially around a drum

with its free ends are connected to a lever.

• An external force can be applied to the free end of this lever for braking.

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• Due to the addition of external force there is

friction between the band.

• Due to this frictional force, the band is tightened and a tangential force acts on the drum.

• The tightening of the band creates tension in the

band.

• IT STOP THE WHEEL CONNECTED .

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Working of Band Brake

•When ReleasedWhen the brake band is released, there is no

hydraulic pressure applied to the servo, and the drum is free to rotate within the band.

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When Applied;

Hydraulic pressure is applied to the servo that, in turn, tightens the band around the drum.

The result is that the drum is locked in a stationary position, causing an output change from the planetary gearset.

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CLASSIFICATION OF BAND BRAKE

• BAND BRAKES CAN BE CLASSIFIED AS

• SIMPLE BAND BRAKE:

• DIFFERENTIAL BAND BRAKE:

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Difference between Simple Band Brake and Differential Band Brake

Simple Band Brake• Fulcrum is at one end of

lever.

• Is not self-energizing .

• Is not self-locking .

Differential Band Brake• The fulcrum is between the

two ends of the lever.

• Is always self-energizing .

• It can be Self-locking.

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Effectiveness

• The effectiveness of the brake is described as where is the coefficient of friction between band and drum, and is the angle of wrap.

• With a large , the brake is very effective and requires low input force to achieve high brake force, but is also very sensitive to changes in .

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Efficiency• One of the major benefits of a band brake is

the simplicity of the design.

• a band brake assembly is easily maintained and can work properly for a number of years with no breakdowns.

• If drum is kept clean and free from rust then break would work well.

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Advantages and Disadvantages

Advantages• simple• compact• rugged • generate high force

with a light input force.

Disadvantages• band brakes are

prone to grabbing or chatter and loss of brake force when hot.

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APPLICATION OF BAND BRAKE

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