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Brakes
A brake is a device by means of which artificial frictional resistance is
applied to a moving machine member, in order to retard or stop the motion
of a machine
...
The energy absorbed by the brakes is dissipated in the form of heat
...
The mechanical brakes, according to the direction of acting force,
may be divided into the following two groups :
(a) Radial brakes
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The radial brakes may be subdivided into external brakes and internal brakes
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(c) Axial brakes
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The axial brakes may be disc brakes
and cone brakes
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(MECHANICAL BRAKES)
BLOCK BRAKE (SINGLE BLOCK OR SHOE BRAKES)
A single block is consists of a block which is pressed against the rim
of revolving brake wheel drum
...
The prony brake is
example of block brake
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These shoes apply force to both the sides of wheel and reduces the Unbalanced force
on the shaft
...
When a force is applied to the bell crank level , the spring is Compressed and the
brake is released
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The bicycle brake is example of double block brake
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When an
upward force is applied to the lever end, the lever turns about
the fulcrum pin and tightens the band on the drum and hence the
brakes are applied
...
This type of brake is used in civil construction equipment
and also in automobiles as hand brake
...
Applications; Merry go round,
Giant wheel
(MECHANICAL BRAKES)
INTERNAL EXPANDING SHOE BRAKE
An internal expanding shoe brake consists of two
shoes
...
Each shoe is pivoted at one end about a fixed
fulcrum and other end rests against cam
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The friction between the shoes and the drum
produces the braking torque
...
(MECHANICAL BRAKES)
INTERNAL EXPANDING SHOE BRAKE
https://www
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com/watch?v=MAuVDB-G-HQ
(MECHANICAL BRAKES)
DISC BRAKES
Disc brakes are different from drum brakes in that the
drum is replaced by a circular metal disc and the brake
shoe are replaced by a caliper which supports a pair of
friction pads , one on each side of the disc
...
DISC BRAKE
HYDRAULIC BRAKING SYSTEM
Vacuum Braking System
Construction and Working
brakes
The design or capacity of a brake depends upon the following factors :
1
...
The coefficient of friction between the braking surfaces,
3
...
The projected area of the friction surfaces
...
The ability of the brake to dissipate heat equivalent to the energy being
absorbed
...
brakes
Heat to be Dissipated during Braking
The energy absorbed by the brake and transformed into heat must be
dissipated to the surrounding air in order to avoid excessive temperature rise
of the brake lining
...
Materials for Brake Lining
The material used for the brake lining should have the following characteristics :
1
...
In other
words, the coefficient of friction should remain constant over the entire surface
with change in temperature
...
It should have low wear rate
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It should have high heat resistance
...
It should have high heat dissipation capacity
...
It should have low coefficient of thermal expansion
...
It should have adequate mechanical strength
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It should not be affected by moisture and oil
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One end of the lever is
attached to a fix point also called as pivot point & force is applied to the other end
...
• Single Block or Shoe Brake
This type of a brake is commonly used on railway trains and tram cars
...
The blocks maybe wooden or any other
friction lined material
...
These
types of brakes were widely used in trains
...
When the frictional force helps to apply the brake, then the brake is said to be
self-energizing brake
Internally expanding brakes
when we rotate the cam the brake
shoes get expanded in radially
outward direction thus applying
pressure on the inner surface of
drum
...
When
we release the cam, the spring
having the tendency to contract,
pulls the shoes towards itself
allowing the drum to rotate again