braking system for commercial vehicles

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BRAKE SYS
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BRAKE SYS
 The brakes of a veh have to absorb all the energy given to
the veh by the engine and due to the momentum of the veh
 This energy must then be wasted or dissipated
 In most veh brakes, the energy is absorbed by friction,
converted into heat and the heat dissipated by the stream
of air passing under and around the veh
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BRAKE SYS
 The front brakes play a greater part in stopping the car than
the rear ones, because braking throws the car weight
forward on to the front wheels.
 Many cars therefore have disc brakes, which are generally
more efficient, at the front and drum brakes at the rear
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HYD BRAKE SYS

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HYD BRAKES
 Hyd brakes are applied by the driver through an actuating
sys using hyd principles to multiply the brake pedal force
 In a brake actuating sys, the enclosed vessel is a master cyl
and a wh cyl with connecting lines and hoses
 Any pressure applied to the master cyl is transmitted
undiminished to each wh cyl
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HYD BRAKES
 As the brake pedal is depressed, the rod pushes the piston
of the master cyl, thus applying pressure to the brake fluid
 Moving through pipes and hoses to the whl cyl, the fluid
forces apart the cyl pistons, and the later press the shoes
against the brake drums
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HYD BRAKES SYS
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DISK BRAKES
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DISK BRAKES
 A disc brake has a disc that turns with the wh
 The disc is connected by a caliper, in which there are small
hyd pistons worked by pressure from the master cyl
 The pistons press on friction pads that clamp against the
disc from each side to slow or stop it
 The pads are shaped to cover a broad sector of the disc
 There may be more than a single pair of pistons, esp in dual-
circuit brakes
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DISK BRAKES
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DRUM BRAKES
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DRUM BRAKES
 A drum brake has a hollow drum that turns with the wh
 Its open back is covered by a stationary back plate on which
there are two curved shoes carrying friction linings
 The shoes are forced outwards by hyd pressure moving
pistons in the brake's wh cyl
 The linings is pressed against the inside of the drum to slow
or stop it
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DRUM BRAKES
 Each brake shoe has a pivot at one end and a piston at the
other
 A leading shoe has the piston at the leading edge relative to
the dir in which the drum turns
 It is simpler but less powerful than the two-leading-shoe
system, and is usually restd to rear brakes
 Shoe travel is kept as short as possible by an adjuster
 Brakes have automatic adjustment by means of a ratchet
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DRUM BRAKES
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THANK YOU
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