Abstract :
The theory
behind anti-lock brakes is simple. A skidding wheel (where the tire contact
patch is sliding relative to the road) has less traction than a non- skidding
wheel. If the vehicle have been stuck on ice and if the wheels are spinning
then the vehicle have no traction. This is because the contact patch is sliding
relative to the ice. By keeping the wheels from skidding while you slow down,
anti-lock brakes benefit you in two ways: You'll stop faster, and you'll be
able to steer while you stop. Good drivers have always pumped the brake pedal
during panic stops to avoid wheel lock up and the loss of steering control. ABS
simply gets the pumping job done much faster and in much precise manner than
the fastest human foot.
A simple braking system consists of a master
cylinder, and four wheel cylinders. Every wheel cylinder contains two pistons
which move out words when the hydraulic fluid flows from the master cylinder to
the wheel cylinders through the suitable pipes or lines. Springs are used to hold the brake shoes on
all four wheels. When the brake pedal is pressed the piston in the master
cylinder forces the liquid out of the cylinder. This liquid presses the two
pistons in the wheel cylinders outwards. These two pistons push the brake shoes
out words. The brake shoes in turn press against the brake drums;; this stops
the brake drum which will be rotating. When the brake pedal is released the
master cylinder is pushed backwords.This is done by a spring fitted in the
master cylinder. The springs of the brake shoe brings the shoes closer. The
liquid in the wheel cylinder is pushed outwards through the pipes. It returns
through the pipes to the master cylinder. This is how the hydraulic system of
the four wheels operates
Master
cylinder
It consists
of a reservoir feedhole, bypass port, primarypiston, secondary piston .The
liquid in the reservoir flows through bypass port to the master cylinder. When
the pedal is pressed the primary piston moves to the left .when it crosses the
bypass port the liquid is forced along the pipe lines to the wheel cylinders.
When the pedal is released the primary piston is moved back wards .it is the
spring, which pushes the piston back wards. At the same time a partial vacuum
is developed in the space previously occupied by the spring.
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