Today we will discuss about hydraulic brake system. It is one of the most useful braking system. Most of the cars today use hydraulically operated foot brakes
on all the four wheels with an additional hand brake mechanically operated on
the rear wheels. This type of brake is more reliable and easy to handle. Today
almost all passenger cars use this type of braking system. This type of braking
system is used because -
1. The hydraulic fluid exerts equal pressure everywhere in its
circuit. For this reason equal braking effort is obtained at all the four
wheels.
2. This is simple in construction, due to the absence of brake
rods. It used pipelines to transfer fluid which can be bent and shaped
according to the underside of the body structure.
3. Due to absence of joints compared to mechanical brakes, rate
of wear is also less.
ALSO READ : TYPES OF BRAKES
Hydraulic Brake System:
Layout of hydraulic brake system:
The main component of hydraulic braking system is master
cylinder, which contains reservoir for the brake fluid. Master cylinder is
operated by the brake pedal and is further connected to the wheel cylinders in
each wheel through steel pipe lines. This system is so designed that even when
the brakes are in the released position, a small pressure of 50kPa is maintained
in the pipe line to ensure that the cups of the wheel cylinder are kept
expanded.
As we discussed in my last post that all braking system work
on the friction principle so it also used drum or disk brake to slow down the
vehicle but the force is exerted by the hydraulic oil so named as the hydraulic
braking. The master cylinder is basically a piston cylinder device contain
fluid. When the pedal is pressed, push rod moves the piston inside the cylinder
which builds up a pressure. Due to this pressure hydraulic fluid is forced into
the pipes under pressure. This fluid enters the wheels where a small piston
cylinder arrangement known as caliper. This high pressure oil push this piston
pads towards drum or disk thereby applying the brakes.
The main component of this braking system is the master
cylinder. The working and design of master cylinder is as follow-
Design and Working of Master Cylinder:
This can be named as heart of the hydraulic braking system. There
are two chambers. The upper one is known as fluid reservoir and the lower one
is known as compression chamber in which the piston operates. The fluid in the reservoir
compensates for any change in the fluid volume in the pipelines due to
temperature variation and due to leakage. There are rubber seal on both ends of
the piston. A rubber boot covers the push rod end of the master cylinder to
prevent the dirt from entering inside.
At the brake lines side of the compression chamber, there is
a fluid check valve with a rubber cup inside. It serves to retain the residual
pressure in the brake lines even when the brakes are released.
Two holes connect the reservoir to the compression chamber. The
smaller one is known as bypass and second hole is known as intake port. The push
rod is operated by the foot brake pedal. As the pedal is pressed, push rod
moves the piston left against the force of the spring, till it covers the
by-pass port. Further movement of the push rod causes building up of pressure
in the compression chamber. Finally, when sufficient pressure has built up, the
inner rubber cup of the fluid check valve deflected, forcing the fluid under pressure
in the lines. This fluid enters the wheel applying brakes.
Today we have discussed about hydraulic brake system. If you have any query ask by commenting.
Today we have discussed about hydraulic brake system. If you have any query ask by commenting.