give the principle and explain the working of hydraulic brakes
Answers
Hydraulic Brakes
Hydraulic brakes work on the principle of Pascal’s law.
According to this law whenever pressure is applied on a fluid it travels uniformly in all the directions.
Therefore when we apply force on a small piston, pressure gets created which is transmitted through the fluid to a larger piston. As a result of this larger force,uniformbrakingis applied on all four wheels.
As braking force is generateddue to hydraulic pressure,theyare known as hydraulic brakes.
Liquids are used instead of gas as liquids are incompressible.
Construction
The fluid in the hydraulic brake is known as brake fluid.
It consists of a master cylinder, four wheel cylinders and pipes carrying brake fluid from master cylinder to wheel cylinders.
Master cylinder consists of a piston which is connected to pedal through connecting rod.
The wheel cylinders consist of two pistons between which fluid is filled.
Each wheel brake consists of a cylinder brake drum. This drum is mounted on the inner side of wheel. The drum revolves with the wheel.
Two brake shoes whichare mounted inside the drum remain stationary.
Working
When we press the brake pedal, piston in the master cylinder forces the brake fluid through a linkage.
As a result pressure increases and gets transmitted to all the pipes and to all the wheel cylinders according to Pascal’s law.
Because of this pressure,both the pistons move outand transmit the braking force on all the wheels.
Advantages:-
Equal braking effort to all the four wheels.
Less rate of wear due to absence of joints.
By just changing the size of one piston and cylinder, force can be increased or decreased.
Disadvantages:-
Leakage of brake fluid spoils the brake shoes.
Even the slightest presence of air pockets can spoil the whole system.
It consists of following main parts: (i) Master cylinder (ii) Wheel cylinder (iii) Brake fluid (or brake oil) pipelines.
It consists of a master cylinder which is connected to four cylinders through a pipeline. The wheel cylinder consists of brakes and shoe arrangement.
PRINCIPLE : It works on the principle of Pascal's law, which states that "The confined liquid transmits pressure intensity equally in all directions."
WORKING : When the driver depresses pedal, the effort is transmitted through rod to piston of master cylinder. The piston moves in the cylinder and compress return spring forcing out the fluid from the cylinder into brake line through a by-pass. Piston of a brake cylinders are acted upon by the fluid and press against shoes, bringing their linings tightly against the working surfaces of the drums as soon as the pedal is released, the return spring pushes piston back. At the same time, the compression springs of the brake shoe move pistons to their initial position and the fluid begins to the flow in the reverse direction.