Subject: Automobile Engineering

Topic: Brakes, Steering & Front Axles

Difficulty: Low

The hydraulic brakes & system is silent, flexible & self lubricating as compared to mechanical brakes. Also this system is highly efficient, durable & simple in design. The hydraulic braking system based on pascal law which states that the fluid transmit pressure equally in all direction without any loss. This system is design in such a way that even brakes are in released position, a small pressure must be maintained in pipeline to protect the entering of air in the system when cup of wheel cylinder are kept expanded. This system consists of master cylinder, wheel cylinder, steel pipe, flexible hose, brake linkage & a check valve at the end master of cylinder.
When operator pressed the brake pedal, this force is transmitted to the piston in master cylinder through linkage. The piston in master cylinder moves by compressing return spring. As bypass port is covered, a further movement of piston build up pressure in the compression chamber, when sufficient pressure is built up, the fluid check valve deflects & fluid under pressure in the pipeline enters in wheel cylinder.
As soon as the fluid enter in wheel cylinder,exert a pressure on two piston to move the piston outward motion of piston causes the brake shoe expand creating tension in retracting spring. The brake shoe lining press tightly against internal surface of brake drum. This friction between brake lining & drum, slow down or stop the rotation of drum hence vehicle slow down & stopped.
As the brake pedal released, the retracting spring pull the brake shoe inward original position, this causes the piston in wheel cylinder pushes back. Due to this the brake fluid flow in reverse direction ie. to master cylinder & to fluid reservoir. As the pressure drop in the fluid line to the fluid check valve at the end of master cylinder closes.