The brake booster is the device that decreases the brake
pedal effort by the assist of vacuum, renaming the common brake as Power brake.
The power brake works on the principle of pressure difference in brake booster.
The
brake booster has two chambers vacuum chamber and pressure chamber. Initially
when brake pedal is free the power booster is completely vacuum on both sides
of diaphragm (both chambers) and there is no entry of atmospheric air into any
chamber of brake booster. The vacuum is created by connection of brake booster
with the intake manifold of the engine, the suction of air by the engine
pistons. When the brake pedal is pressed the vacuum chamber is sealed up and
the atmospheric air is pressurized into the pressure chamber. The vacuum
chamber having very low pressure and pressure chamber with high pressure
assists the brake pedal motion from high pressure to low pressure. The diaphragm
bends and further pressurizes the master cylinder thus brakes are applied.
NOTE:-
AS THE VACUUM IS CREATED BY ENGINE, THE BRAKE BOOSTER DOES NOT WORK WHEN ENGINE IS TURNED OFF. BRAKE PEDAL CAN BE PUSHED SMOOTHLY ONCE AND THE SECOND TIME ITS MUCH HARDER TO PUSH AS NO MORE VACUUM EXISTS.
