The vacuum brake booster boosts the force applied by the pedal onto the master cylinder that do the brake pedal less hard and more effective on the braking capability. It is used to do driver`s work more light by the braking and it`s the reason doing the less braking distance.
Vacuum Brake Booster Construction
Vacuum Brake Booster consists of housing, two parts of that are – base 13 and cap 10 is divided with membrane. Membrane fixes by support disk 1 and support ring 8. The support disk consists of twelve separate steel sectors, which are inserted into the pockets of the shell and secured with a fixing washer. A central rubber valve 4 is inserted into the hole of the central support disk, which performs the functions of vacuum and air valves in the booster.
The outer edges of the membrane 12 serve as a gasket and are sandwiched between the cover 10 and the base 13 of the booster housing, and the inner part of the membrane is fixed to the piston 15.
The piston 15 has two annular projections at front end; the outer annular protrusion is as a socket for the vacuum valve, and the inner one is for the air valve.
The piston 15 is connected to the stem 6 using the adjusting screw 21. In this case, the support plate 2 and the central valve 4 with the support disk are clamped between the lock washer 5 and the piston 15, and the return spring presses the central part of the valve 4 to the inner end of the piston.
On the other side, the pusher 17 enters to the piston; the hinged tip is mounted in the support 14, is fixed in the piston by the pressure sleeve 16. The pusher of the fork 19 is connected to the brake pedal, and the rod 6 transfers force to the brake master cylinder.
The support plate 2 together with the amplifier membrane 12 with a return spring 7 is constantly pressed against the annular stop 22. The position of the piston 15 in the base 13 of the amplifier housing is fixed by the guide ring 20.
The cavity 1 of the amplifier in front of the membrane through the check valve 9 and the hose is constantly connected to the inlet pipe of the engine, and the cavity 2 can be connected either with the atmosphere or with the cavity 1.
The non-return valve 9 is open when there is a vacuum in the intake pipe and closes when the pressure in it increases above atmospheric pressure to prevent the mixture from the engine from getting into the vacuum booster.