Brake Pressure Alleviation System
The equipment used to help alleviating brake pressure is brake booster, operated by a vacuum system. There is a diaphragm inside the brake booster, and a pipe that connects the brake booster to the intake manifold. When the engine is running, the air intake from the manifold is being sucked in for combustion, while at the same time the air from the brake booster is being sucked in as well. As a result, the air pressure in the brake booster is lowered to the point closer to vacuum. When the driver needs to slow down or come to a stop, he/she will step on the brake pedal. At that point, the metal rod attached to the brake pedal will move and press the air valve of the brake booster to open, quickly letting the outside air in. The air will then push the diaphragm that is attached to the master cylinder pedal, which will then move and press on the piston in the master cylinder the same time the driver’s foot is pressing on the brake pedal.
As a result, the driver will feel only a gentle press on the pedal of the brake. When the driver releases his/her foot from the brake pedal, the pedal will return to its original position. The air valve of the brake booster will close, while the air inside the brake booster continues to be sucked out and utilized consistently until the engine is turned off.
In the case that the engine is turned off, the vacuum condition inside the brake booster remains. As such, after the engine has been turned off, you will continue to feel the gentleness of the brake pressure only after 2-3 pressings, as the air outside of the brake booster will flow inside, while there is no air sucking activity from the brake booster for further usage (because the engine is not running, and hence, no air intake activity). When the air is filled up inside the brake booster, there is no pressure from the brake booster to help pressing the piston in the master cylinder. Therefore, the driver will have to apply more pressure on the pedal of the brake as a result.