About Brake Boosters
While we are normally familiar with the function of brake rotors and how brake pads work, the brake booster is often a foreign object only a few had the honor to tinker with. This mysterious, cylindrical, black object is usually located in the back of the engine bay near the firewall. If you were to visualize a flow chart of what happens after your press down your brake pedal, the brake boost would be the first major component that it would have to go through.
Let's visualize this. You are approaching a red light and step on your brake pedal. The force your foot exerts onto the brake pedal, let's say 100lbs, which then needs to be transferred and divided to each of the four brake calipers. That leaves us without much force to actually clamp the brake pads to slow down the brake rotors. Keep in mind most cars weigh 3-4 tons. Enter brake boosters. Their purpose is to reduce the effort required to stop the car, efficiently. In other words, they turn your human powers into super human powers that can stop a car.
The brake booster acts as part of the master cylinder setup and it uses the vacuum from the engine intake to boost its pressure exerted onto the brakes themselves, or sometimes it may use an external vacuum unit, in applications like diesel engines.Possible Symptoms
Ensuring proper brake booster operation is vital to proper brake operation. The brake booster should not be leaking and you shouldn't be using excessive force trying to stop the car in normal driving situations. In most cars, the brake pedal should sink to the floor a little if you are pressing it down prior starting the engine.