What is the function of a brake booster?

• A. To measure wheel speed
• B. To regulate brake pad wear
• C. To increase the force applied to the brakes
• D. To cool brake components

Answer: (C)

Brake boosters multiply the force you apply to the brake pedal, making it easier to generate braking pressure. In a vacuum booster, engine vacuum acts on one side of a diaphragm while the pedal pushrod moves the other side, so the difference pushes the master cylinder plunger with extra force. This means you can achieve strong braking without pressing hard. Some systems use electric or hydraulic assist, but the goal is the same: provide added braking force beyond what your leg can do alone. The booster isn’t involved in wheel-speed sensing (that’s for ABS), it doesn’t regulate brake pad wear, and it doesn’t cool brake components.