Two technicians are discussing vacuum brake boosters. Technician A says that when the engine is running and the driver's foot is off the brake pedal, a vacuum is present on both sides of the booster diaphragm. Technician B says that when the brakes are in the applied position, vacuum is present on the front side of the diaphragm. Which technician is correct?

Question

Quizplus · Accepted Answer

Both technicians are correct. When the engine is running and the brake pedal is not pressed, vacuum is present on both sides of the diaphragm. When the brakes are applied, vacuum is maintained on the front side while atmospheric pressure is allowed on the rear side to assist braking.

Two Technicians Are Discussing Vacuum Brake Boosters