When you press the brake pedal, what happens in an air brake system?

When you press the brake pedal, what happens in an air brake system?

• A. Compressed air enters the brake chamber
• B. The engine supplies oil
• C. The parking brake engages
• D. Electrical power is cut

Answer: (A)

In an air brake system, brakes are activated by air pressure. When you press the brake pedal, a valve opens and allows compressed air from the storage tanks to flow into the brake chamber at each wheel. The incoming air pushes a piston inside the chamber, moving the braking shoes or pads against the drum or rotor to create friction and slow the vehicle. The other options aren’t how air brakes operate: there’s no direct engine oil involvement for braking, the parking brake is a separate function usually tied to its own valve, and braking isn’t achieved by cutting electrical power.

In an air brake system, brakes are activated by air pressure. When you press the brake pedal, a valve opens and allows compressed air from the storage tanks to flow into the brake chamber at each wheel. The incoming air pushes a piston inside the chamber, moving the braking shoes or pads against the drum or rotor to create friction and slow the vehicle. The other options aren’t how air brakes operate: there’s no direct engine oil involvement for braking, the parking brake is a separate function usually tied to its own valve, and braking isn’t achieved by cutting electrical power.