CDL Air Brakes TestAir Brake System PartsEasy
A driver is performing a pre-trip inspection and notices that the brake drums on the drive axle are cracked. What type of brake component is the brake drum?
- AA component of the foundation brakes.
- BAn air storage tank component.
- CA part of the anti-lock braking system (ABS).
- DA part of the air compressor assembly.
Show answer & explanationAnswer & explanation
Correct answer: A. A component of the foundation brakes.
Brake drums, along with brake shoes and linings, are key components of the foundation brakes. Foundation brakes are the mechanical parts at each wheel that directly apply friction to stop the vehicle when air pressure is supplied to the brake chambers.
Why the other options are wrong
- B. Brake drums are part of the wheel-end braking mechanism, not air storage.
- C. ABS is an electronic control system that modifies the action of the foundation brakes, but the drum itself is not an ABS component.
- D. The air compressor assembly generates air pressure; brake drums are at the wheels.
Foundation Brakes
Foundation brakes are the mechanical components at each wheel that convert air pressure into friction to stop the vehicle, including drums, shoes, and linings.
- Directly stop the wheels.
- Consist of drums/rotors, shoes/pads, and linings.
- Actuated by brake chambers.
Memory trick: Foundation: the 'feet' that stop the vehicle.