Arizona Air Brakes CDL Practice Test

What happens if you apply the parking brake while the brakes are hot?

1. The brake pads could warp

2. The vehicle will stop immediately

3. The air pressure will increase

4. Nothing will happen

The correct answer is: The brake pads could warp

When the parking brake is applied while the brakes are hot, the brake pads can indeed warp. This is due to the heat generated during braking, which causes the materials in the brake pads and rotors to expand. If the parking brake is engaged while the brakes are still in a heated state, it can cause uneven cooling or distortion of the brake components as they cool down. This process can lead to warping, which diminishes braking efficiency and may result in additional wear and tear, creating further issues down the line. In contrast, if the vehicle stops immediately, it is typically due to the act of applying the brakes, not the state of the parking brake. Likewise, air pressure increasing is not a result of simply applying the parking brake; instead, it pertains to the functioning of the air brake system. Finally, suggesting that nothing will happen under these conditions overlooks the potential for damage to the brake components, which is a significant risk when the parking brake is applied to hot brakes.