Air Brake Practice Test

What factor can significantly cause brakes to fade or fail?

1. Driving in heavy rain.

2. Excessive use of service brakes.

3. Driving in heavy traffic.

4. Excessive use of emergency brake.

The correct answer is: Excessive use of service brakes.

Excessive use of service brakes can significantly cause brakes to fade or fail due to the heat generated during braking. When brakes are applied frequently or intensely, especially when descending a hill or during stop-and-go traffic, they can overheat. Brake systems rely on friction to slow the vehicle, and if the braking system gets too hot, the brake pads may become less effective, leading to a condition known as brake fade. This reduction in braking efficiency can severely compromise vehicle control and stop distance, posing a safety risk. In contrast, while driving in heavy rain or heavy traffic can create challenges for braking, they do not inherently cause brake fade in the same way that excessive braking does. Similarly, while the emergency brake is designed for situations where the primary brakes fail, its excessive use would typically not lead to fade in the same way as the service brakes under normal driving conditions. Understanding the impacts of heat on brake systems is crucial for maintaining vehicle safety and performance.