Philadelphia Drivers License Practice Test

Why should you avoid fanning the brakes on a truck with air brakes?

1. It helps cool the brakes

2. It causes loss of air pressure

3. It improves stopping power

4. It reduces wear on the brakes

The correct answer is: It causes loss of air pressure

Avoiding fanning the brakes on a truck equipped with air brakes is crucial because this action can lead to a loss of air pressure. When you rapidly apply and release the brakes, it can cause the air pressure in the brake system to drop. This is problematic because air brakes rely on maintaining sufficient air pressure to function effectively. If the pressure drops too low, the brakes may not engage properly, compromising safety and control of the vehicle. Moreover, fanning the brakes does not enhance stopping power or reduce wear on the brakes; instead, it can lead to inconsistent braking performance and potential brake failure. It can also create excessive heat which is counterproductive for cool braking systems. Understanding air brake operation is essential for safe driving in heavy trucks, where effective braking is vital for preventing accidents.