Repeatedly pressing and releasing (fanning) the brake pedal may result in?

• A. A loss of air pressure
• B. Increased braking efficiency
• C. Reduced brake wear
• D. Improved control

Answer: (A)

Fanning the brakes uses up stored compressed air faster than the system can replenish it. In a vehicle with an air brake system, braking relies on air stored in the tanks; when you repeatedly press and release the pedal, each brake application consumes air. If this happens rapidly, the compressor may not have time to rebuild the pressure, so the overall air pressure in the system drops. If the pressure gets too low, braking power diminishes and the warning systems or even the emergency brakes can activate. That’s why the best answer is that repeatedly fanning the brake pedal can lead to a loss of air pressure.

The other options don’t fit because pumping the brakes doesn’t increase braking efficiency or reduce wear; in fact, it tends to cause more wear and can worsen control as the system pressure drops.