What is a common consequence of fanning the brake pedal?

• A. Increased braking efficiency
• B. A loss of air pressure
• C. Reduced stopping distance
• D. ABS integration

Answer: (B)

In air-brake systems, braking power comes from stored air pressure. Pressing the brake pedal opens the valve to send air to the brake chambers, and releasing vent air away. When you “fan” the brakes by rapidly pumping the pedal, you’re repeatedly venting and recharging the system faster than the compressor can keep up. This can cause the overall air pressure in the system to drop, so the brakes lose effectiveness. That loss of pressure is the common consequence of fanning the brake pedal. It isn’t about somehow increasing efficiency or shortening stopping distance, and ABS isn’t a direct result of pumping the pedal—it’s a separate system that activates based on wheel speed.