What may happen if you repeatedly press and release (fan) the brake pedal?

Pressing and releasing the brake pedal repeatedly, a practice known as "fanning" the brake, can lead to a loss of air pressure in the brake system. Air brake systems rely on a certain level of pressure to function effectively. Each time the brake pedal is pressed, air is drawn from the system to engage the brakes. If this process is repeated excessively, it can exhaust the air reserves available, resulting in a drop in air pressure.

When the air pressure is reduced, the brakes may become less effective or may fail to engage properly, increasing the risk of an accident. Maintaining adequate air pressure is crucial for the reliable operation of air brakes, so understanding the implications of fanning the brakes is essential for all drivers, particularly those operating commercial vehicles with air braking systems.