Air Brake Practice Test

In an air brake system, "service brakes" refer to the primary brakes that are employed during standard vehicle operation. These brakes are designed to slow down or bring the vehicle to a stop when the driver applies pressure to the brake pedal. They are the most commonly used braking mechanism and are crucial for everyday driving situations.

Service brakes are activated by the air pressure in the system, which controls the brake chambers at each wheel; when the brake pedal is pressed, air is released to activate the brakes. This allows the driver to maintain control of the vehicle while driving under normal conditions, providing the necessary stopping power efficiently and effectively.

The other choices refer to different types of braking systems that serve distinct purposes. Emergency brakes are specifically designed for sudden stops in case of a primary braking failure, auxiliary brakes provide additional stopping power, typically during long descents, and parking brakes are meant to keep the vehicle stationary when parked. Each of these systems plays an important role in vehicle safety and operation, but they do not fulfill the primary function of the service brakes during regular driving.