Air Brake Practice Test

The service brake system is designed specifically to apply and release the brakes when the driver engages the brake pedal. This system is responsible for the normal braking function while driving, allowing the driver to control the vehicle's speed and stop safely under typical operating conditions. In contrast, the parking brake system functions independently of the service brake system. It is primarily used to keep the vehicle stationary when parked and is not intended for regular use while driving. The emergency brake system, while it can engage the brakes in a scenario where the service brakes fail, typically operates differently from the service brakes and is not meant to be applied during normal driving situations in the same manner as the service brake. Thus, the service brake system remains the only one directly controlled by the driver using the brake pedal during regular operation.