Air Brake Practice Test

The correct approach to determine if the spring brakes come on mechanically involves releasing the parking brake and pressing the brake lever repeatedly. This method allows for a clear observation of the spring brakes engaging and disengaging, which is crucial in understanding their function within the braking system. When the parking brake is released, pressing the brake lever demonstrates whether the mechanics are operating correctly, ensuring that the system responds as intended. Other options may not effectively test the mechanical function of the spring brakes. For example, applying the parking brake and pressing the brake pedal could indicate whether the service brakes are functioning but does not specifically test the mechanics of the spring brakes themselves. Hitting on the brakes while traveling at a high speed can create unsafe conditions and does not provide a reliable method to assess mechanical engagement. Continuous pressing and releasing of the parking brake may not clearly delineate the mechanical function of the spring brake system either, as it primarily tests the parking brake operation rather than the response of the spring brakes.