Which action is correct when parking an air-braked vehicle?

Which action is correct when parking an air-braked vehicle?

• A. Rely on service brakes to hold the vehicle
• B. Apply the parking brake when the vehicle is parked
• C. Turn off the engine and release the brakes
• D. Park without using the parking brake on a hill

Answer: (B)

When you park an air-braked vehicle, you must use the parking brake to hold the vehicle in place. The parking brake is a separate system from the service (foot) brakes and is designed to keep the vehicle stationary after you exit or when air pressure may drop. Relying on the service brakes to hold the vehicle is unsafe because they can fade or fail, especially on a grade. Turning off the engine and releasing the brakes would release the parking brake, letting the vehicle roll. Parking on a hill without applying the parking brake is also unsafe. So the correct action is to apply the parking brake whenever the vehicle is parked.