Michigan CDL - Air Brakes Practice Exam

When should the parking brake be used in a vehicle with air brakes?

1. Only during long stops

2. Whenever you park your vehicle

3. Only when indicated by a warning signal

4. Never, it's not necessary

The correct answer is: Whenever you park your vehicle

Using the parking brake whenever you park your vehicle is crucial for safety and stability. In vehicles equipped with air brakes, the parking brake is designed to securely hold the vehicle in place when it is stationary. This is especially important because air brake systems can lose pressure over time, and relying solely on the service brakes may not keep the vehicle secure during extended periods of inactivity. The parking brake serves as a fail-safe mechanism—engaging it ensures that the vehicle will not roll away, even on an incline. This practice is especially vital in commercial driving, where the weight and size of the vehicle can pose significant risks if it were to move unexpectedly. In contrast to the other options, which suggest limited use or misunderstanding of the parking brake's purpose, proper use of the parking brake is essential anytime the vehicle is parked, regardless of the length of the stop or other indications. Thus, the clearest and safest practice is to engage the parking brake every time you park your vehicle.