Air Brakes
This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice questions. Each question has two, three or four possible answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Minnesota Commercial Driver’s Manual. Questions come from the chapters covering: Air Brakes and Combination Vehicles. The Air Brakes endorsement may be used with the Class A, B or C CDL.
Number of Question
Passing Score
7. If colors are being used to distinguish glad hands, which color is used for emergency lines?
Explanation
When trailer air lines are color-coded, the service lines are generally blue and the emergency lines are generally red.
8. Which type of vehicle is most prone to the “crack-the-whip” effect?
Explanation
Triple combination trailers are most vulnerable to the "crack-the-whip" effect.
9. Air brakes use ____ to function.
Explanation
The brakes in an air brake system use compressed air to function properly.
10. If the low pressure warning signal activates while you are driving, you should:
Explanation
If the low pressure warning signal activates while you are driving, it is important that you safely exit the roadway as soon as possible and park your vehicle. If the air pressure gets too low, the brakes will no longer work well enough for you to stop safely.
11. What happens when the wheels of a trailer lock up?
Explanation
A trailer tends to swing around, potentially resulting in a trailer jackknife, if its wheels lock up.
12. Rollovers happen when:
Explanation
