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
19. What color are ABS malfunction lamps?
Explanation
Vehicles with Anti-Lock Braking Systems (ABS) have yellow malfunction lamps.
20. Before starting down a hill, be sure to:
Explanation
Before starting down a hill, be sure to switch into a low gear. Gravity will increase your vehicle's speed as you travel downhill.
21. What do air brakes use to make the brakes work?
Explanation
Many large CMVs are equipped with air brakes. An air braking system uses compressed air to operate.
22. If a trailer begins to skid, the driver should:
Explanation
If your trailer starts to skid while you are braking, you should release the brakes and allow them to begin to regain traction. Once its wheels have regained their grip on the road, the trailer will begin to straighten out and follow the tractor.
23. What is a wig wag?
Explanation
A wig wag is a type of low air pressure warning device in an air brake system. It drops a mechanical arm into the driver's view when the air pressure in the tanks falls below 60 psi.
24. A trailer that is too high:
Explanation
Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.
25. If color-coded, which color is used to identify service lines?
Explanation
