Combination
All applicants who are applying for a Class A CDL should be prepared to take the Combination test. This test covers information found in Section 6 of the Arizona Commercial Driver License Manual. Section 6 provides the information needed to safely operate tractor-trailers, doubles, triples, and straight trucks with trailers. The test is made up of 20 multiple-choice questions, and applicants will need to correctly answer a minimum of 16 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.
Number of Question
Passing Score
15. A driver should test the tractor protection valve by:
Explanation
You should test the tractor protection valve by allowing the air supply to properly charge, turning off the engine, then releasing air from the system by pressing the brake pedal several times. The tractor protection valve should move into its emergency position when psi drops to an unsafe level.
16. Keeping cargo low can:
Explanation
Rollovers can happen when a combination vehicle is turned too quickly. To help prevent the risk of rollover, it is important to keep the vehicle's center of gravity low by loading cargo as close to the ground as possible.
17. A tractor protection valve:
Explanation
A tractor protection valve keeps air in a tractor or truck air brake system should the trailer break away or develop a bad leak. The valve will close automatically if the pressure drops to an unsafe level.
18. If you must cross traffic while driving a combination vehicle, you should:
Explanation
Combination vehicles require more space on the road than other vehicles. When entering or crossing traffic while driving a combination vehicle, it is especially important that there is a large enonugh gap in traffic to safely do so.
19. When driving a vehicle equipped with an Anti-Lock Braking System (ABS), brakes should be applied:
Explanation
When driving a vehicle with ABS, you should brake in the same manner as you would in a vehicle without ABS.
20. Older trailers are not equipped with spring brakes. This means that if the air supply for a vehicle's air braking system leaks away:
Explanation
