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 Montana 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 have 20 minutes to correctly answer a minimum of 16 questions. The Combination test is not a replacement for the Double/Triple endorsement test.
Number of Question
Passing Score
15. What does the trailer air supply control look like?
Explanation
On newer vehicles, the trailer air supply control is an eight-sided red knob. It's used to control the tractor protection valve.
16. When uncoupling a trailer, landing gear should be:
Explanation
Landing gear, or trailer supports, should always be completely raised before a vehicle is driven. When uncoupling, landing gear should be lowered to make firm contact with the ground. If a trailer is loaded when it is being uncoupled, you should lower the landing gear and turn the crank a few additional times to remove some weight from the trailer.
17. Simply changing lanes can cause:
Explanation
Due to the "crack-the-whip" effect caused by rearward amplification, changing lanes too quickly in a combination vehicle can result in a rollover.
18. An Anti-Lock Braking System (ABS):
Explanation
The function of an Anti-Lock Braking System (ABS) is to prevent a vehicle's wheels from locking up during hard braking.
19. If oil and water build up in your vehicle's air tanks, the brakes:
Explanation
Air tanks should be drained daily to remove water and oil buildup. An excess of oil and water in the air tanks can interfere with proper brake function.
20. Pull out the trailer air supply control to test:
Explanation
