Instructions

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 Commercial Drivers License.. Read More

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 Commercial Drivers 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 20

Passing Score 16

1. Before a drive, ensure that air flows to all trailers by:

Opening the rear shut-off valves and listening for escaping air.

Closing the rear shut-off valves and listening for escaping air.

Disconnecting air supply lines and listening for escaping air.

Rolling each trailer down a hill and testing the brakes.

Before a trip, ensure that air in the air brake system reaches all trailers. Do this by waiting for air pressure to build, then sending air to both the emergency and service lines and opening the shut-off valves on the rear of the last trailer. If air escapes from the shut-off valves in the rear of the combination, the air is being supplied to the entire vehicle.

2. To prevent a rollover, a driver should:

Keep cargo low.

Place cargo high.

Keep cargo loose.

Turn quickly.

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.

3. What is the Johnson bar?

A hand valve that works the trailer brakes

A valve that indicates the fuel level

A valve that measures the amount of liquid in the air brake system

A valve that allows for the release of excess pressure in the braking system

The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It should be used only to test the brakes.

4. When driving a trailer with ABS, you should:

Not depress the brakes as much as you would when driving a vehicle without ABS.

Use extra braking force to ensure the ABS kicks in.

Brake as you would when driving a vehicle without ABS.

Try to not brakes as often as you would when driving a vehicle without ABS.

When driving a tractor-trailer combination equipped with an Anti-Lock Braking System (ABS), you should brake in the same manner that you would if operating a vehicle without ABS.

5. Large combination vehicles take the longest amount of time to stop:

When fully loaded.

When partially loaded.

When empty.

When mostly loaded.

Large combination vehicles take longer to stop when they are empty than when they are loaded. The decreased weight causes a vehicle's wheels to have decreased traction on the surface of the road.

6. The trailer hand valve should be used:

Regularly to activate the trailer brakes in all driving conditions.

Only to test the trailer brakes.

Only in inclement weather when the trailer may skid.

Only if the trailer is carrying a load.

The trailer hand valve should be used only to test the trailer brakes. It should not be used while driving because it may cause the trailer to skid.

7. Pull out the trailer air supply control to test:

The parking brake.

The trailer emergency brakes.

The trailer service brakes.

The landing gear.

Be sure to test the trailer emergency brakes before beginning a trip. After ensuring that the trailer rolls freely, you can test the emergency brakes by pulling out the trailer air supply control, or placing it in the "emergency" position. Pull forward slightly with the tractor and make sure the trailer does not move.

Grade This Section

See the exact questions that will be on the 2024 North Dakota DMV exam.

99.2% of people who use the cheat sheet pass the FIRST TIME

Click Here
Full Cheat Sheet Unlock Your Exclusive Cheat Sheet!