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 California Commercial Driver.. 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 California Commercial Driver Handbook. 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 17 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question 20

Passing Score 17

1. Trailers with low underneath clearance may be difficult to drive:

On interstate highways.

Over railroad crossings.

On dirt roads.

At the posted speed limit.

Railroad-highway crossings may be difficult to cross when pulling a trailer with a low underneath clearance. In particular, both low-slung units and single-axle tractors pulling long trailers are especially challenging to drive over raised crossings.

2. After connecting the air lines to the trailer while coupling, you should:

Supply air to the trailer.

Chock the wheels.

Inspect the fifth wheel.

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. After connecting the air lines to the trailer while coupling, you should supply air to the trailer.

3. When entering or crossing traffic while driving a combination vehicle, it is especially important that you:

Sound your horn.

Make sure there is a large enough gap for your vehicle.

Expect other drivers to make room for your vehicle.

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 enough gap in traffic for you to safely do so.

4. Trailers built before 1975 are:

Required to have spring brakes.

Not required to have spring brakes.

Unsafe to drive.

Trailers built before 1975 are not required to have spring brakes. When parking a trailer without spring brakes, be sure to use wheel chocks to prevent the trailer from rolling.

5. Test the tractor protection valve by:

Removing the air supply knob.

Removing the parking brake control knob.

Releasing air with the brake pedal.

Releasing air with the gas pedal.

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.

6. If an air supply control is in its "emergency" position:

The vehicle will increase speed.

The trailer emergency brakes will be applied.

The air supply to the trailer will increase.

Tractor protection controls in older vehicles may be operated by levers instead of knobs. If an air supply control is set in its "emergency" position, the air supply will be stopped and the trailer emergency brakes will be applied.

7. Avoid needing to make sudden lane changes by:

Using your horn to encourage other drivers to move out of your lane.

Only driving slower than the posted speed limit.

Watching the road ahead while driving.

Making a sudden lane change can be dangerous when driving a combination vehicle. Avoid the need to make a sudden lane change by looking down the road for upcoming obstacles that will require you to change lanes.

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