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 Driver 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 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 25 multiple-choice questions, and applicants will need to correctly answer a minimum of 20 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question 25

Passing Score 20

13. Using the trailer hand valve while driving:

Will help you turn safely.

Will stop your trailer safely.

Can cause a skid.

Is impossible.

Never use the trailer hand valve while operating your vehicle. Using the trailer hand valve while driving can cause your trailer to skid.

14. The trailer hand valve:

Should always be used for parking.

Should only be used for parking on a downhill.

Should never be used for parking.

Should only be used when transporting cargo.

The trailer hand valve should not be used for parking. This could cause all of the air to leak out of the braking system, resulting in the brakes releasing. Instead, use the parking brake.

15. Combination vehicles need extra space on the road because they:

Drive more slowly than other commercial motor vehicles.

Are heavier than other commercial motor vehicles.

Need more space to turn and stop than other commercial motor vehicles.

Combination vehicles need more space on the road than other commercial vehicles because they are longer and need more space to turn and stop. It is especially important to properly manage space when you are operating a combination vehicle.

16. In a vehicle equipped with an automatic tractor protection valve, the valve will pop out when:

Air pressure drops to a level between 20 and 45 psi.

You are experiencing a trailer jackknife.

Wheels have regained traction after a skid.

Air pressure is above 45 psi.

In vehicles equipped with an automatic tractor protection valve, the valve will pop out if air pressure drops to a level between 20 and 45 psi. When the valve pops out, the protection valve will close, stopping the flow of air.

17. If unsure if a trailer is equipped with ABS, you can:

Check under the trailer for wheel speed sensors coming from the back of the brakes.

Try driving on a slippery surface and see if ABS kicks in.

Assume it does have ABS.

Remove a tire and look for the ABS sensor on the axle.

Trailers and converter dollies built on or after March 1, 1998 are required to have Anti-Lock Braking Systems (ABS). This will be indicated by the presence of a yellow malfunction lamp. You can determine if older trailers have ABS by checking under the trailers for ECU and wheel speed sensor wires coming from the back of the brakes.

18. What happens when the wheels of a trailer lock up?

The trailer will usually continue to move in a straight line.

The trailer will disengage.

The trailer will likely swing around.

The trailer will stop.

A trailer tends to swing around, potentially resulting in a trailer jackknife, if its wheels lock up.

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