Sample Commercial Driver License Knowledge Test

(From the 2003 Commercial Driver Handbook)

Directions:  Choose your answer from the three possible answer choices and mark an X in the box across from your choice.  Please do not talk, use any books or notes, or leave the test area with your test before it has been graded; to do so may result in a test failure and your driving privilege may be suspended or revoked.

A list of answers is given at the bottom of this test.

Section 2:  Combination (Class A) Vehicles Test

Passing Grade -- 3 errors or less

1. The air leakage rate for a combination of two vehicles (engine off, brakes off) should not be greater than _____ psi or less in one minute.

   1. 2

   2. 3

   3. 4

    

2. After you lock the kingpin into the fifth wheel, you should check the connection by pulling:

   1. Forward 50 feet, turning right, and left

   2. The tractor ahead sharply to release the trailer brakes

   3. The tractor ahead gently with the trailer brakes locked

    

3. The tractor protection valve will close and the trailer emergency brakes will come on when there is a major leak in the _____ brake line.

   1. Service

   2. Parking

   3. Emergency

    

4. To stop a trailer skid, you should:

   1. Use the trailer hand brake

   2. Release the service brakes

   3. Countersteer

    

5. You have pushed in the trailer supply valve.  You should not move the tractor until the whole air system is:

   1. Empty

   2. At normal pressure

   3. Between 60 and 80 psi

    

6. After the trailer has been coupled to the tractor, the tractor protection control valve should be placed in the _____ position.

   1. Down

   2. Up

   3. Normal

    

7. Before you back under a truck trailer, make sure the

   1. Trailer brakes are locked

   2. Air supply knob is in

   3. Air brakes are off

    

8. One of the things a driver can do to prevent a rollover is to keep:

   1. Both hands firmly on the steering wheel

   2. The cargo as close to the ground as possible

   3. The fifth wheel free play as small as possible

    

9. Loss of air pressure in the emergency line causes:

   1. The relay valve to close

   2. An increase in air pressure to the service line

   3. The trailer's emergency brakes to come on

    

10. When you get ready to back under a trailer, you should line up:

    1. The left rear outside dual wheel with the kingpin

    2. The kingpin with the edge of the driver's side locking jaw

    3. Directly in front of the trailer

     

11. You are uncoupling a trailer.  After you shut off the trailer air supply and lock the trailer brakes, you should:

    1. Back up gently to ease pressure on the fifth wheel locking jaws

    2. Begin to lower the trailer landing gear

    3. Immediately put on your tractor parking brakes

     

12. You have a major leak in the service line and you put on the brakes.  Service air pressure will escape and cause the:

    1. Trailer emergency brakes to come on

    2. Trailer tank pressure to be lost

    3. Tractor spring brakes to lock on

     

13. What will happen if the air lines are crossed when you hook up to an old trailer with no spring brakes?

    1. The hand valve applies the tractor brakes instead of the trailer brakes

    2. You could drive away with no trailer brakes

    3. The brake lights will not come on when you press the brake pedal

     

14. If you cannot make a turn without entering another traffic lane, you should:

    1. Turn wide before you start your turn

    2. Turn wide as you complete your turn

    3. Not make the turn

     

15. To prevent a jackknife in normal driving, some drivers use the hand valve before stepping on the brake pedal.  Which of these statements is true?

    1. It should not be done

    2. It results in less skidding than using the brake pedal alone

    3. It is the best way to brake and keep the truck in a straight line