Monday, May 1, 2017

CDL Combination Endorsement - Exam 3 - 36 Questions

Combination Endorsement
By Gary Boutin

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

a.  Both hands firmly on the steering wheel.
b. The cargo as close to the ground as possible.
c. The fifth wheel free play as small as possible.

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

a. Trailer emergency brakes to come on.
b. Trailer tank pressure to be lost.
c. Tractor spring brakes to lock on.

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

a. Down.
b. Up.
c. Normal.

4. The tractor protection valve will close and the trailer emergency brakes will  come on when there is a major leak in the ____ brake lines.

a. Service.
b. Parking.
c. Emergency.

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

a. 1.
b. 2.
c. 3.
d. 4.

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

a. Turn wide before you start your turn.
b. Turn wide as you complete your turn.
c. Not make that turn.

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

a. Trailer brakes are locked.
b. Air supply knob is in.
c. Air brakes are off.

8. After you lock the kinpin into the fifth wheel, you should check the connection by pulling:

a. Forward 50-feet, turning right and left.
b. The tractor ahead sharply to release the trailer brakes.
c. The tractor ahead gently with the trailer brakes locked.

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

a. The hand valve applies the tractor brakes instead of the trailer brakes.
b. You could drive away with no trailer brakes.
c. The brake lights will not come on when you press the brake pedal.

10. To stop a trailer skid, you should:

a. Use the trailer hand brakes.
b. Release the service brakes.
c. Countersteer.

11. Loss of air pressure in the emergency lines causes:

a. The relay valves to close.
b. An increase in air pressure to the service line.
c. The trailer's emergency brakes to come on.

12. 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?

a. It should not be done.
b. It results in less skidding than using the brakes pedal alone.
c. Is is the best way to brake and keep the truck in a straight line.

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

a. Back up gently to ease pressure on the fifth wheel locking jaws.
b. Begin to lower the trailer landing gear.
c. Immediately put on your tractor parking brakes.

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

a. Empty.
b. At normal pressure.
c. Between 60 and 80-psi.

15. You supply air to the trailer tanks by:

a. Pushing in the trailer air supply valve.
b. Pulling out the trailer air supply valve.
c. Connecting the service line gland hand.

16. Gland hands are use to connect the:

a. Electric lines from the truck to the trailer.
b. Kingpin from the tractor to the locking jaws on the glide plate.
c. Service and emergency air lines from the truck to the trailer.

17. For a coupling to be complete, the safety catch for the fifth wheel, locking lever must be:

a. Straight up.
b. Through the locking lever.
c. Over the locking lever.

18. Which part of the kingpin should the locking jaws close around:

a. The shank.
b. The head.
c. The base.

19. For a coupling to be complete, the safety catch for the fifth wheel locking lever must be:

a. Straight up.
b. Through the locking lever.
c. The base.

20. Why should you be sure that the fifth wheel plate is greased as required?

a. To ensure good electrical connectors.
b. To prevent steering problems.
c. To reduce heat and noise.

21. When should you user the hand valve to park a combination vehicle:

a. To park at loading docks.
b. To park on a grade.
c. Never.

22. The trailer air supply control or tractor protection valve control should automatically close when the air pressure falls to between ___ psi.

a. 20 and 45.
b. 60 and 85.
c. 100 and 125.

23. The best way to tell if your trailer has started to skid is to:

a. Hear the wheel skidding.
b. See it in your mirrors.
c. Feel for the pulling from the truck cab.

24. When coupling, the proper position of the fifth wheel is:

a. Level with the ground.
b. Titled up towards the end of the tractor.
c. Titled down towards the end of the tractor.

25. If the spring brakes don't release when you push the trailer supply control, you should:

a. Check the air lines connections.
b. Cross the air lines.
c. Check the electrical service cable.

26. The front trailer supports are up and the trailer is resting on the tractor. Make sure:

a. There is enough clearance between the upper and lower fifth wheel.
b. The safety latch is in the unlocked position.
c. There is enough clearance between the the tractor frame and landing gear.

27. When should you use chocks to park a trailer not equipped with spring brakes.

a. Never.
b. Always.
c. Only when it will be parked on an incline.

28. You want to inspect the trailer support. You should place the tractor transmission in which gear after you uncoupled the trailer?

a. Low reverse.
b. Neutral.
c. High reverse.

29. You are coupling a semitrailer to your tractor but have not yet backed under it. The trailer is at the right height when:

a. The kinpin is under about 1 1/4-inches above the fifth wheel.
b. The end of the kingpin is even with the top of the fifth wheel.
c. It will be raised slightly when the tractor is backed under it.

30. After you supply air to the trailer, make sure the air lines are not crossed and the trailer brakes are working. You do this by:

a. Turning on the parking brakes from the cab.
b. Watching your mirrors to see if the trailer lights come on.
c. Applying and releasing the trailer brakes and listening for brake sounds.

31. Which of these statements is true?

a. The brakes and suspension system of combination vehicle work best with a light load.
b. Light vehicle loads need more braking power to stop than heavy ones.
c. Bobtail tractor can take longer to stop than a combination vehicle.

32. A king pin is:

a. The pin which locks the air brake lines together.
b. A pin which locks the trailer to the tractor on the fifth wheel.
c. A pin which holds the wheels on the axles.
d. The pin a driver receives for safe driving.

33. Which of the following steps comes first?

a. Apply the trailer brakes.
b. Raise the landing gear.
c. Put the transmission in reverse.
d. Connect the air supply lines.

34. Before you begin coupling:

a. Check the condition of the tractor frame.
b. Check your path for hazards.
c. Re-position the fifth wheel.
d. Put the spring brakes on.

35. The trailer air supply control:

a. A red triangular-shaped knob.
b. A yellow square knob.
c. A red square knob.
d. A red eight sided knob.

36. The fifth wheel should be checked to see if:

a. There is damage or missing parts.
b. It is properly greased.
c. The jaws are open.
d. All of the above.

Question 32 to 36 were obtained from Trucker Country.


1. b
2. a
3. c
4. c
5. c
6. b
7. a
8. c
9. b
10. b
11. c
12. a
13. a
14. b
15. a
16. c
17. c
18. a
19. c
20. b
21. c
22. a
23. b
24. c
25. a
26. c
27. b
28. b
29. c
30. c
31. c
32. b
33. a
34. b
35. d
36. d

Note: All the test have duplication questions sometimes with different wording. Some tests more than other, because the DMV want to make sure you understand these area of the commercial driving exams.
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