DMV PA - CDL Combination Vehicles Multiple Choice Test Questions

1. There are two things that a driver can do to prevent a roll-over. They are: (1) Keep the cargo as close to the ground as possible; and (2):

a. Go slow around turns.
b. Keep both hands firmly on the steering wheel.
c. Make sure that the brakes are properly adjusted.
d. Keep the fifth wheel free-play tight.

2. Which of these statements is true?

a. Always delay braking a heavy vehicle until you have no other choice.
b. The brake and suspension systems of combination vehicle work best with a light load.
c. "Bobtail" tractors can take longer to stop than a combination vehicle loaded to maximum gross weight.
d. Light vehicles need more braking power to stop than heavy ones.

3. In normal driving, some drivers use the hand valve before the brake pedal to prevent a jackknife. Which of these statements is true?

a. It lets the driver steer with both hands.
b. It results in less skidding than using the brake pedal alone.
c. It should not be done.
d. It is the best way to brake and keep the truck in a straight line.

4. When should you use the hand valve to park a combination vehicle?

a. To park at loading docks.
b. To park on a grade.
c. To park for less than two hours.
d. Never.

5. The hand valve should be used:

a. Only with the foot brake.
b. To test the trailer brakes.
c. As a parking brake.
d. Only when the trailer is fully loaded.

6. You supply air to the trailer tanks by:

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

7. Your emergency air line breaks or gets pulled apart while you are driving. The loss of pressure will cause the:

a. Emergency trailer brakes to come on.
b. Tractor's air to dump into the trailer tank through the service line.
c. Air compressor to unload instead of pumping air.
d. Trailer supply valve to open.

8. You are driving a combination vehicle when the trailer breaks away , pulling apart both air lines. You would expect the trailer brakes to come on and:

a. The tractor to lose all air pressure.
b. Go off about every 2 seconds.
c. The trailer supply valve to stay open.
d. The tractor protection valve to close.

9. Air lines on a combination vehicle are often colored to keep from getting them mixed up. The emergency line is _____ and the service line is _____.

a. Orange; Black
b. Black; Yellow
c. Blue; Red
d. Red; Blue

10. Why should you lock the tractor glad hands to each other when you are not towing a trailer?

a. It keeps dirt and water out of the lines.
b. The brake circuit becomes a back up air tank.
c. The air circles back, getting cleaner each cycle.
d. All of the above.

11. What will happen if the air lines are crossed when you hook up to an old trailer?

a. The hand valve will apply the tractor brakes instead of the trailer brakes.
b. The brake pedal will work the trailer spring brakes instead of the air brakes.
c. If the trailer has no spring brakes, you could drive away but you would not have trailer brakes.
d. The brake lights will not come on when you press the brake pedal.

12. Semi-trailers made before 1975 that are equipped with air brakes.

a. Are easier to brake because they are heavier.
b. Often do not have spring brakes.
c. Usually need a glad hand converter.
d. All of the above are true.

13. Air brake equipped trailers made before 1975:

a. Cannot be legally operated on Interstate Highways.
b. Are easier to brake than newer trailers because they are heavier.
c. Usually need a glad hand converter.
d. Often do not have spring brakes.

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

a. Trailer emergency brakes to come on.
b. Trailer's tank pressure to go to the tractor's system.
c. Tractor spring brakes to lock on.
d. Trailer tank pressure to be lost.

15. If the service air line comes apart while you are driving a combination vehicle but the emergency line stays together, what will happen right away?

a. The emergency tractor brakes will come on.
b. Nothing is likely to happen until you try to apply the brakes.
c. The emergency trailer brakes will come on.
d. The trailer's air tank will exhaust through the open line.

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

a. To reduce heat and noise.
b. To prevent steering problems.
c. To keep the brake system in balance.
d. To ensure good electrical connections.

17. When you get ready to back under a semi-trailer you should line up:

a. About 12 degrees off the line of the trailer
b. The kingpin to engage the driver's side locking jaw first.
c. Directly in front of the trailer.
d. The left rear outer dual wheel with the kingpin.

18. You are about to back your tractor under a semi-trailer. The trailer is at the right height when the:

a. Trailer landing gears are fully extended.
b. Kingpin is about 2 inches above the fifth wheel.
c. End of the kingpin is even with the top of the fifth wheel.
d. Trailer will be lifted slightly when the tractor backs under it.

19. You are coupling a tractor to a semi-trailer and have backed up but are not under it. What should you hook up before backing under?

a. The electrical service cable.
b. The ground cable.
c. Nothing; back up and lock the fifth wheel.
d. The emergency and service air lines.

20. You are coupling a tractor and semi-trailer and have connected the air lines. Before backing under the trailer you should:

a. Pull ahead to test the glad hand connections.
b. Make sure that the trailer brakes are off.
c. Supply air to the trailer system, then pull out the air supply knob to lock the trailer brakes.
d. Apply the brakes twice to alert others.

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

a. Air supply knob is in.
b. Trailer brakes are locked.
c. Air brakes are off.
d. Tractor protection valve is normal.

22. After you supply air to the trailer, make sure the air lines are not crossed and the trailer brakes are working. This is done by:

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

23. You should not back a tractor under a trailer until the whole air system is:

a. Between 60 and 80 psi.
b. Bled down to half the maximum pressure.
c. At normal pressure.
d. Empty.

24. After connecting the air lines but before backing under the trailer, you should:

a. Pull ahead to test the glad hand connections.
b. Supply air to the trailer system, then pull out the air supply knob.
c. Make sure that the trailer brakes are off.
d. Walk around the rig to be sure that it is clear.

25. How should you test the tractor-semi-trailer connection for security?

a. Rock the trailer back and forth with the trailer brakes locked.
b. Pull gently forward in low gear against the locked trailer brakes then look at it carefully.
c. Put the tractor in gear and pull ahead with a sharp jerk.
d. Look at it carefully.

26. You are coupling a semi-trailer to your tractor but have not yet backed under. The trailer is at the right height when:

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

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

a. Pulling forward 50 feet, turning right and left.
b. Backing up with the trailer brakes released.
c. Pulling the tractor ahead sharply to release the trailer brakes.
d. Pulling the tractor ahead gently with the trailer brakes locked.

28. How much space should be between the upper and lower fifth wheel after coupling?

a. About 1/4 inch
b. At least 1/2 inch
c. Just enough to see light through it.
d. None.

29. The Fifth Wheel locking lever is not locked after the jaws close around the kingpin. This means that:

a. The trailer will not swivel on the fifth wheel.
b. The coupling is not right and should be fixed before driving the coupled unit.
c. The parking lock is off and you may drive away.
d. You can set the fifth wheel for weight balance.

30. Which part of the kingpin should the locking jaws close around?

A. The base.
B. The shank.
C. The head.
D. It does not matter.

31. The safety catch for the fifth wheel locking lever must be ____________ for a coupling to be complete.

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

32. You have coupled with a semi-trailer. Where should you put the front trailer supports before driving away?

a. 3 turns off the top with the crank handle secured in its bracket.
b. Fully raised with the crank handle secured in its bracket.
c. Raised 3/4 way with the crank handle removed.
d. Raised 1/2 way with the crank handle secured in its bracket.

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

a. There is enough clearance between the tractor frame and the landing gear.
b. There is enough clearance between the tops of the tractor tires and the nose of the trailer.
c. Neither a nor b is correct.
d. Both a and b are correct.

34. The air leakage rate for a combination vehicle (engine off, brakes on) should be less than __ psi.

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

35. The air leakage rate for a combination vehicle (engine off, brakes off) should be less than __ psi per minute.

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

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

a. Empty.
b. Between 60 and 80 psi.
c. Flushed of all moisture.
d. At normal pressure.

37. When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels.
This is called:

a. Sidewinding
b. Jack-knifing
c. Offtracking
d. Off-roading

38. "Cheating" is an informal word for:

a. Sidewinding.
b. Offtracking.
c. Jack-knifing.
d. Off-roading.

39. "Glad Hands" is an informal word for:

a. "Cut Out Cocks"
b. Clutch Pedals
c. Hose Couplers
d. Trailer Tanks

40. "Cut-Out Cocks" is an informal word for:

a. Shut-off Valves
b. Parking Brakes
c. "Glad Hands"
d. Hose Couplers