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CDL Answers > Combination Vehicle > Flashcards

Combination Vehicle Flashcards

1
Q

1) You supply air to the trailer tanks by:

A

pushing in the trailer air supply valve

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2
Q

2) Loss of air pressure in the emergency line causes:

A

the trailer’s emergency breaks to come on

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3
Q

3) A tractor with a ____________ trailer requires the shortest amount of stopping distance.

A

fully loaded

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4
Q

4) Which of these statements is true?

A. the brake and suspension of combination vehicles work best with a light load
B. light vehicles need more braking power to stop than heavy ones
C. bobtails tractors can take longer to stop than fully loaded combination

A

C. Bobtails tractors can take longer to stop than a fully loaded vehicle.

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5
Q

5) If you cannot make a right turn without swinging into another lane, you should:

A

turn wide as you complete the turn

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6
Q

6) The tractor protection valve will close and the emergency brakes will come on when there is a major leak in what air line?

A

Emergency

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7
Q

7) Off tracking or “cheating” causes which of these to follow the widest path while making a turn?

A

3 axle tractor towing a 45 foot trailer

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8
Q

8) If your vehicle gets stuck on a railroad crossing, you should:

A

get out of the vehicle and away from the tracks

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9
Q

9) When driving a set of double trailers, it is necessary to close shut-off valves on some trailers. Where are these valves located?

A

At the back of trailers used to tow other trailers

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10
Q

10) Before you back under a trailer, make sure of what?

A

The trailer brakes are locked

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11
Q

11) To unlock the fifth wheel, you pull the handle to what position?

A

Open

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12
Q

12) After connecting the air lines, but before backing under the trailer, you should:

A

supply air to the trailer, then pull out the trailer air supply valve

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13
Q

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

A

The emergency and service air lines

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14
Q

14) You are coupling a tractor to a trailer. The trailer is at the right hight when:

A

the trailer is raised slightly when the tractor is backed under it

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15
Q

15) Why should you connect the air lines to a dummy coupler when they are not in use?

A

It will keep dirt and water out of the lines

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16
Q

16) The air leakage rate for a combination vehicle engine with the engine offand the brakes off should be less than?

A

3 PSI

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17
Q

17) Air and electric lines from the tractor to the trailer should be:

A

secured properly with enough slack for turns

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18
Q

18)Air brake equipped trailers made before 1975:

A

often do not have spring brakes

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19
Q

19) The hand valves should be used:

A

to test the trailer brakes

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20
Q

20) The air leakage rate for a combination vehicle with the engine off and the brakes on should be less than _____ per minute.

A

4 PSI

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21
Q

21) Your emergency line brakes or gets pulled apart while driving. The loss of pressure will cause the:

A

emergency trailer brakes to come on

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22
Q

22) You have pushed in the trailer air supply valve. You should not move the vehicle until the whole system is:

A

at normal pressure

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23
Q

23) When should you use the hand valve to park a combination vehicle?

A

Never

24
Q

24) The best way to tell that your trailer has started to skid is to:

A

see it in your mirrors

25
Q

25) A trailer is most likely to jackknife when it is:

A

empty

26
Q

26) If the service line comes apart but the emergency line stays together, what will happen right away?

A

Nothing is likely to happen until you apply the brakes

27
Q

27) When backing a tractor under a trailer you should:

A

always use the lowest reverse gear

28
Q

28) After you have coupled the trailer, you should begin raising the landing gear using what gear?

A

Low gear

29
Q

29) You will know the trailer you are using has ASB by:

A

a yellow malfunction lamp on the left side

30
Q

30) If you cross the air lines while coupling to an old trailer what will happen?

A

If the trailer has no spring brakes, you could drive away but you would not have trailer brakes

31
Q

31) When should you get out of your vehicle when you are backing a trailer?

A

When you are unsure of your path of travel

32
Q

32) When you are uncoupling a loaded trailer, you should lower the landing gear until it:

A

Makes firm contact with the ground, then turn it a few extra cranks in lower gear

33
Q

33) How much space should be between the upper and lower fifth wheel after coupling?

A

None

34
Q

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

A

the is enough clearance between the frame and the landing gear

35
Q

35) Why should you be sure the the fifth wheel is greased as required?

A

To prevent steering problems?

36
Q

36) After you lock the kingpin into the fifth wheel, you check the connection by:

A

pulling the tractor ahead gently with the trailer brakes locked

37
Q

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

A

applying and releasing the trailer brakes and listening for sounds

38
Q

38) To be safe while driving, you should at least leave 1 second for every __ feet of vehicle length as following distance.

A

10

39
Q

39) Two things you can do to prevent rolling over are keep the cargo as low to the ground as possible, and:

A

go slow around turns

40
Q

40) You have a major leak in the service line and you put on the brakes. Service air pressure will escape and if it goes low enough will cause:

A

trailer emergency brakes to come on

41
Q

41) When uncoupling a trailer, after you have locked the trailer brakes, you should:

A

back up gently to ease pressure on the fifth wheel jaws

42
Q

42) When do you need to use chokes to park a trailer that does not have spring brakes?

A

Always

43
Q

43) The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means:

A

The coupling is not right and should be fixed before driving.

44
Q

44) When you get ready to back under a trailer, you should line up:

A

directly in front of the trailer

45
Q

45) After you have coupled to a trailer, the tractor protection valve should be placed in the ______ position.

A

normal

46
Q

46) How should you test the trailer connection for security?

A

Pull gently forward with the trailer brakes locked, then look at it carefully

47
Q

47) The trailer air supply valve should automatically close when air pressure falls to what range?

A

20-45 PSI

48
Q

48) What part of the kingpin should the jaws be locked around?

A

The shank

49
Q

49) The higher your center of gravity of your truck, the:

A

easier it is to turn over

50
Q

50) When checking that the trailer is securely coupled to the tractor, the landing gear should be:

A

slightly raised

51
Q

51) If you must back your trailer on a curved path, you should position your vehicle so you can back:

A

to the driver’s side

52
Q

52) If your ASB is not working on your trailer, you should:

A

drive normally, but get the system serviced soon

53
Q

53) Compared to a straight truck or bus, there are ____ things to inspect on a combination vehicle.

A

More

54
Q

54) Air lines are often colored. The emergency line is? The service line is?

A

Red, blue.

55
Q

55) To stop a trailer skid you should:

A

release the service brake

56
Q

56) What gear should the transmission be in after you have uncoupled and are inspecting the trailer supports?

A

neutral

57
Q

57) You have coupled to a trailer. Where should the landing gear be before driving away?

A

Fully raised with the crank handle secured in the bracket

CDL Answers (3 decks)

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