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Combinations vehicles
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  • 問題数 66 • 8/21/2024

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    問題一覧

  • 1

    When backing a tractor under a trailer you should

    always use the lowest reverse gear

  • 2

    After the trailer has been coupled to the tractor, the tractor protection control valve should be placed in what position?

    Normal

  • 3

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

    The coupling is not right and should be fixed before driving the coupled unit

  • 4

    Off-tracking or cheating causes of which of these to follow the wider pass while making a turn?

    Tractor towing a 45 feet trailer

  • 5

    The air lines on a combination vehicles are often colored to prevent them from mixing up. The emergency line is ______, the service line is ______.

    red, blue

  • 6

    The semitrailer made before 1975 that are equipped with the air brakes:

    often do not have spring brakes

  • 7

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

    4

  • 8

    Compared to a straight truck or bus there are _____ things to inspect in a combination vehicle.

    More

  • 9

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

    trailer emergency brakes to come on

  • 10

    A tractor with a ____ trailer requires the shortest amount of stopping distance.

    fully loaded

  • 11

    When you get ready to back under a semitrailer you should line up:

    directly in front of the trailer

  • 12

    Off-tracking or cheating causes of which of these to follow the wider pass while making a turn?

    tractor towing a 45 feet trailer

  • 13

    To unlock the fifth wheel the locking lever should be placed in the _____ position.

    open

  • 14

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

    emergency

  • 15

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

    tilted down toward the end of the trailer

  • 16

    What gear should the tractor engine be in after you uncouple the trailer and are inspecting the trailer supports?

    neutral

  • 17

    You have coupled with a semitrailer. Where should you put the iron trailer supports before driving away?

    fully raised the cranck handle secured in its bracket

  • 18

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

    over the locking lever

  • 19

    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 :

    applying and releasing the trailer brakes and listening for the sound of the brake

  • 20

    Before you back under a trailer, make sure that:

    the trailer brakes are locked

  • 21

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

    make firm contact with the ground, then crackle hits a low gear a few extra turns

  • 22

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

    if the trailer has no spring brakes, you could drive away but you wouldn’t have trailer brakes

  • 23

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

    go slow around turns

  • 24

    To stop a trailer skid you should:

    release the service brakes

  • 25

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

    to prevent steering problems

  • 26

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

    emergency trailer brakes to come on

  • 27

    When connecting the glad hands press the two seals with the couple together at what degree to each other?

    90 degrees

  • 28

    Which of these statements is true?

    bobtail tractors can take longer to stop than a combination vehicle loaded to maximum gross weight

  • 29

    After you have coupled the trailer you should have to raise the landing gear by using:

    low gear

  • 30

    You supply air to the trailer tanks by:

    pushing in the trailer air supply valve

  • 31

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

    the shank

  • 32

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

    nothing

  • 33

    You have pushed the trailer air supply valve. You should not back a tractor under a trailer until the whole air system is:

    at normal pressure

  • 34

    You are coupling tractor to a semitrailer. You have connected the airlines. Before backing under the trailer you should:

    supply air to the trailer system, then pull out the air supply knob

  • 35

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

    3

  • 36

    The safest way to make a turn without entering another traffic lane is:

    you should turn wide as you complete the turn

  • 37

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

    easier to turn over

  • 38

    A driver crosses the air line when hooking up to an old trailer. What will happen?

    if the trailer has no spring brakes, you could drive away but you wouldn’t have the trailer brakes

  • 39

    The hand valve should be used

    to test the trailer brakes

  • 40

    When driving a set of doubles it is necessary to close which shut off valve in the last trailer.

    back

  • 41

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

    nothing is likely to happen until you try to apply the brakes

  • 42

    There are two things that a driver can do to prevent a rollover. They are (1) go slow around turns ; (2):

    keep the cargo we close to the ground as possible

  • 43

    After connecting the air lines but before backing under the trailer you should

    supply air to the trailer system, then pull out the air supply knob

  • 44

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

    the emergency and service air lines

  • 45

    Why should you lock the tractor glad hands to each other ( or dummy couplers) when you are not towing a trailer ?

    it will keep dirt or water out of the lines

  • 46

    While driving behind other vehicle under good condition you should allow at least one second between your vehicle and the vehicle ahead for each _____ (how many) feet of your vehicle length?

    10

  • 47

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

    nothing is likely to happen until you try the brakes

  • 48

    Glad hands are usually connecting which of these?

    service and emergency air lines from the vehicle to the trailer

  • 49

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

    trailer will be lifted slightly when the tractor backs under it

  • 50

    While checking if the trailer is securely coupled to the trailer the landing gears should be

    slightly raised

  • 51

    Air and electrical lines from the tractor to the trailer should be:

    secured but with enough loop to turn

  • 52

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

    at normal pressure

  • 53

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

    pulling the tractor ahead gently with the trailer brakes locked

  • 54

    Where should the tractor be when you inspect landing gear uncoupling the trailer?

    with the tractor frame under the trailer

  • 55

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

    emergency trailer brakes to come on

  • 56

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

    Both a and b are correct

  • 57

    When uncoupling the trailer, after you shut off the trailer air supply and lock the trailer brakes, you should:

    back up gently to ease pressure on the fifth wheel

  • 58

    Air brake equipped trailers made before 1975:

    often do not have spring brakes

  • 59

    The iron trailers supports are up and the trailer is resting on the tractor. Make sure:

    there is enough clearance between the tractor frame and the landing gear

  • 60

    If you cannot make a turn without entering another traffic lane:

    you should turn wide as you complete the turn

  • 61

    When checking the trailer emergency brakes the tractor protection control valve should be placed in what position?

    emergency

  • 62

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

    the tractor protection valve to close

  • 63

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

    it should not be done

  • 64

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

    never

  • 65

    If the brakes are not released when you pushed the trailer air supply valve you should:

    check air line connection

  • 66

    How should you test the tractor-semitrailer connection for security?

    pull gently forward in low gear against the locked trailer brakes then look at it carefully