Cdl Combinations

Front 1

When you get ready to back under the semi trailer you should line up:

Back 1

ANSWER: Directly in front of the trailer

Front 2

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:

Back 2

Applying and releasing the trailer brakes and listening for brake sounds

Front 3

The air leakage rate for a combination vehicle (engine off, brakes on) should not be more than ____ PSI per minute.

Back 3

ANSWER: 4

Front 4

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

Back 4

ANSWER: Never

Front 5

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

Back 5

ANSWER: It should not be done

Front 6

The air leakage rate for a combination vehicle (engine off, brakes off) should be no more than ____ PSI per minute.

Back 6

ANSWER: 3

Front 7

Which answer is correct for the air valves when testing the trailer service brakes only?

Back 7

ANSWER: Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolly: released

Front 8

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

Back 8

ANSWER: It will be raised slightly when the tractor is backed under it

Front 9

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

Back 9

ANSWER: Trailer emergency / spring brakes to come on

Front 10

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

Back 10

ANSWER:There is enough clearance between the tops of the tractor tires and the nose of the trailer
There is enough clearance between the tractor frame and the landing gear
Both of the answers are correct

Front 11

Before you back under a trailer, make sure the:

Back 11

ANSWER: Trailer brakes are locked

Front 12

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

Back 12

ANSWER: It will be raised slightly when the tractor is backed under it

Front 13

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

Back 13

ANSWER: The shank

Front 14

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

Back 14

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

Front 15

The air leakage rate for a combination vehicle (engine off, brakes off) should be no more than ____ PSI per minute.

Back 15

ANSWER: 3

Front 16

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

Back 16

ANSWER: To prevent steering problems

Front 17

The hand valve should be used:

Back 17

ANSWER: To test the trailer brakes

Front 18

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

Back 18

ANSWER: Over the locking lever

Front 19

When backing your tractor under a trailer, you should expect:

Back 19

ANSWER: Trailer will be lifted slightly when the tractor backs under it

Front 20

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

Back 20

ANSWER: None

Front 21

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

Back 21

ANSWER: At normal pressure

Front 22

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?

Back 22

ANSWER: The emergency and service air lines

Front 23

You have coupled with a semi trailer. In what position should you put the front trailer supports before driving away?

Back 23

ANSWER: Fully raised with the crank handle secured in its bracket

Front 24

You supply air to the trailer tanks by:

Back 24

ANSWER: Pushing in the trailer air supply valve

Front 25

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:

Back 25

ANSWER: The tractor protection valve to close

Front 26

At what degrees do you hold your air line glad hands when connecting them?

Back 26

ANSWER: 90 degrees

Front 27

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):

Back 27

ANSWER: Go slowly around turns

Front 28

Semi trailers made before 1975 that are equipped with air brakes:

Back 28

ANSWER: Often do not have spring brakes

Front 29

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

Back 29

ANSWER: If the trailer has no spring brakes, you can drive away, but you will not have trailer brakes

Front 30

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:

Back 30

ANSWER: Applying and releasing the trailer brakes and listening for brake sounds

Front 31

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?

Back 31

ANSWER: Nothing is likely to happen until you try to apply the brakes

Front 32

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

Back 32

ANSWER: Pull gently forward in low gear against the locked trailer brakes, then look at it carefully

Front 33

Which of these statements is true?

Back 33

1.Always delay braking a heavy vehicle until you have no other choice
2.Light vehicles need more braking power to stop than heavy ones
3."Bobtail" tractors can take longer to stop than a combination vehicle loaded to the maximum gross weight

Front 34

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

Back 34

ANSWER: It will keep dirt and water out of the lines

Front 35

Which answer is correct for the air valves when testing the trailer spring / parking brakes only?

Back 35

ANSWER: Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolly: released

Front 36

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

Back 36

ANSWER: Supply air to the trailer system, then pull out the air supply knob to lock the trailer brakes

Front 37

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

Back 37

There is enough clearance between the tops of the tractor tires and the nose of the trailer
There is enough clearance between the tractor frame and the landing gear
Both of the answers are correct

Front 38

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

Back 38

ANSWER: Red, blue

Front 39

Which answer is correct for the air valves when testing the trailer service brakes only?

Back 39

ANSWER: Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolly: released

Front 40

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

Back 40

ANSWER: Emergency trailer brakes to come on