NC CDL COMBINATION VEHICLES EXAM SCRIPT 2025
QUESTIONS WITH ANSWERS GUARANTEE A+
✔✔You should not back a tractor under a trailer until the whole air system is: - ✔✔At
normal pressure.
✔✔Which part of the kingpin should the locking jaws close around? - ✔✔The shank.
✔✔When you get ready to back under the semi-trailer you should line up: - ✔✔Directly
in front of the trailer.
✔✔How should you test the tractor semi-trailer connection for security? - ✔✔Pull gently
forward in low gear against the locked trailer brakes, then look at it carefully.
✔✔When should you use the hand valve to park a combination vehicle? - ✔✔Never.
✔✔You supply air to the trailer tanks by: - ✔✔Pushing in the trailer air supply valve.
✔✔Why should you be sure that the fifth wheel plate is greased as required? - ✔✔To
prevent steering problems.
✔✔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 brake sounds.
✔✔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 slowly around turns.
✔✔Before you back under a trailer, make sure the: - ✔✔Trailer brakes are locked.
✔✔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? - ✔✔Nothing is likely to
happen until you try to apply the brakes.
✔✔The air leakage rate for a combination vehicle (engine off, brakes on) should not be
more than ___ PSI per minute. - ✔✔4
✔✔In normal driving, some drivers use the hand valve before applying the brake pedal
to prevent a jackknife. Which of these statements is true? - ✔✔If the trailer has not
spring brakes, you can drive away, but you will not have trailer brakes.
✔✔Why should you lock the tractor glad hands (or dummy couplers) to each other when
you are not towing a trailer? - ✔✔It will keep dirt and water out of the lines.
, ✔✔For coupling to be completed, the safety catch for the fifth wheel locking lever must
be: - ✔✔Over the locking lever.
✔✔The front trailer supports are up and trailer is resting on the tractor. Make sure: -
✔✔There is enough clearance between the tractor frame and the landing gear.
✔✔You have a major leak in the service line and you put on the brakes. Service air
pressure will escape and cause the: - ✔✔Trailer emergency brakes to come on.
✔✔When backing under a tractor under a trailer you should expect: - ✔✔Trailer will be
lifted slightly when the tractor backs under it.
✔✔The driver crosses the air lines when hooking up to an old trailer. What will happen?
- ✔✔If the trailer has no spring brakes, you can drive away, but you will not have trailer
brakes.
✔✔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 the semi-trailer? - ✔✔The emergency
and service air lines.
✔✔Air lines on a combination vehicle are often colored to keep them from getting mixed
up. The emergency line is ____; the service line is ____. - ✔✔Red, blue
✔✔Which of these statements is true? - ✔✔"Bobtail" tractors can take longer to stop
than a combination vehicle loaded to the maximum gross weight.
✔✔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.
✔✔The hand valve should be used: - ✔✔To test the trailer brakes.
✔✔The air leakage rate for a combination vehicle (engine off, brakes off) should be no
more than ___ PSI per minute. - ✔✔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
vehicle.
✔✔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: - ✔✔The tractor
protection valve to close.
QUESTIONS WITH ANSWERS GUARANTEE A+
✔✔You should not back a tractor under a trailer until the whole air system is: - ✔✔At
normal pressure.
✔✔Which part of the kingpin should the locking jaws close around? - ✔✔The shank.
✔✔When you get ready to back under the semi-trailer you should line up: - ✔✔Directly
in front of the trailer.
✔✔How should you test the tractor semi-trailer connection for security? - ✔✔Pull gently
forward in low gear against the locked trailer brakes, then look at it carefully.
✔✔When should you use the hand valve to park a combination vehicle? - ✔✔Never.
✔✔You supply air to the trailer tanks by: - ✔✔Pushing in the trailer air supply valve.
✔✔Why should you be sure that the fifth wheel plate is greased as required? - ✔✔To
prevent steering problems.
✔✔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 brake sounds.
✔✔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 slowly around turns.
✔✔Before you back under a trailer, make sure the: - ✔✔Trailer brakes are locked.
✔✔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? - ✔✔Nothing is likely to
happen until you try to apply the brakes.
✔✔The air leakage rate for a combination vehicle (engine off, brakes on) should not be
more than ___ PSI per minute. - ✔✔4
✔✔In normal driving, some drivers use the hand valve before applying the brake pedal
to prevent a jackknife. Which of these statements is true? - ✔✔If the trailer has not
spring brakes, you can drive away, but you will not have trailer brakes.
✔✔Why should you lock the tractor glad hands (or dummy couplers) to each other when
you are not towing a trailer? - ✔✔It will keep dirt and water out of the lines.
, ✔✔For coupling to be completed, the safety catch for the fifth wheel locking lever must
be: - ✔✔Over the locking lever.
✔✔The front trailer supports are up and trailer is resting on the tractor. Make sure: -
✔✔There is enough clearance between the tractor frame and the landing gear.
✔✔You have a major leak in the service line and you put on the brakes. Service air
pressure will escape and cause the: - ✔✔Trailer emergency brakes to come on.
✔✔When backing under a tractor under a trailer you should expect: - ✔✔Trailer will be
lifted slightly when the tractor backs under it.
✔✔The driver crosses the air lines when hooking up to an old trailer. What will happen?
- ✔✔If the trailer has no spring brakes, you can drive away, but you will not have trailer
brakes.
✔✔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 the semi-trailer? - ✔✔The emergency
and service air lines.
✔✔Air lines on a combination vehicle are often colored to keep them from getting mixed
up. The emergency line is ____; the service line is ____. - ✔✔Red, blue
✔✔Which of these statements is true? - ✔✔"Bobtail" tractors can take longer to stop
than a combination vehicle loaded to the maximum gross weight.
✔✔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.
✔✔The hand valve should be used: - ✔✔To test the trailer brakes.
✔✔The air leakage rate for a combination vehicle (engine off, brakes off) should be no
more than ___ PSI per minute. - ✔✔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
vehicle.
✔✔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: - ✔✔The tractor
protection valve to close.
