NC CDL COMBINATION VEHICLES
EXAM QUESTIONS AND CORRECT
ANSWERS. VERIFIED 2025/2026.
You are coupling a semi-trailer to your tractor but have not yet backed under, the trailer is at the
right height when: - ANS It will be raised slightly when the tractor is backed under it.
You should not back a tractor under a trailer until the whole air system is: - ANS At normal
pressure.
Which part of the kingpin should the locking jaws close around? - ANS The shank.
When you get ready to back under the semi-trailer you should line up: - ANS Directly in front
of the trailer.
How should you test the tractor semi-trailer connection for security? - ANS 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? - ANS Never.
You supply air to the trailer tanks by: - ANS Pushing in the trailer air supply valve.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Why should you be sure that the fifth wheel plate is greased as required? - ANS 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: - ANS 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): - ANS Go slowly around turns.
Before you back under a trailer, make sure the: - ANS 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? - ANS 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. - ANS 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? - ANS 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? - ANS 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: -
ANS Over the locking lever.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
EXAM QUESTIONS AND CORRECT
ANSWERS. VERIFIED 2025/2026.
You are coupling a semi-trailer to your tractor but have not yet backed under, the trailer is at the
right height when: - ANS It will be raised slightly when the tractor is backed under it.
You should not back a tractor under a trailer until the whole air system is: - ANS At normal
pressure.
Which part of the kingpin should the locking jaws close around? - ANS The shank.
When you get ready to back under the semi-trailer you should line up: - ANS Directly in front
of the trailer.
How should you test the tractor semi-trailer connection for security? - ANS 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? - ANS Never.
You supply air to the trailer tanks by: - ANS Pushing in the trailer air supply valve.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Why should you be sure that the fifth wheel plate is greased as required? - ANS 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: - ANS 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): - ANS Go slowly around turns.
Before you back under a trailer, make sure the: - ANS 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? - ANS 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. - ANS 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? - ANS 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? - ANS 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: -
ANS Over the locking lever.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
