CDL COMBINATION 2026 EXAMINATION SET QUESTIONS
AND SOLUTIONS RATED A+
✔✔Check for normal air pressure, release the parking & emergency brakes, move the
vehicle forward slowly, and apply trailer brake with the trailer hand valve, if so equipped.
This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes
c. How you can test the trailer service brakes - ✔✔c. How you can test the trailer
service brakes
✔✔Check for normal air pressure, release the parking & emergency brakes, move the
vehicle forward at 3-5 mph, then push in the foot brake and clutch. This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes
c. How you can test the trailer service brakes
d. How you can test the service brakes - ✔✔d. How you can test the service brakes
✔✔Check for normal air pressure, release the parking brake but leave the trailer
emergency brake out, pull gently against the brakes in low gear. This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes Correct
c. How you can test the trailer service brakes
d. How you can test the service brakes - ✔✔b. How you can test the emergency brakes
✔✔Check for normal air pressure, release the trailer emergency brake but leave the
tractor parking brake out, pull gently against the brakes in low gear. This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes
c. How you can test the trailer service brakes
d. How you can test the service brakes
Feedback - ✔✔a. How you can test the tractor parking brakes
✔✔Combination vehicles and the rearward amplification each trailer has after a quick
lane change is referred to as what?
a. Crack the road effect
b. Crack the whip effect
c. The trailer effect - ✔✔b. Crack the whip effect
,✔✔Combination vehicles are usually heavier, longer and require more driving skill than
single commercial vehicles.
a. True
b. False - ✔✔a. True
✔✔Compared to a straight truck or bus, there are _____ things to inspect on
combination vehicles.
a. Fewer
b. More
c. The same number
d. All of the above - ✔✔b. More
✔✔Describe what the service line is for.
a. It carries air which is controlled by the foot brake
b. It carries air which is controlled by the trailer handvalve
c. Both answers are correct
d. None of the above - ✔✔c. Both answers are correct
✔✔Fully loaded rigs are 10 times more likely to roll over in a crash than empty rigs.
a. True
b. Fals - ✔✔a. True
✔✔If one of the glad hands on your blue air line is missing a seal _____.
a. Take one off the red air line and use that as a temporary replacement
b. You might end up with a service line air leak
c. You might end up with an emergency line air leak
d. It's not a major problem and you should continue coupling - ✔✔b. You might end up
with a service line air leak
✔✔If the brakes are not released when you pushed the trailer air supply valve, you
should:
a. Cross the air lines
b. Check the electrical cable
c. Rev up your engine to increase rpm's
d. Check air line connection - ✔✔d. Check air line connection
✔✔If the emergency line comes apart while you are driving a combination vehicle, but
the service line stays together, what will happen right away?
, a. The trailer's tank will exhaust through the open line.
b. The emergency trailer brakes will come on.
c. The tractor parking brakes will come on.
d. Nothing will happen until you try to apply the brakes. - ✔✔. The emergency trailer
brakes will come on.
✔✔If the locking jaws will not release while uncoupling, what should you do?
a. Release parking brakes and gently back up with trailer brakes locked to ease the
tension.
b. Release parking brakes and gently back up with trailer brakes off to ease the tension.
c. Leave parking brakes on and gently back up with trailer brakes locked to ease the
tension.
d. Leave parking brakes on and gently back up with trailer brakes off to ease the
tension. - ✔✔a. Release parking brakes and gently back up with trailer brakes locked to
ease the tension.
✔✔If the service line comes apart while you are driving a combination vehicle, but the
emergency line stays together, what will happen right away?
a. The trailer's tank will exhaust through the open line.
b. The emergency trailer brakes will come on.
c. The tractor parking brakes will come on.
d. Nothing will happen until you try to apply the brakes. - ✔✔d. Nothing will happen until
you try to apply the brakes.
✔✔If you cross connect the two air hoses, the following will result:
a. Nothing, the air lines are interchangeable
b. You will not have air to release your trailer emergency brakes.
c. Your tractor brakes will lock up.
d. You could not move the tractor. - ✔✔b. You will not have air to release your trailer
emergency brakes.
✔✔If your glad hands on your tractor are not color coded, how can you determine which
one is the emergency line?
a. Hook them both up and hope for the best.
b. Push in your trailer supply knob and listen for the sound of escaping air from the glad
hand to find out which one is the emergency line.
c. Hook them both up, release the brakes, drive forward fast, and slam on the brakes.
d. There is no way to tell which is which if they are not color coded. - ✔✔b. Push in your
trailer supply knob and listen for the sound of escaping air from the glad hand to find out
which one is the emergency line.
AND SOLUTIONS RATED A+
✔✔Check for normal air pressure, release the parking & emergency brakes, move the
vehicle forward slowly, and apply trailer brake with the trailer hand valve, if so equipped.
This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes
c. How you can test the trailer service brakes - ✔✔c. How you can test the trailer
service brakes
✔✔Check for normal air pressure, release the parking & emergency brakes, move the
vehicle forward at 3-5 mph, then push in the foot brake and clutch. This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes
c. How you can test the trailer service brakes
d. How you can test the service brakes - ✔✔d. How you can test the service brakes
✔✔Check for normal air pressure, release the parking brake but leave the trailer
emergency brake out, pull gently against the brakes in low gear. This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes Correct
c. How you can test the trailer service brakes
d. How you can test the service brakes - ✔✔b. How you can test the emergency brakes
✔✔Check for normal air pressure, release the trailer emergency brake but leave the
tractor parking brake out, pull gently against the brakes in low gear. This best describes:
a. How you can test the tractor parking brakes
b. How you can test the emergency brakes
c. How you can test the trailer service brakes
d. How you can test the service brakes
Feedback - ✔✔a. How you can test the tractor parking brakes
✔✔Combination vehicles and the rearward amplification each trailer has after a quick
lane change is referred to as what?
a. Crack the road effect
b. Crack the whip effect
c. The trailer effect - ✔✔b. Crack the whip effect
,✔✔Combination vehicles are usually heavier, longer and require more driving skill than
single commercial vehicles.
a. True
b. False - ✔✔a. True
✔✔Compared to a straight truck or bus, there are _____ things to inspect on
combination vehicles.
a. Fewer
b. More
c. The same number
d. All of the above - ✔✔b. More
✔✔Describe what the service line is for.
a. It carries air which is controlled by the foot brake
b. It carries air which is controlled by the trailer handvalve
c. Both answers are correct
d. None of the above - ✔✔c. Both answers are correct
✔✔Fully loaded rigs are 10 times more likely to roll over in a crash than empty rigs.
a. True
b. Fals - ✔✔a. True
✔✔If one of the glad hands on your blue air line is missing a seal _____.
a. Take one off the red air line and use that as a temporary replacement
b. You might end up with a service line air leak
c. You might end up with an emergency line air leak
d. It's not a major problem and you should continue coupling - ✔✔b. You might end up
with a service line air leak
✔✔If the brakes are not released when you pushed the trailer air supply valve, you
should:
a. Cross the air lines
b. Check the electrical cable
c. Rev up your engine to increase rpm's
d. Check air line connection - ✔✔d. Check air line connection
✔✔If the emergency line comes apart while you are driving a combination vehicle, but
the service line stays together, what will happen right away?
, a. The trailer's tank will exhaust through the open line.
b. The emergency trailer brakes will come on.
c. The tractor parking brakes will come on.
d. Nothing will happen until you try to apply the brakes. - ✔✔. The emergency trailer
brakes will come on.
✔✔If the locking jaws will not release while uncoupling, what should you do?
a. Release parking brakes and gently back up with trailer brakes locked to ease the
tension.
b. Release parking brakes and gently back up with trailer brakes off to ease the tension.
c. Leave parking brakes on and gently back up with trailer brakes locked to ease the
tension.
d. Leave parking brakes on and gently back up with trailer brakes off to ease the
tension. - ✔✔a. Release parking brakes and gently back up with trailer brakes locked to
ease the tension.
✔✔If the service line comes apart while you are driving a combination vehicle, but the
emergency line stays together, what will happen right away?
a. The trailer's tank will exhaust through the open line.
b. The emergency trailer brakes will come on.
c. The tractor parking brakes will come on.
d. Nothing will happen until you try to apply the brakes. - ✔✔d. Nothing will happen until
you try to apply the brakes.
✔✔If you cross connect the two air hoses, the following will result:
a. Nothing, the air lines are interchangeable
b. You will not have air to release your trailer emergency brakes.
c. Your tractor brakes will lock up.
d. You could not move the tractor. - ✔✔b. You will not have air to release your trailer
emergency brakes.
✔✔If your glad hands on your tractor are not color coded, how can you determine which
one is the emergency line?
a. Hook them both up and hope for the best.
b. Push in your trailer supply knob and listen for the sound of escaping air from the glad
hand to find out which one is the emergency line.
c. Hook them both up, release the brakes, drive forward fast, and slam on the brakes.
d. There is no way to tell which is which if they are not color coded. - ✔✔b. Push in your
trailer supply knob and listen for the sound of escaping air from the glad hand to find out
which one is the emergency line.
