CDL COMBINATION VEHICLES QUESTIONS
WITH CORRECT ANSWERS 2025-2026
When should you use the hand valve to park a combination vehicle? - CORRECT ANSWER-
never
Which answer is correct for the air valves when testing the trailer service brakes only? -
CORRECT ANSWER-
Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolly: applied
You are coupling a semi trailer to your tractor but have not yet backed under. The trailer is
at the right height when: - CORRECT ANSWER-
It will be raised slightly when the tractor is backed under it.
How should you test the tractor trailer connection for security? - CORRECT ANSWER-
Pull gently forward in low gear against the locked trailer brakes, then inspect the coupling
Which answer is correct for the air valves when testing the trailer spring/parking brakes onl
y? - CORRECT ANSWER-
Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolly: released
Your emergency air line breaks or gets pulled apart while you are driving. The loss of press
ure will cause the: - CORRECT ANSWER-Emergency trailer brakes to come on
You supply air to the trailer tanks by: - CORRECT ANSWER-
Pushing in the trailer air supply valve.
There are two things that a driver can do to prevent a roll over. They are: (1) keep the carg
o as close to the ground as possible; and (2): - CORRECT ANSWER-Go slowly around turns.
, You are coupling a semi trailer to your tractor but have not yet backed under. The trailer is
at the right height when: - CORRECT ANSWER-
It will be raised slightly when the tractor is backed under it.
The fifth wheel locking lever is not locked after the jaws close around the kingpin; this mea
n: - CORRECT ANSWER-
The coupling is not right and should be fixed before driving the coupled unit
When backing your tractor under a trailer, you should expect: - CORRECT ANSWER-
Trailer will be lifted slightly when the tractor backs under it.
Before you start to uncouple, you must - CORRECT ANSWER-
Make sure the ground is solid and can support the weight of the trailer
During uncoupling, you should disconnect electrical cable and - CORRECT ANSWER-
Hang it with the plug down
As part of your vehicle in inspection test, if your vehicle is equipped with air brakes and ha
s a trailer, you will inspect the air connections between the truck or tractor and the trailer.
Make sure that the are locked in place and free of damage or air leaks. -
CORRECT ANSWER-Glad hands
If your vehicle gets stuck on a railroad track, you should - CORRECT ANSWER-
Get away from your vehicle and call 911 or the posted emergency number
If your test of the tractor protection valve is successful, - CORRECT ANSWER-
The tractor protection valve control (trailer air supply control) will pop out or go from "nor
mal" to "emergency"
WITH CORRECT ANSWERS 2025-2026
When should you use the hand valve to park a combination vehicle? - CORRECT ANSWER-
never
Which answer is correct for the air valves when testing the trailer service brakes only? -
CORRECT ANSWER-
Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolly: applied
You are coupling a semi trailer to your tractor but have not yet backed under. The trailer is
at the right height when: - CORRECT ANSWER-
It will be raised slightly when the tractor is backed under it.
How should you test the tractor trailer connection for security? - CORRECT ANSWER-
Pull gently forward in low gear against the locked trailer brakes, then inspect the coupling
Which answer is correct for the air valves when testing the trailer spring/parking brakes onl
y? - CORRECT ANSWER-
Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolly: released
Your emergency air line breaks or gets pulled apart while you are driving. The loss of press
ure will cause the: - CORRECT ANSWER-Emergency trailer brakes to come on
You supply air to the trailer tanks by: - CORRECT ANSWER-
Pushing in the trailer air supply valve.
There are two things that a driver can do to prevent a roll over. They are: (1) keep the carg
o as close to the ground as possible; and (2): - CORRECT ANSWER-Go slowly around turns.
, You are coupling a semi trailer to your tractor but have not yet backed under. The trailer is
at the right height when: - CORRECT ANSWER-
It will be raised slightly when the tractor is backed under it.
The fifth wheel locking lever is not locked after the jaws close around the kingpin; this mea
n: - CORRECT ANSWER-
The coupling is not right and should be fixed before driving the coupled unit
When backing your tractor under a trailer, you should expect: - CORRECT ANSWER-
Trailer will be lifted slightly when the tractor backs under it.
Before you start to uncouple, you must - CORRECT ANSWER-
Make sure the ground is solid and can support the weight of the trailer
During uncoupling, you should disconnect electrical cable and - CORRECT ANSWER-
Hang it with the plug down
As part of your vehicle in inspection test, if your vehicle is equipped with air brakes and ha
s a trailer, you will inspect the air connections between the truck or tractor and the trailer.
Make sure that the are locked in place and free of damage or air leaks. -
CORRECT ANSWER-Glad hands
If your vehicle gets stuck on a railroad track, you should - CORRECT ANSWER-
Get away from your vehicle and call 911 or the posted emergency number
If your test of the tractor protection valve is successful, - CORRECT ANSWER-
The tractor protection valve control (trailer air supply control) will pop out or go from "nor
mal" to "emergency"
