25 realistic Combination Vehicles practice questions for Connecticut CDL applicants. Required for: Class A CDL (tractor-trailer combinations). Official test: 20 questions, 16 correct to pass.
Question 1 of 25 · Vehicle Dynamics
Which of these is true about the front trailer of a doubles or triples?
-
A.
It is less likely to overturn
-
B.
It is more stable
-
C.
It is more likely to overturn than the rear trailer
-
D.
It does not need brakes
Correct answer: A.
The front trailer in a combination is generally more stable than the rear trailer.
Question 2 of 25 · Coupling
When uncoupling, you should:
-
A.
Lower the landing gear before pulling the kingpin release
-
B.
Lift the trailer with the fifth wheel
-
C.
Release the parking brake
-
D.
Rev the engine
Correct answer: A.
Lower the landing gear so the trailer is supported before disconnecting the kingpin.
Question 3 of 25 · Inspection
What is the proper way to test the parking brakes after coupling?
-
A.
Apply trailer parking brake and try to gently pull forward
-
B.
Drive at normal speed
-
C.
Apply foot brake repeatedly
-
D.
Disconnect glad hands
Correct answer: A.
A gentle pull forward with parking brakes set confirms holding power.
Question 4 of 25 · Cargo
Why is securement of cargo essential?
-
A.
To prevent the load from shifting
-
B.
To prevent injury to others
-
C.
To prevent damage to the vehicle
-
D.
All of the above
Correct answer: D.
Securement protects the load, prevents shifts that affect handling, and protects others.
Question 5 of 25 · Skids
What should you do to recover from a trailer skid?
-
A.
Apply more brake pressure
-
B.
Release the brakes to allow trailer wheels to roll again
-
C.
Steer hard right
-
D.
Accelerate forward
Correct answer: B.
Release brakes to let trailer wheels roll, then steer to recover direction.
Question 6 of 25 · Vehicle Dynamics
Off-tracking is most pronounced in:
-
A.
Single vehicles
-
B.
Long combinations and curves
-
C.
Empty trailers
-
D.
Vehicles with disc brakes
Correct answer: B.
Longer wheelbases and tighter curves cause greater off-tracking.
Question 7 of 25 · Coupling
How can you keep a stiff coupling system from causing problems?
-
A.
Lubricate the fifth wheel
-
B.
Avoid backing under fast
-
C.
Inspect mounting bolts
-
D.
All of the above
Correct answer: D.
Lubricate, back slowly, and inspect mounting bolts to keep the coupling working safely.
Question 8 of 25 · Coupling
Which is true about pulling away after coupling?
-
A.
Test that the kingpin is locked by gently pulling forward against the trailer brakes
-
B.
Pull away as quickly as possible
-
C.
Lower the landing gear before pulling away
-
D.
Disconnect the air lines first
Correct answer: A.
A pull-test confirms the kingpin is locked before driving away.
Question 9 of 25 · Speed Management
What is the most common cause of fatal crashes for combination vehicles?
-
A.
Loss of control due to speed too fast for conditions
-
B.
Engine failure
-
C.
Tire blowouts
-
D.
Mechanical defects only
Correct answer: A.
Driving too fast for conditions is the leading cause of serious crashes.
Question 10 of 25 · Following Distance
What is "rear-end collision" risk for combination vehicles?
-
A.
It is reduced when carrying long cargo
-
B.
They have a higher risk because of long stopping distances and rear blind spots
-
C.
They have no greater risk
-
D.
Only for empty rigs
Correct answer: B.
Long stopping distance and rear blind spots increase rear-end collision risk.
Question 11 of 25 · Vehicle Dynamics
Empty trucks have what kind of stopping distance compared to fully loaded ones?
-
A.
Shorter
-
B.
Same
-
C.
Longer
-
D.
Half
Correct answer: C.
Empty rigs have less traction on drive axles and require greater stopping distance.
Question 12 of 25 · Coupling
What should you do before connecting air lines?
-
A.
Clean the rubber seals on the glad hands
-
B.
Lubricate them with oil
-
C.
Replace the seals every trip
-
D.
Heat them up
Correct answer: A.
Clean glad hand seals before connecting to ensure a good air seal.
Question 13 of 25 · Cargo
How do you know the trailer is properly loaded?
-
A.
Cargo is centered, balanced, and properly secured
-
B.
Cargo extends beyond the trailer ends
-
C.
Cargo is stacked unevenly
-
D.
Cargo is on top of the cab
Correct answer: A.
Centered, balanced, and secured loads handle predictably.
Question 14 of 25 · Vehicle Dynamics
What is "off-tracking"?
-
A.
When the rear wheels follow a different path than the front wheels
-
B.
When the trailer slides off the road
-
C.
When the trailer is improperly loaded
-
D.
A type of fifth wheel
Correct answer: A.
In turns, rear wheels travel a smaller arc than the front, causing off-tracking.
Question 15 of 25 · Skids
How can you correct a tractor jackknife?
-
A.
Apply the brakes harder
-
B.
Steer in the direction of the skid and accelerate gently
-
C.
Stop steering input
-
D.
Release the brakes and counter-steer
Correct answer: D.
Release the brakes to regain traction; counter-steer carefully to recover.
Question 16 of 25 · Skids
What can cause a trailer skid in a combination vehicle?
-
A.
Locked trailer wheels and over-application of brakes
-
B.
Light loads on the trailer
-
C.
Tight steering at low speed
-
D.
High pressure in steering tires
Correct answer: A.
Locked trailer wheels cause trailer skid; reduce brake pressure to recover.
Question 17 of 25 · Coupling
When you finish coupling, the air lines should be:
-
A.
Connected to the proper glad hands and supported off the catwalk and the deck plate
-
B.
Coiled tightly on top of the trailer
-
C.
Loose so they can move freely
-
D.
Disconnected
Correct answer: A.
Air lines must be connected and supported off the deck so they don't snag or wear.
Question 18 of 25 · Coupling
You should NEVER:
-
A.
Back under a trailer at an angle
-
B.
Inspect the fifth wheel
-
C.
Use the parking brake
-
D.
Tug-test the kingpin
Correct answer: A.
Backing at an angle can damage the kingpin or push the trailer sideways.
Question 19 of 25 · Coupling
What is the kingpin?
-
A.
A pin in the engine
-
B.
A vertical pin on the front of the trailer that locks into the fifth wheel
-
C.
A part of the air brake system
-
D.
A type of warning device
Correct answer: B.
The kingpin slides into the fifth wheel jaws to lock the trailer to the tractor.
Question 20 of 25 · Inspection
When should you check trailer brakes during operation?
-
A.
First few miles after coupling
-
B.
Every fuel stop
-
C.
Just at the end of the trip
-
D.
Never during the trip
Correct answer: A.
Test trailer brakes early in the trip to make sure they are functioning correctly.
Question 21 of 25 · Coupling
What does a "low coupling" condition look like?
-
A.
Trailer is too high above the fifth wheel
-
B.
Trailer is at the right height
-
C.
Trailer is too low and tractor frame can hit the trailer
-
D.
Trailer is angled to the right
Correct answer: C.
A trailer too low can damage the tractor frame as it slides under it.
Question 22 of 25 · Combination Air
Trailer brakes are required to be:
-
A.
Adjusted properly and matched to tractor brakes
-
B.
Stronger than tractor brakes
-
C.
Disengaged on level roads
-
D.
Off when empty
Correct answer: A.
Trailer brakes must be in proper adjustment and balance with tractor brakes.
Question 23 of 25 · Combination Air
When the trailer breaks away or loses air pressure, the trailer brakes should:
-
A.
Release
-
B.
Apply automatically
-
C.
Vibrate
-
D.
Disengage
Correct answer: B.
A loss of air should automatically apply the trailer brakes via the emergency system.
Question 24 of 25 · CDL Rules
Which is true about long combination vehicles (LCVs)?
-
A.
They are easier to maneuver in tight spaces
-
B.
They require additional driver training and special permits
-
C.
They handle the same as single trailers
-
D.
They never require special routes
Correct answer: B.
LCVs need extra training, certifications, and often follow restricted routes.
Question 25 of 25 · Coupling
What are landing gear used for?
-
A.
Supporting the front of the trailer when uncoupled
-
B.
Steering the trailer
-
C.
Powering the trailer brakes
-
D.
Lighting the trailer
Correct answer: A.
Landing gear holds up the trailer when it is not connected to a tractor.
About the Combination Vehicles Test
The Combination Vehicles test covers driving combination vehicles safely, combination vehicle air brakes, antilock brake systems, coupling and uncoupling, and inspecting a combination vehicle. Combination vehicles are usually heavier, longer, and require more driving skill than single commercial vehicles. They are also more likely to roll over and jackknife.
The Connecticut Department of Motor Vehicles administers this knowledge test as part of its commercial driver license program. To earn the Combination Vehicles on your Connecticut CDL, you need to score at least 16 out of 20 on the official version.
Topics covered on this practice test
- Coupling: 9 questions
- Vehicle Dynamics: 4 questions
- Skids: 3 questions
- Inspection: 2 questions
- Cargo: 2 questions
- Combination Air: 2 questions
- Speed Management: 1 question
- Following Distance: 1 question
- CDL Rules: 1 question
How to use this practice test
- Read each question carefully. CDL questions are written precisely — small wording differences matter.
- Click "Show Answers & Explanations" only after answering every question. Don't peek mid-test.
- Read the explanation for every question, even ones you got right. The reasoning is more important than the answer.
- Repeat the test until you score 100%. The questions are deterministic per state, so you can track your improvement over multiple sessions.
- Move on to the other endorsement tests for Connecticut until you're ready for the official exam.
Tips specific to the Combination Vehicles test
Combination Vehicles questions cover off-tracking, jackknifing, coupling and uncoupling, the fifth wheel, kingpin, glad hands, landing gear, and the special air-brake considerations for tractor-trailer combinations. Expect detailed step-by-step coupling questions.