25 realistic Combination Vehicles practice questions for West Virginia CDL applicants. Required for: Class A CDL (tractor-trailer combinations). Official test: 20 questions, 16 correct to pass.
Question 1 of 25 · Inspection
Which of these is not a part of the trailer's electrical system?
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A.
Lights
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B.
Brake control
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C.
Power line cord (pigtail)
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D.
Hydraulic pump
Correct answer: D.
Hydraulic pumps are not part of standard trailer electrical systems on highway combinations.
Question 2 of 25 · Speed Management
What is the most common cause of fatal crashes for combination vehicles?
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A.
Loss of control due to speed too fast for conditions
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B.
Engine failure
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C.
Tire blowouts
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D.
Mechanical defects only
Correct answer: A.
Driving too fast for conditions is the leading cause of serious crashes.
Question 3 of 25 · Inspection
When checking the trailer air supply, you should:
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A.
Charge the trailer with air, then disconnect the supply hose to test trailer emergency brakes
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B.
Pump the brakes
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C.
Disconnect the trailer power cord
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D.
Open the trailer service line manually
Correct answer: A.
Disconnecting the supply line tests that the trailer emergency brakes apply automatically.
Question 4 of 25 · Inspection
When inspecting your trailer's wheels, what should you look for?
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A.
Loose or missing nuts
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B.
Cracked or broken wheel rims
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C.
Bent or broken studs
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D.
All of the above
Correct answer: D.
Inspect for loose nuts, cracks, bent studs, and other defects on every pre-trip.
Question 5 of 25 · Coupling
How can you keep a stiff coupling system from causing problems?
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A.
Lubricate the fifth wheel
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B.
Avoid backing under fast
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C.
Inspect mounting bolts
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D.
All of the above
Correct answer: D.
Lubricate, back slowly, and inspect mounting bolts to keep the coupling working safely.
Question 6 of 25 · Combination Air
When the trailer breaks away or loses air pressure, the trailer brakes should:
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A.
Release
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B.
Apply automatically
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C.
Vibrate
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D.
Disengage
Correct answer: B.
A loss of air should automatically apply the trailer brakes via the emergency system.
Question 7 of 25 · Cargo
Why is securement of cargo essential?
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A.
To prevent the load from shifting
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B.
To prevent injury to others
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C.
To prevent damage to the vehicle
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D.
All of the above
Correct answer: D.
Securement protects the load, prevents shifts that affect handling, and protects others.
Question 8 of 25 · Cargo
What can cause a high center of gravity?
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A.
Loading cargo too low
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B.
Loading cargo too high or unevenly
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C.
Driving too slowly
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D.
Empty trailers
Correct answer: B.
Stacking cargo too high or loading unevenly raises the center of gravity and rollover risk.
Question 9 of 25 · Bobtail
What happens if you bobtail (no trailer) and brake hard?
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A.
You stop more quickly than loaded
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B.
Drive wheels can lock and skid because there is little weight on them
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C.
Vehicle handles like a loaded truck
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D.
No special concerns
Correct answer: B.
Bobtailing leaves little weight on drive axles, increasing skid risk under hard braking.
Question 10 of 25 · Mountain Driving
When should you use lower gears?
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A.
On steep upgrades and downgrades
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B.
In flat terrain
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C.
In stop-and-go traffic only
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D.
Never in a combination vehicle
Correct answer: A.
Use lower gears on grades to maintain torque and engine braking.
Question 11 of 25 · CDL Rules
Which is true about long combination vehicles (LCVs)?
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A.
They are easier to maneuver in tight spaces
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B.
They require additional driver training and special permits
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C.
They handle the same as single trailers
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D.
They never require special routes
Correct answer: B.
LCVs need extra training, certifications, and often follow restricted routes.
Question 12 of 25 · Skids
What is the result of a "trailer jackknife"?
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A.
Trailer continues straight ahead
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B.
Trailer swings out and tractor pivots
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C.
Trailer comes to a quick safe stop
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D.
Trailer disengages
Correct answer: B.
In a trailer jackknife, the trailer swings out, often into adjacent lanes.
Question 13 of 25 · Skids
Which is the most common cause of trailer skid?
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A.
Driving too fast for conditions
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B.
Locking the rear trailer wheels by overbraking
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C.
Worn brake shoes
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D.
Too much trailer weight
Correct answer: B.
Trailer skids most often occur when rear trailer wheels lock during braking.
Question 14 of 25 · Vehicle Dynamics
When you turn suddenly with a high center of gravity, the trailer can:
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A.
Roll over
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B.
Stop more quickly
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C.
Track better
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D.
Reduce fuel use
Correct answer: A.
High centers of gravity make trailers prone to rollover during sharp turns.
Question 15 of 25 · Vehicle Dynamics
What's the safest way to handle a tight turn with a long combination?
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A.
Take it wide using both lanes if necessary
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B.
Drive as fast as possible to maintain momentum
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C.
Use the trailer hand valve
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D.
Make a tight turn
Correct answer: A.
Take wider turns to avoid hitting curbs or other vehicles due to off-tracking.
Question 16 of 25 · Coupling
When coupling, what should you do after the fifth wheel locks onto the kingpin?
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A.
Pull the tractor forward gently to make sure the kingpin is locked
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B.
Disconnect the air lines
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C.
Drive away immediately
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D.
Release the trailer parking brake first
Correct answer: A.
Tug-test by gently pulling forward with the trailer brakes set to confirm the lock.
Question 17 of 25 · Inspection
Which is true about gladhand seals?
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A.
They should be replaced if cracked or damaged
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B.
They never need replacement
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C.
They are the same as electrical connections
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D.
They are always made of metal
Correct answer: A.
Replace damaged or worn rubber seals to keep air from leaking at the gladhands.
Question 18 of 25 · Coupling
What is the kingpin?
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A.
A pin in the engine
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B.
A vertical pin on the front of the trailer that locks into the fifth wheel
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C.
A part of the air brake system
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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 19 of 25 · Vehicle Dynamics
Which of these is true about driving combination vehicles?
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A.
They are easier to handle than single vehicles
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B.
They are more likely to roll over and jackknife
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C.
They use less fuel per mile
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D.
They need fewer mirrors
Correct answer: B.
Combination vehicles require more skill and are more prone to rollovers and jackknives.
Question 20 of 25 · Cargo
How do you know the trailer is properly loaded?
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A.
Cargo is centered, balanced, and properly secured
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B.
Cargo extends beyond the trailer ends
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C.
Cargo is stacked unevenly
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D.
Cargo is on top of the cab
Correct answer: A.
Centered, balanced, and secured loads handle predictably.
Question 21 of 25 · Combination Air
Trailer hand valve is used to:
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A.
Test trailer brakes
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B.
Park the trailer
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C.
Bypass the foot valve
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D.
Drain trailer tanks
Correct answer: A.
Use the trailer hand valve only for testing — not for parking or normal stops.
Question 22 of 25 · Coupling
When you finish coupling, the air lines should be:
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A.
Connected to the proper glad hands and supported off the catwalk and the deck plate
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B.
Coiled tightly on top of the trailer
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C.
Loose so they can move freely
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D.
Disconnected
Correct answer: A.
Air lines must be connected and supported off the deck so they don't snag or wear.
Question 23 of 25 · Combination Air
What is glad hands?
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A.
Trailer doors
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B.
Couplers used to join air lines from the tractor to the trailer
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C.
Mirror brackets
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D.
Brake levers
Correct answer: B.
Glad hands connect the service and emergency air lines between tractor and trailer.
Question 24 of 25 · Following Distance
How can you reduce risk of rear-end collisions?
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A.
Maintain safe following distances and watch for slowing traffic
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B.
Drive at the speed limit always
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C.
Use mirrors only at night
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D.
Avoid signaling
Correct answer: A.
Use safe following distances and watch ahead so you have time to slow down.
Question 25 of 25 · Inspection
What is the proper way to test the parking brakes after coupling?
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A.
Apply trailer parking brake and try to gently pull forward
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B.
Drive at normal speed
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C.
Apply foot brake repeatedly
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D.
Disconnect glad hands
Correct answer: A.
A gentle pull forward with parking brakes set confirms holding power.
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 West Virginia Division of Motor Vehicles administers this knowledge test as part of its commercial driver license program. To earn the Combination Vehicles on your West Virginia CDL, you need to score at least 16 out of 20 on the official version.
Topics covered on this practice test
- Inspection: 5 questions
- Coupling: 4 questions
- Combination Air: 3 questions
- Cargo: 3 questions
- Vehicle Dynamics: 3 questions
- Skids: 2 questions
- Speed Management: 1 question
- Bobtail: 1 question
- Mountain Driving: 1 question
- CDL Rules: 1 question
- Following Distance: 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 West Virginia 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.