25 realistic Combination Vehicles practice questions for Georgia CDL applicants. Required for: Class A CDL (tractor-trailer combinations). Official test: 20 questions, 16 correct to pass.
Question 1 of 25 · Emergency Equipment
What are some common causes of vehicle fires?
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A.
Under-inflated tires and electrical short circuits
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B.
Improper use of flares
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C.
Cargo that catches fire from spilled fuel
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D.
All of the above
Correct answer: D.
All of these can cause vehicle fires. Pre-trip and en-route inspections reduce risk.
Question 2 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 3 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 4 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.
Question 5 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 6 of 25 · Backing
Which is correct about backing a tractor-trailer?
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A.
Steer in the same direction you want the trailer to go
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B.
Steer in the opposite direction you want the trailer to go
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C.
Use the throttle to back
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D.
Back as fast as possible
Correct answer: B.
When backing, turn the steering wheel opposite to the direction you want the trailer to move.
Question 7 of 25 · Skids
What should you do to recover from a trailer skid?
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A.
Apply more brake pressure
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B.
Release the brakes to allow trailer wheels to roll again
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C.
Steer hard right
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D.
Accelerate forward
Correct answer: B.
Release brakes to let trailer wheels roll, then steer to recover direction.
Question 8 of 25 · Vehicle Dynamics
Off-tracking is most pronounced in:
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A.
Single vehicles
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B.
Long combinations and curves
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C.
Empty trailers
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D.
Vehicles with disc brakes
Correct answer: B.
Longer wheelbases and tighter curves cause greater off-tracking.
Question 9 of 25 · Operation
Which of these is most important when driving with a trailer?
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A.
Use the engine retarder constantly
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B.
Use proper braking and signaling
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C.
Drive at maximum speed limits
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D.
Skip pre-trip checks if running late
Correct answer: B.
Proper braking and clear signaling are essential to safe combination driving.
Question 10 of 25 · Coupling
What is the fifth wheel?
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A.
A spare wheel
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B.
A coupling device that connects the tractor to the trailer
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C.
A device on the trailer to support cargo
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D.
A type of axle
Correct answer: B.
The fifth wheel is the round, plate-shaped coupling that connects the tractor to the trailer.
Question 11 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 12 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 13 of 25 · Vehicle Dynamics
Which of these is true about the front trailer of a doubles or triples?
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A.
It is less likely to overturn
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B.
It is more stable
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C.
It is more likely to overturn than the rear trailer
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D.
It does not need brakes
Correct answer: A.
The front trailer in a combination is generally more stable than the rear trailer.
Question 14 of 25 · Coupling
What is the proper position for the fifth wheel?
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A.
Tilted down toward the rear of the tractor with jaws open
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B.
Pointed straight up
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C.
Locked and ready
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D.
Removed for inspection
Correct answer: A.
Before coupling, the fifth wheel should tilt down toward the rear with the jaws open.
Question 15 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 16 of 25 · Coupling
What should you do before connecting air lines?
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A.
Clean the rubber seals on the glad hands
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B.
Lubricate them with oil
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C.
Replace the seals every trip
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D.
Heat them up
Correct answer: A.
Clean glad hand seals before connecting to ensure a good air seal.
Question 17 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 18 of 25 · Skids
How can drivers avoid jackknifing?
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A.
Brake gently and look ahead
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B.
Adjust speed for road and weather
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C.
Use ABS where equipped
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D.
All of the above
Correct answer: D.
Smooth braking, appropriate speed, and ABS all reduce jackknife risk.
Question 19 of 25 · Combination Air
What should the tractor protection valve do?
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A.
Keep tractor air supply if trailer breaks away or develops a major leak
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B.
Set the trailer parking brake on a hill
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C.
Apply trailer brakes during a normal stop
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D.
Disconnect the trailer
Correct answer: A.
It protects the tractor air supply by closing if a major air loss occurs.
Question 20 of 25 · Skids
How can you correct a tractor jackknife?
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A.
Apply the brakes harder
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B.
Steer in the direction of the skid and accelerate gently
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C.
Stop steering input
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D.
Release the brakes and counter-steer
Correct answer: D.
Release the brakes to regain traction; counter-steer carefully to recover.
Question 21 of 25 · Coupling
What does a "low coupling" condition look like?
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A.
Trailer is too high above the fifth wheel
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B.
Trailer is at the right height
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C.
Trailer is too low and tractor frame can hit the trailer
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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 · Skids
What can cause a trailer skid in a combination vehicle?
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A.
Locked trailer wheels and over-application of brakes
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B.
Light loads on the trailer
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C.
Tight steering at low speed
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D.
High pressure in steering tires
Correct answer: A.
Locked trailer wheels cause trailer skid; reduce brake pressure to recover.
Question 23 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 24 of 25 · Combination Air
Trailer brakes are required to be:
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A.
Adjusted properly and matched to tractor brakes
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B.
Stronger than tractor brakes
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C.
Disengaged on level roads
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D.
Off when empty
Correct answer: A.
Trailer brakes must be in proper adjustment and balance with tractor brakes.
Question 25 of 25 · Skids
What is "tractor jackknife"?
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A.
Tractor drive wheels skid and the trailer pushes the tractor sideways
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B.
Trailer wheels skid
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C.
Steering wheels skid
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D.
Engine fails
Correct answer: A.
When drive wheels skid, the trailer can push the tractor sideways into a jackknife.
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 Georgia Department of Driver Services administers this knowledge test as part of its commercial driver license program. To earn the Combination Vehicles on your Georgia CDL, you need to score at least 16 out of 20 on the official version.
Topics covered on this practice test
- Skids: 6 questions
- Vehicle Dynamics: 4 questions
- Coupling: 4 questions
- Inspection: 3 questions
- Combination Air: 3 questions
- Emergency Equipment: 1 question
- CDL Rules: 1 question
- Backing: 1 question
- Operation: 1 question
- Cargo: 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 Georgia 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.