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VA · GK (Class A) Endorsement

Virginia Combination Vehicles CDL Practice Test

Below are 25 exam-style questions for the Virginia Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Virginia Department of Motor Vehicles. Try to answer each question on your own before reading the answer key directly under it. The questions and answer choices are shuffled deterministically per state and endorsement, so the order will stay the same on repeat visits — that lets you genuinely measure your improvement.

Heads up: this is a study tool, not a graded exam. Cover the answer with your hand or a sheet of paper for an honest practice run, then re-read the explanations for any questions you missed. Aim for 22 out of 25 or better, three times in a row, before scheduling the real exam.
Question 1 of 25
A safe combination-vehicle following distance is at least:
  • A One second per 10 feet of vehicle length below 40 mph, plus one extra second above 40 mph
  • B A vehicle length
  • C No specific rule
  • D Two car lengths
Correct answer: A
A 60-ft combination needs at least 6 seconds under 40 mph, 7 seconds above 40 mph.
Question 2 of 25
When the trailer brakes are operating but pulling weakly, this can indicate:
  • A Driver fatigue
  • B Air leakage in the supply line, low pressure, or a brake-balance issue
  • C Cargo placement
  • D Engine wear
Correct answer: B
Weak trailer brakes are usually an air-system problem and require diagnosis before continuing.
Question 3 of 25
Most rear-end collisions caused by combination vehicles result from:
  • A Driving too fast for conditions and/or too closely
  • B Worn out tires
  • C Cargo movement
  • D Engine failure
Correct answer: A
Speed and following distance dominate the causes. Increase cushion and slow down.
Question 4 of 25
A converter dolly:
  • A Is part of the tractor
  • B Is used only when triple-towing
  • C Is used to convert a semitrailer into a full trailer for towing in combination
  • D Replaces the fifth wheel on the tractor
Correct answer: C
A converter dolly turns a semitrailer into a full trailer that can be coupled behind another trailer.
Question 5 of 25
You should never back under a trailer that is:
  • A Too high — it can damage the kingpin or skip over the fifth wheel
  • B Loaded
  • C Properly chocked
  • D Empty
Correct answer: A
A trailer set too high can skip over the fifth-wheel jaws and not lock, or damage the coupling.
Question 6 of 25
When you turn a combination vehicle right at an intersection, you should:
  • A Swing wide to the right first to avoid hitting the curb
  • B Stop in the middle of the turn
  • C Keep the cab close to the curb and swing the front out so following cars cannot squeeze beside you on the right
  • D Swing left then right
Correct answer: C
Hugging the right side of the turn lane prevents another vehicle from squeezing in next to you and getting clipped by the trailer.
Question 7 of 25
After coupling, the locking jaws should:
  • A Be closed around the shank of the kingpin (not on the head)
  • B Be loose
  • C Be missing
  • D Be open
Correct answer: A
Visual check: jaws around the shank, not the head. A flashlight helps.
Question 8 of 25
The "emergency" line (supply line) on a tractor-trailer:
  • A Drains the wet tank
  • B Sends supply air to the trailer reservoirs and controls the trailer emergency brakes
  • C Operates the parking brake only
  • D Carries electrical signals
Correct answer: B
Loss of pressure on the emergency line causes the trailer's emergency brake to apply automatically.
Question 9 of 25
When uncoupling, after the tractor is clear, you should:
  • A Disable the trailer parking brake
  • B Move the tractor far away immediately without checking
  • C Check that the trailer is stable on its landing gear
  • D Connect the lines back to the tractor
Correct answer: C
Verify the trailer is sitting solidly before leaving the area.
Question 10 of 25
When you cross a railroad track in a combination vehicle, the safest practice is:
  • A Cross in a low gear without shifting
  • B Shift in the middle of the track
  • C Honk and accelerate
  • D Stop on the tracks if traffic ahead slows
Correct answer: A
Cross in a low gear without shifting; never stop on the tracks; never shift in the middle.
Question 11 of 25
A "trailer skid" usually starts because:
  • A The fifth wheel breaks
  • B The trailer brakes lock up
  • C The tractor brakes lock up
  • D A wheel bearing fails
Correct answer: B
Locking the trailer brakes is the most common cause of a trailer skid (jackknife).
Question 12 of 25
Trailer air supply valves on tractors are typically:
  • A Triangular, green, marked SERVICE
  • B Square, white, marked CHARGE
  • C Octagonal, red, marked TRAILER AIR SUPPLY
  • D Round, blue, marked TRACTOR
Correct answer: C
The trailer air-supply valve is the red, octagonal knob — a federal standard.
Question 13 of 25
The proper test of a good fifth-wheel coupling is:
  • A Honk the horn
  • B Look at the locking jaws only
  • C Listen for a click
  • D Tug the trailer with the trailer parking brakes set
Correct answer: D
After coupling and locking, gently pull forward against the locked trailer brakes to confirm engagement.
Question 14 of 25
When a tractor pulls a trailer with brakes that are out of balance:
  • A No effect on safety
  • B Stopping distances are normal
  • C Stopping distances increase and the trailer can swing
  • D Steering becomes easier
Correct answer: C
Brake imbalance makes the rig pull, lengthens stopping distance, and increases the chance of trailer swing.
Question 15 of 25
Brake-system pressure should be checked:
  • A Every 3 hours
  • B Only at the start of the day
  • C Before, during, and after coupling
  • D Only at the destination
Correct answer: C
Pressure changes during coupling indicate connection problems early.
Question 16 of 25
Off-tracking means:
  • A Sliding sideways
  • B The trailer wheels follow a tighter arc than the tractor wheels in a turn
  • C Driving off the road
  • D Loss of traction
Correct answer: B
In a right turn, the trailer wheels cut the corner. To compensate, the tractor must swing wider.
Question 17 of 25
When backing into a dock, you should:
  • A GOAL — Get Out And Look — and walk around the trailer first
  • B Back at full speed
  • C Have the dispatcher in the cab
  • D Use only mirrors
Correct answer: A
A walk-around catches obstacles, people, and overhead clearance issues before you back.
Question 18 of 25
Which of the following can damage a fifth wheel?
  • A All of the above
  • B Coupling with the trailer too high
  • C Backing too fast
  • D Failure to grease
Correct answer: A
All three: high trailer skips the jaws, fast backing impacts hardware, and lack of lubrication accelerates wear.
Question 19 of 25
Sharp turns at low speed will cause:
  • A Wheel damage
  • B Brake fade
  • C No off-tracking
  • D Off-tracking — the trailer wheels follow a tighter arc than the tractor
Correct answer: D
Off-tracking always happens; sharper turns make it worse.
Question 20 of 25
When inspecting the air lines between tractor and trailer, look for:
  • A Cargo placement
  • B Engine oil leaks
  • C Cuts, abrasions, and worn seals
  • D Loose lug nuts only
Correct answer: C
Air-line condition is a typical roadside inspection focus on combinations.
Question 21 of 25
The trailer hand valve should NOT be used to:
  • A Apply trailer brakes momentarily
  • B Test the trailer brakes
  • C Both for parking and to prevent jackknife
  • D Hold the vehicle when parking
Correct answer: C
Don't use it to park (it can leak off) or to prevent a jackknife (it locks the trailer wheels and worsens the skid).
Question 22 of 25
Which is true about coupling order to a trailer?
  • A Connect electrical first, then air
  • B Connect only air; electrical is optional
  • C Connect air emergency line first, then service line, then electrical (or per company policy) — verify with brake check
  • D Connect any line first; order doesn't matter
Correct answer: C
Specific orders vary by carrier, but the principle is to charge the trailer brakes before moving and to verify with a brake check.
Question 23 of 25
A combination vehicle with empty trailers:
  • A Stops faster than when loaded
  • B May actually take longer to stop because brakes are designed for the loaded weight
  • C Stops in the same distance
  • D Stops only with parking brake
Correct answer: B
Empty trailers can lock up easily and skid, which counterintuitively increases stopping distance.
Question 24 of 25
Trailer wheels with worn brake linings:
  • A Only need attention every 5 years
  • B Make the truck quieter
  • C Are normal until the lining is gone
  • D Should be replaced when worn beyond manufacturer specs
Correct answer: D
Worn linings are an out-of-service item; replace per manufacturer/federal limits.
Question 25 of 25
When you uncouple a trailer with cargo on it, you should:
  • A Leave the gear up
  • B Use blocks instead
  • C Raise the gear partway
  • D Lower the landing gear all the way until firmly on the ground, then a few extra cranks
Correct answer: D
Make sure the gear takes the full weight before pulling out from under.

Study tips for the Virginia Combination Vehicles exam

The Combination Vehicles portion of the Virginia CDL exam is graded out of the bank of questions the Virginia Department of Motor Vehicles draws from each year. While the exact bank is not published, every question is sourced from the Combination Vehicles chapter of the Virginia CDL handbook, which itself is derived from the FMCSA Model Commercial Driver's License Manual. That means studying our practice tests, reading the corresponding handbook chapter, and re-reading the parts you got wrong is genuinely the most efficient route to a first-time pass.

Most successful applicants follow a simple cycle: take the practice test cold, write down every question you missed, open the matching chapter of the official Virginia handbook, re-read the section that contains the right answer, then re-take the practice test 24 to 48 hours later. The 24-hour delay matters — sleep is when your brain commits new information to long-term memory, and CDL knowledge questions reward that kind of consolidated learning rather than cramming.

Pay particular attention to questions that include qualifier words like always, never, only, primary, or most. CDL test writers love to flip the right answer with a single qualifier. When two answer choices look almost identical, pay attention to the verb (is it must, should, or may?) and to any numbers (14 days, 100 air miles, 8 hours, 70/8 split). On endorsement tests in particular, watch for trick framing where a true statement about a different endorsement is offered as the "correct" answer to a question that is actually about Combination Vehicles.

Test-day logistics matter too. Bring photo ID, your Social Security card or birth certificate, your medical examiner's certificate (DOT card), and proof of state residency if you haven't already submitted those documents. The Virginia Department of Motor Vehicles will not let you sit for the knowledge exam without your documentation, and most offices charge an additional fee for re-attempts. Arrive early — the wait at most CDL testing offices runs 30 to 60 minutes — and silence your phone before the exam begins.

Finally, keep your General Knowledge fundamentals sharp even when you're focused on the Combination Vehicles exam. Many states administer multiple knowledge tests in a single sitting, and questions on weight definitions (GVWR, GCWR, GAWR), stopping distance, and the pre-trip inspection routine show up across endorsements. If you're unsure on the basics, sit a fresh Virginia General Knowledge practice test before scheduling the real exam.

Next steps

Missed more than four questions? Re-read the Combination Vehicles study guide and the matching chapter in the official Virginia CDL handbook. Then come back and re-take the test. Once you can score 22 of 25 or higher on three runs in a row, you're in good shape to schedule the real exam at your local Virginia Department of Motor Vehicles office.

Already comfortable with this endorsement? Drill another: VA General Knowledge · VA Air Brakes · VA Hazardous Materials · VA Passenger · VA School Bus · VA Tank Vehicle · VA Doubles / Triples

New to the CDL process in Virginia? Read How to apply for a CDL in Virginia for the document checklist and step-by-step timeline.