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GA · GK (Class A) Endorsement

Georgia Combination Vehicles CDL Practice Test

Below are 25 exam-style questions for the Georgia Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Georgia Department of Driver Services. 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
The trailer hand valve operates:
  • A The parking brake
  • B Both tractor and trailer brakes simultaneously
  • C The tractor service brakes only
  • D The trailer service brakes only
Correct answer: D
The hand valve applies only the trailer service brakes. It is for testing — not for parking or routine use.
Question 2 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 Two car lengths
  • C No specific rule
  • D A vehicle length
Correct answer: A
A 60-ft combination needs at least 6 seconds under 40 mph, 7 seconds above 40 mph.
Question 3 of 25
Trailer ABS uses:
  • A Sensors at each wheel that release brake pressure when wheel lockup is detected
  • B Hydraulic brakes
  • C Hand valves
  • D A separate compressor
Correct answer: A
Wheel-speed sensors trigger valves to release pressure when lockup is detected.
Question 4 of 25
When coupling a tractor to a semitrailer, the trailer should be at:
  • A Whatever height it happens to be
  • B A height where the tractor will lift the trailer slightly when backing under
  • C A height that requires the tractor to drop down to fit
  • D Maximum legal height
Correct answer: B
The trailer should be slightly lower than the fifth wheel so backing in lifts the trailer.
Question 5 of 25
Which of the following can damage a fifth wheel?
  • A All of the above
  • B Failure to grease
  • C Coupling with the trailer too high
  • D Backing too fast
Correct answer: A
All three: high trailer skips the jaws, fast backing impacts hardware, and lack of lubrication accelerates wear.
Question 6 of 25
After coupling, the locking jaws should:
  • A Be open
  • B Be missing
  • C Be closed around the shank of the kingpin (not on the head)
  • D Be loose
Correct answer: C
Visual check: jaws around the shank, not the head. A flashlight helps.
Question 7 of 25
A combination vehicle with empty trailers:
  • A Stops only with parking brake
  • B Stops in the same distance
  • C May actually take longer to stop because brakes are designed for the loaded weight
  • D Stops faster than when loaded
Correct answer: C
Empty trailers can lock up easily and skid, which counterintuitively increases stopping distance.
Question 8 of 25
The "emergency" line (supply line) on a tractor-trailer:
  • A Carries electrical signals
  • B Sends supply air to the trailer reservoirs and controls the trailer emergency brakes
  • C Drains the wet tank
  • D Operates the parking brake only
Correct answer: B
Loss of pressure on the emergency line causes the trailer's emergency brake to apply automatically.
Question 9 of 25
Which is true about coupling order to a trailer?
  • A Connect air emergency line first, then service line, then electrical (or per company policy) — verify with brake check
  • B Connect electrical first, then air
  • C Connect only air; electrical is optional
  • D Connect any line first; order doesn't matter
Correct answer: A
Specific orders vary by carrier, but the principle is to charge the trailer brakes before moving and to verify with a brake check.
Question 10 of 25
When uncoupling, after the tractor is clear, you should:
  • A Connect the lines back to the tractor
  • B Disable the trailer parking brake
  • C Move the tractor far away immediately without checking
  • D Check that the trailer is stable on its landing gear
Correct answer: D
Verify the trailer is sitting solidly before leaving the area.
Question 11 of 25
A tractor jackknife happens when:
  • A The tractor parking brake fails
  • B The drive wheels lose traction and the tractor begins to slide
  • C The trailer is too heavy
  • D The fifth wheel disengages
Correct answer: B
A drive-wheel skid causes the tractor to swing into the trailer at an angle.
Question 12 of 25
Brake-system pressure should be checked:
  • A Only at the start of the day
  • B Before, during, and after coupling
  • C Only at the destination
  • D Every 3 hours
Correct answer: B
Pressure changes during coupling indicate connection problems early.
Question 13 of 25
Why should you not jackknife to get out of a tight spot?
  • A It is fine if you are careful
  • B It is illegal in some states
  • C It is the standard procedure
  • D It can damage the cab and the trailer (cab corner crush)
Correct answer: D
Bending the tractor too sharply against the trailer can cause body damage and disconnect the lines.
Question 14 of 25
The seven-pin connector on a tractor-trailer carries:
  • A Electrical power for trailer lights and ABS
  • B Fuel
  • C Air for the brakes
  • D Hydraulic fluid
Correct answer: A
The seven-pin (or older five-pin) is electrical, supplying lights, brake-light signal, and ABS.
Question 15 of 25
If you cross the air lines (service to emergency and vice versa) when coupling:
  • A Nothing will happen
  • B You will notice immediately because trailer brakes will not work properly
  • C The horn will sound
  • D The trailer brakes will be locked on
Correct answer: B
Crossed glad hands often produce no air flow to brake chambers and incorrect brake operation; you should notice on the brake test.
Question 16 of 25
The proper sequence for uncoupling is generally:
  • A No specific order is required
  • B Lower landing gear, disconnect lines, release fifth wheel, pull tractor away
  • C Release fifth wheel first, then connect lines
  • D Pull tractor away first, then disconnect lines
Correct answer: B
Lower the landing gear, chock the wheels, disconnect air and electrical lines and stow them, release the fifth wheel, then slowly pull the tractor forward.
Question 17 of 25
The trailer hand valve should NOT be used to:
  • A Test the trailer brakes
  • B Apply trailer brakes momentarily
  • C Hold the vehicle when parking
  • D Both for parking and to prevent jackknife
Correct answer: D
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 18 of 25
If you are pulling two trailers, the heavier trailer should be:
  • A Last
  • B Either position is fine
  • C First (closest to the tractor)
  • D Loaded last
Correct answer: C
Heavier trailer first reduces the rear-trailer crack-the-whip effect.
Question 19 of 25
A converter dolly:
  • A Is used to convert a semitrailer into a full trailer for towing in combination
  • B Is used only when triple-towing
  • C Is part of the tractor
  • D Replaces the fifth wheel on the tractor
Correct answer: A
A converter dolly turns a semitrailer into a full trailer that can be coupled behind another trailer.
Question 20 of 25
Glad hands are:
  • A Coupling devices for connecting tractor air lines to the trailer
  • B Brake adjustment levers
  • C Manual transmission shifters
  • D Electrical connectors
Correct answer: A
Glad hands have rubber seals and a metal coupler that joins the tractor and trailer air lines.
Question 21 of 25
Sharp turns at low speed will cause:
  • A Brake fade
  • B Wheel damage
  • 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 22 of 25
When backing into a dock, you should:
  • A Use only mirrors
  • B Have the dispatcher in the cab
  • C Back at full speed
  • D GOAL — Get Out And Look — and walk around the trailer first
Correct answer: D
A walk-around catches obstacles, people, and overhead clearance issues before you back.
Question 23 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 24 of 25
The trailer landing gear (dolly legs) should be:
  • A Disconnected before driving
  • B Always halfway extended
  • C Lowered to the ground while driving
  • D Fully raised before driving
Correct answer: D
Landing gear must be fully raised and the crank handle secured before moving the trailer.
Question 25 of 25
Most tire problems on a combination vehicle:
  • A Need a mechanic to find
  • B Show up only at high speed
  • C Are caused by low fuel
  • D Can be detected during pre-trip inspection by visual and pressure checks
Correct answer: D
Visual and pressure checks catch most problems before they become roadside failures.

Study tips for the Georgia Combination Vehicles exam

The Combination Vehicles portion of the Georgia CDL exam is graded out of the bank of questions the Georgia Department of Driver Services draws from each year. While the exact bank is not published, every question is sourced from the Combination Vehicles chapter of the Georgia 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 Georgia 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 Georgia Department of Driver Services 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 Georgia 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 Georgia 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 Georgia Department of Driver Services office.

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

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