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CT · GK (Class A) Endorsement

Connecticut Combination Vehicles CDL Practice Test

Below are 25 exam-style questions for the Connecticut Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Connecticut 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
When the trailer brakes are operating but pulling weakly, this can indicate:
  • A Driver fatigue
  • B Cargo placement
  • C Air leakage in the supply line, low pressure, or a brake-balance issue
  • D Engine wear
Correct answer: C
Weak trailer brakes are usually an air-system problem and require diagnosis before continuing.
Question 2 of 25
If you are pulling two trailers, the heavier trailer should be:
  • A Last
  • B First (closest to the tractor)
  • C Loaded last
  • D Either position is fine
Correct answer: B
Heavier trailer first reduces the rear-trailer crack-the-whip effect.
Question 3 of 25
The proper test of a good fifth-wheel coupling is:
  • A Look at the locking jaws only
  • B Honk the horn
  • 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 4 of 25
A tractor jackknife happens when:
  • A The drive wheels lose traction and the tractor begins to slide
  • B The trailer is too heavy
  • C The fifth wheel disengages
  • D The tractor parking brake fails
Correct answer: A
A drive-wheel skid causes the tractor to swing into the trailer at an angle.
Question 5 of 25
When a tractor pulls a trailer with brakes that are out of balance:
  • A Stopping distances increase and the trailer can swing
  • B Stopping distances are normal
  • C Steering becomes easier
  • D No effect on safety
Correct answer: A
Brake imbalance makes the rig pull, lengthens stopping distance, and increases the chance of trailer swing.
Question 6 of 25
The "emergency" line (supply line) on a tractor-trailer:
  • A Sends supply air to the trailer reservoirs and controls the trailer emergency brakes
  • B Carries electrical signals
  • C Operates the parking brake only
  • D Drains the wet tank
Correct answer: A
Loss of pressure on the emergency line causes the trailer's emergency brake to apply automatically.
Question 7 of 25
Before pulling the kingpin release lever to uncouple, you must:
  • A Disconnect the electrical line first
  • B Lower the trailer landing gear and chock the trailer wheels
  • C Drain the air tanks
  • D Honk the horn
Correct answer: B
Always lower the landing gear and chock the trailer so it cannot move once you pull out from under it.
Question 8 of 25
A worn or damaged fifth wheel can cause:
  • A Engine damage
  • B Tire wear only
  • C Rust on the cab
  • D The trailer to come uncoupled
Correct answer: D
Worn locking jaws or a cracked structure can fail and release the trailer in motion.
Question 9 of 25
When uncoupling, after the tractor is clear, you should:
  • A Move the tractor far away immediately without checking
  • B Connect the lines back to the tractor
  • C Check that the trailer is stable on its landing gear
  • D Disable the trailer parking brake
Correct answer: C
Verify the trailer is sitting solidly before leaving the area.
Question 10 of 25
During a brake check before moving, you should look for:
  • A Steering wander only
  • B Smoke from the cab
  • C Engine knocking
  • D Pulling, sticking, or unusual feel as you apply the brakes
Correct answer: D
Low-speed brake test identifies pulling, sticking, or weakness so you don't discover it on the highway.
Question 11 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 Replaces the fifth wheel on the tractor
  • D Is part of the tractor
Correct answer: A
A converter dolly turns a semitrailer into a full trailer that can be coupled behind another trailer.
Question 12 of 25
Which is true about combination braking?
  • A Drive wheels never lock
  • B ABS prevents jackknife in all cases
  • C Trailer wheels lock more often than drive wheels in panic stops
  • D Brake balance is irrelevant
Correct answer: C
Empty trailer wheels lock easily and contribute to jackknife and trailer-swing risks.
Question 13 of 25
When parking a tractor-trailer, you should:
  • A Leave the engine running with the brakes off
  • B Set both tractor and trailer parking brakes
  • C Set only the tractor parking brake
  • D Use the trailer hand valve
Correct answer: B
For full parking, both parking brakes apply.
Question 14 of 25
Glad hands are:
  • A Manual transmission shifters
  • B Brake adjustment levers
  • C Electrical connectors
  • D Coupling devices for connecting tractor air lines to the trailer
Correct answer: D
Glad hands have rubber seals and a metal coupler that joins the tractor and trailer air lines.
Question 15 of 25
You should never back under a trailer that is:
  • A Empty
  • B Loaded
  • C Too high — it can damage the kingpin or skip over the fifth wheel
  • D Properly chocked
Correct answer: C
A trailer set too high can skip over the fifth-wheel jaws and not lock, or damage the coupling.
Question 16 of 25
When you cross a railroad track in a combination vehicle, the safest practice is:
  • A Honk and accelerate
  • B Cross in a low gear without shifting
  • C Shift in the middle of the track
  • D Stop on the tracks if traffic ahead slows
Correct answer: B
Cross in a low gear without shifting; never stop on the tracks; never shift in the middle.
Question 17 of 25
When backing a tractor-trailer, you should:
  • A Back as fast as practical
  • B Always back to the right
  • C Back without using mirrors
  • D Back to the left whenever possible because you can see better
Correct answer: D
Backing to the driver's side gives the best view of the trailer. Always GOAL — Get Out And Look — before and during.
Question 18 of 25
Trailer ABS uses:
  • A Hand valves
  • B A separate compressor
  • C Sensors at each wheel that release brake pressure when wheel lockup is detected
  • D Hydraulic brakes
Correct answer: C
Wheel-speed sensors trigger valves to release pressure when lockup is detected.
Question 19 of 25
The fifth-wheel locking lever should be:
  • A Released and visible after coupling
  • B Removed before driving
  • C Tied with rope
  • D Locked and the safety latch in place after coupling
Correct answer: D
After backing under, the locking jaws must close around the kingpin and the safety latch must be in place.
Question 20 of 25
When you turn a combination vehicle right at an intersection, you should:
  • A Swing left then right
  • B Keep the cab close to the curb and swing the front out so following cars cannot squeeze beside you on the right
  • C Stop in the middle of the turn
  • D Swing wide to the right first to avoid hitting the curb
Correct answer: B
Hugging the right side of the turn lane prevents another vehicle from squeezing in next to you and getting clipped by the trailer.
Question 21 of 25
When you uncouple a trailer with cargo on it, you should:
  • A Use blocks instead
  • B Lower the landing gear all the way until firmly on the ground, then a few extra cranks
  • C Raise the gear partway
  • D Leave the gear up
Correct answer: B
Make sure the gear takes the full weight before pulling out from under.
Question 22 of 25
Combination vehicles are usually harder to drive than single CMVs because:
  • A They take more skill to back, couple, and uncouple
  • B They are heavier and longer
  • C All of the above
  • D They have a higher rollover risk
Correct answer: C
All three factors apply. The Combination Vehicles section of the federal manual emphasizes the higher skill needed.
Question 23 of 25
Brake-system pressure should be checked:
  • A Only at the destination
  • B Before, during, and after coupling
  • C Every 3 hours
  • D Only at the start of the day
Correct answer: B
Pressure changes during coupling indicate connection problems early.
Question 24 of 25
A heavy combination vehicle in a curve is most likely to:
  • A Stop suddenly
  • B Spin out
  • C Lose engine power
  • D Roll over before sliding
Correct answer: D
Loaded trailers reach the rollover threshold before they slide. Slow before the curve.
Question 25 of 25
The proper sequence for uncoupling is generally:
  • A Release fifth wheel first, then connect lines
  • B Pull tractor away first, then disconnect lines
  • C Lower landing gear, disconnect lines, release fifth wheel, pull tractor away
  • D No specific order is required
Correct answer: C
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.

Study tips for the Connecticut Combination Vehicles exam

The Combination Vehicles portion of the Connecticut CDL exam is graded out of the bank of questions the Connecticut 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 Connecticut 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 Connecticut 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 Connecticut 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 Connecticut 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 Connecticut 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 Connecticut Department of Motor Vehicles office.

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

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