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MA · GK (Class A) Endorsement

Massachusetts Combination Vehicles CDL Practice Test

Below are 25 exam-style questions for the Massachusetts Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Massachusetts Registry 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 backing a trailer, small steering inputs cause:
  • A Loss of brake pressure
  • B Small trailer movement
  • C Large trailer angle changes; small inputs are key
  • D No effect
Correct answer: C
Trailer responds aggressively to small wheel inputs in reverse — back slowly and correct quickly.
Question 2 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 have a higher rollover risk
  • C All of the above
  • D They are heavier and longer
Correct answer: C
All three factors apply. The Combination Vehicles section of the federal manual emphasizes the higher skill needed.
Question 3 of 25
After coupling, the locking jaws should:
  • A Be loose
  • B Be open
  • C Be missing
  • D Be closed around the shank of the kingpin (not on the head)
Correct answer: D
Visual check: jaws around the shank, not the head. A flashlight helps.
Question 4 of 25
Glad hands are:
  • A Coupling devices for connecting tractor air lines to the trailer
  • B Electrical connectors
  • C Manual transmission shifters
  • D Brake adjustment levers
Correct answer: A
Glad hands have rubber seals and a metal coupler that joins the tractor and trailer air lines.
Question 5 of 25
The proper sequence for uncoupling is generally:
  • A Lower landing gear, disconnect lines, release fifth wheel, pull tractor away
  • B No specific order is required
  • C Pull tractor away first, then disconnect lines
  • D Release fifth wheel first, then connect lines
Correct answer: A
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 6 of 25
When the trailer begins to skid, you should:
  • A Disconnect the air supply
  • B Release the brakes to allow the trailer wheels to roll again, then steer
  • C Apply the trailer hand valve harder
  • D Accelerate
Correct answer: B
Releasing the brakes lets the wheels rotate again so the trailer can recover its tracking.
Question 7 of 25
A worn or damaged fifth wheel can cause:
  • A Rust on the cab
  • B Tire wear only
  • C Engine damage
  • 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 8 of 25
Off-tracking means:
  • A The trailer wheels follow a tighter arc than the tractor wheels in a turn
  • B Driving off the road
  • C Loss of traction
  • D Sliding sideways
Correct answer: A
In a right turn, the trailer wheels cut the corner. To compensate, the tractor must swing wider.
Question 9 of 25
Most rear-end collisions caused by combination vehicles result from:
  • A Worn out tires
  • B Cargo movement
  • C Engine failure
  • D Driving too fast for conditions and/or too closely
Correct answer: D
Speed and following distance dominate the causes. Increase cushion and slow down.
Question 10 of 25
Why should you not jackknife to get out of a tight spot?
  • A It is the standard procedure
  • B It is illegal in some states
  • C It is fine if you are careful
  • 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 11 of 25
You should test the air-brake system by:
  • A Pressing the pedal once at startup
  • B Listening to the brake light
  • C Performing the seven-step air-brake check before each trip
  • D Asking a mechanic
Correct answer: C
The seven-step check is the standard pre-trip air-brake test.
Question 12 of 25
The "service" line on a tractor-trailer:
  • A Carries electrical power
  • B Drains the trailer reservoir
  • C Sends supply air to the trailer reservoirs
  • D Sends air pressure to apply trailer service brakes
Correct answer: D
The service line carries braking-pressure changes from the foot valve to the trailer brakes.
Question 13 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 Stop on the tracks if traffic ahead slows
  • C Honk and accelerate
  • D Shift in the middle of the track
Correct answer: A
Cross in a low gear without shifting; never stop on the tracks; never shift in the middle.
Question 14 of 25
Tracking refers to:
  • A The fuel mileage
  • B The trailer following the same path as the tractor in a straight line
  • C Lane positioning at intersections
  • D Cargo placement
Correct answer: B
Tracking is how well the trailer follows the tractor; misalignment can indicate suspension or tire problems.
Question 15 of 25
When inspecting the air lines between tractor and trailer, look for:
  • A Engine oil leaks
  • B Cargo placement
  • 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 16 of 25
A "trailer skid" usually starts because:
  • A The tractor brakes lock up
  • B A wheel bearing fails
  • C The fifth wheel breaks
  • D The trailer brakes lock up
Correct answer: D
Locking the trailer brakes is the most common cause of a trailer skid (jackknife).
Question 17 of 25
If you cross the air lines (service to emergency and vice versa) when coupling:
  • A The trailer brakes will be locked on
  • B The horn will sound
  • C You will notice immediately because trailer brakes will not work properly
  • D Nothing will happen
Correct answer: C
Crossed glad hands often produce no air flow to brake chambers and incorrect brake operation; you should notice on the brake test.
Question 18 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 Drains the wet tank
  • D Operates the parking brake only
Correct answer: A
Loss of pressure on the emergency line causes the trailer's emergency brake to apply automatically.
Question 19 of 25
A combination vehicle with empty trailers:
  • A May actually take longer to stop because brakes are designed for the loaded weight
  • B Stops faster than when loaded
  • C Stops in the same distance
  • D Stops only with parking brake
Correct answer: A
Empty trailers can lock up easily and skid, which counterintuitively increases stopping distance.
Question 20 of 25
Which of the following can damage a fifth wheel?
  • A Coupling with the trailer too high
  • B Failure to grease
  • C All of the above
  • D Backing too fast
Correct answer: C
All three: high trailer skips the jaws, fast backing impacts hardware, and lack of lubrication accelerates wear.
Question 21 of 25
During a brake check before moving, you should look for:
  • A Steering wander only
  • B Pulling, sticking, or unusual feel as you apply the brakes
  • C Smoke from the cab
  • D Engine knocking
Correct answer: B
Low-speed brake test identifies pulling, sticking, or weakness so you don't discover it on the highway.
Question 22 of 25
You should inspect a combination vehicle for:
  • A Misalignment between tractor and trailer
  • B Loose or missing fifth-wheel mounting bolts
  • C Cracks in the kingpin
  • D All of the above
Correct answer: D
All three are pre-trip combination-vehicle items.
Question 23 of 25
The trailer hand valve should NOT be used to:
  • A Hold the vehicle when parking
  • B Both for parking and to prevent jackknife
  • C Apply trailer brakes momentarily
  • D Test the trailer brakes
Correct answer: B
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 24 of 25
The trailer hand valve operates:
  • A Both tractor and trailer brakes simultaneously
  • B The parking brake
  • C The trailer service brakes only
  • D The tractor service brakes only
Correct answer: C
The hand valve applies only the trailer service brakes. It is for testing — not for parking or routine use.
Question 25 of 25
Most tire problems on a combination vehicle:
  • A Can be detected during pre-trip inspection by visual and pressure checks
  • B Are caused by low fuel
  • C Show up only at high speed
  • D Need a mechanic to find
Correct answer: A
Visual and pressure checks catch most problems before they become roadside failures.

Study tips for the Massachusetts Combination Vehicles exam

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

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

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