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North Dakota Combination Vehicles CDL Practice Test

Below are 25 exam-style questions for the North Dakota Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the North Dakota Department of Transportation. 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
Which of the following can damage a fifth wheel?
  • A Coupling with the trailer too high
  • B All of the above
  • C Failure to grease
  • D Backing too fast
Correct answer: B
All three: high trailer skips the jaws, fast backing impacts hardware, and lack of lubrication accelerates wear.
Question 2 of 25
You should never back under a trailer that is:
  • A Properly chocked
  • B Loaded
  • C Empty
  • D Too high — it can damage the kingpin or skip over the fifth wheel
Correct answer: D
A trailer set too high can skip over the fifth-wheel jaws and not lock, or damage the coupling.
Question 3 of 25
The seven-pin connector on a tractor-trailer carries:
  • A Air for the brakes
  • B Electrical power for trailer lights and ABS
  • C Hydraulic fluid
  • D Fuel
Correct answer: B
The seven-pin (or older five-pin) is electrical, supplying lights, brake-light signal, and ABS.
Question 4 of 25
Brake-system pressure should be checked:
  • A Only at the start of the day
  • B Only at the destination
  • C Every 3 hours
  • D Before, during, and after coupling
Correct answer: D
Pressure changes during coupling indicate connection problems early.
Question 5 of 25
If you are pulling two trailers, the heavier trailer should be:
  • A Last
  • B Loaded last
  • C Either position is fine
  • D First (closest to the tractor)
Correct answer: D
Heavier trailer first reduces the rear-trailer crack-the-whip effect.
Question 6 of 25
A heavy combination vehicle in a curve is most likely to:
  • A Stop suddenly
  • B Roll over before sliding
  • C Lose engine power
  • D Spin out
Correct answer: B
Loaded trailers reach the rollover threshold before they slide. Slow before the curve.
Question 7 of 25
When backing a tractor-trailer, you should:
  • A Back to the left whenever possible because you can see better
  • B Back as fast as practical
  • C Back without using mirrors
  • D Always back to the right
Correct answer: A
Backing to the driver's side gives the best view of the trailer. Always GOAL — Get Out And Look — before and during.
Question 8 of 25
A tractor jackknife happens when:
  • A The fifth wheel disengages
  • B The tractor parking brake fails
  • C The trailer is too heavy
  • D The drive wheels lose traction and the tractor begins to slide
Correct answer: D
A drive-wheel skid causes the tractor to swing into the trailer at an angle.
Question 9 of 25
Tracking refers to:
  • A The fuel mileage
  • B Cargo placement
  • C Lane positioning at intersections
  • D The trailer following the same path as the tractor in a straight line
Correct answer: D
Tracking is how well the trailer follows the tractor; misalignment can indicate suspension or tire problems.
Question 10 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 No specific rule
  • C Two car lengths
  • 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 11 of 25
When you cross a railroad track in a combination vehicle, the safest practice is:
  • A Stop on the tracks if traffic ahead slows
  • B Cross in a low gear without shifting
  • C Shift in the middle of the track
  • D Honk and accelerate
Correct answer: B
Cross in a low gear without shifting; never stop on the tracks; never shift in the middle.
Question 12 of 25
A combination vehicle has a higher rollover risk because:
  • A Its tires are wider
  • B Its center of gravity is high
  • C It is shorter than a straight truck
  • D It uses air brakes
Correct answer: B
Loaded trailers have high centers of gravity; rollover happens at speeds the driver thinks are safe.
Question 13 of 25
Why should you not jackknife to get out of a tight spot?
  • A It is the standard procedure
  • B It is fine if you are careful
  • C It is illegal in some states
  • 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
When inspecting the air lines between tractor and trailer, look for:
  • A Loose lug nuts only
  • B Engine oil leaks
  • C Cargo placement
  • D Cuts, abrasions, and worn seals
Correct answer: D
Air-line condition is a typical roadside inspection focus on combinations.
Question 15 of 25
A skid is most likely to result in a jackknife if:
  • A You are driving slowly
  • B The drive wheels lock and the trailer pushes the tractor sideways
  • C The brakes are released gently
  • D The trailer wheels lock briefly
Correct answer: B
Drive-wheel lockup is the classic jackknife cause.
Question 16 of 25
Which is true about combination braking?
  • A Brake balance is irrelevant
  • B Trailer wheels lock more often than drive wheels in panic stops
  • C Drive wheels never lock
  • D ABS prevents jackknife in all cases
Correct answer: B
Empty trailer wheels lock easily and contribute to jackknife and trailer-swing risks.
Question 17 of 25
When parking a tractor-trailer, you should:
  • A Set only the tractor parking brake
  • B Set both tractor and trailer parking brakes
  • C Use the trailer hand valve
  • D Leave the engine running with the brakes off
Correct answer: B
For full parking, both parking brakes apply.
Question 18 of 25
When backing a trailer, small steering inputs cause:
  • A Large trailer angle changes; small inputs are key
  • B Small trailer movement
  • C Loss of brake pressure
  • D No effect
Correct answer: A
Trailer responds aggressively to small wheel inputs in reverse — back slowly and correct quickly.
Question 19 of 25
Most rear-end collisions caused by combination vehicles result from:
  • A Cargo movement
  • B Worn out tires
  • 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 20 of 25
The proper test of a good fifth-wheel coupling is:
  • A Tug the trailer with the trailer parking brakes set
  • B Look at the locking jaws only
  • C Honk the horn
  • D Listen for a click
Correct answer: A
After coupling and locking, gently pull forward against the locked trailer brakes to confirm engagement.
Question 21 of 25
After coupling, the locking jaws should:
  • A Be open
  • B Be closed around the shank of the kingpin (not on the head)
  • C Be missing
  • D Be loose
Correct answer: B
Visual check: jaws around the shank, not the head. A flashlight helps.
Question 22 of 25
Which is true about coupling order to a trailer?
  • A Connect any line first; order doesn't matter
  • B Connect air emergency line first, then service line, then electrical (or per company policy) — verify with brake check
  • C Connect electrical first, then air
  • D Connect only air; electrical is optional
Correct answer: B
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
During a brake check before moving, you should look for:
  • A Engine knocking
  • B Smoke from the cab
  • C Pulling, sticking, or unusual feel as you apply the brakes
  • D Steering wander only
Correct answer: C
Low-speed brake test identifies pulling, sticking, or weakness so you don't discover it on the highway.
Question 24 of 25
After connecting the air lines, before pulling the tractor away, you must:
  • A Pump the brakes 10 times
  • B Charge the trailer brakes by setting the trailer air supply control
  • C Drive away immediately
  • D Drain the wet tank
Correct answer: B
After connecting, charge the trailer system and verify brake operation.
Question 25 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).

Study tips for the North Dakota Combination Vehicles exam

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

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

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