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AK · GK (Class A) Endorsement

Alaska Combination Vehicles CDL Practice Test

Below are 25 exam-style questions for the Alaska Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Alaska Division 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
The "service" line on a tractor-trailer:
  • A Sends air pressure to apply trailer service brakes
  • B Drains the trailer reservoir
  • C Sends supply air to the trailer reservoirs
  • D Carries electrical power
Correct answer: A
The service line carries braking-pressure changes from the foot valve to the trailer brakes.
Question 2 of 25
When inspecting the air lines between tractor and trailer, look for:
  • A Loose lug nuts only
  • B Cuts, abrasions, and worn seals
  • C Cargo placement
  • D Engine oil leaks
Correct answer: B
Air-line condition is a typical roadside inspection focus on combinations.
Question 3 of 25
When the trailer begins to skid, you should:
  • A Disconnect the air supply
  • B Accelerate
  • C Apply the trailer hand valve harder
  • D Release the brakes to allow the trailer wheels to roll again, then steer
Correct answer: D
Releasing the brakes lets the wheels rotate again so the trailer can recover its tracking.
Question 4 of 25
A heavy combination vehicle in a curve is most likely to:
  • A Lose engine power
  • B Spin out
  • C Roll over before sliding
  • D Stop suddenly
Correct answer: C
Loaded trailers reach the rollover threshold before they slide. Slow before the curve.
Question 5 of 25
When you turn a combination vehicle right at an intersection, you should:
  • A Keep the cab close to the curb and swing the front out so following cars cannot squeeze beside you on the right
  • B Swing left then right
  • C Swing wide to the right first to avoid hitting the curb
  • D Stop in the middle of the turn
Correct answer: A
Hugging the right side of the turn lane prevents another vehicle from squeezing in next to you and getting clipped by the trailer.
Question 6 of 25
A skid is most likely to result in a jackknife if:
  • A The brakes are released gently
  • B The drive wheels lock and the trailer pushes the tractor sideways
  • C The trailer wheels lock briefly
  • D You are driving slowly
Correct answer: B
Drive-wheel lockup is the classic jackknife cause.
Question 7 of 25
When you make a wide right turn, you should:
  • A Stop traffic by signaling left
  • B Use the shoulder
  • C Stay in the right lane and swing the front of the tractor wide enough to clear the curb without inviting cars to pass on the right
  • D Turn from the left lane
Correct answer: C
Use only as much room as needed and keep the right side blocked to following vehicles.
Question 8 of 25
When a tractor pulls a trailer with brakes that are out of balance:
  • A Stopping distances are normal
  • B Steering becomes easier
  • C Stopping distances increase and the trailer can swing
  • D No effect on safety
Correct answer: C
Brake imbalance makes the rig pull, lengthens stopping distance, and increases the chance of trailer swing.
Question 9 of 25
When uncoupling, after the tractor is clear, you should:
  • A Disable the trailer parking brake
  • B Check that the trailer is stable on its landing gear
  • C Connect the lines back to the tractor
  • D Move the tractor far away immediately without checking
Correct answer: B
Verify the trailer is sitting solidly before leaving the area.
Question 10 of 25
The fifth-wheel locking lever should be:
  • A Locked and the safety latch in place after coupling
  • B Tied with rope
  • C Removed before driving
  • D Released and visible after coupling
Correct answer: A
After backing under, the locking jaws must close around the kingpin and the safety latch must be in place.
Question 11 of 25
A safe combination-vehicle following distance is at least:
  • A Two car lengths
  • B A vehicle length
  • C No specific rule
  • D One second per 10 feet of vehicle length below 40 mph, plus one extra second above 40 mph
Correct answer: D
A 60-ft combination needs at least 6 seconds under 40 mph, 7 seconds above 40 mph.
Question 12 of 25
The seven-pin connector on a tractor-trailer carries:
  • A Electrical power for trailer lights and ABS
  • B Fuel
  • C Hydraulic fluid
  • D Air for the brakes
Correct answer: A
The seven-pin (or older five-pin) is electrical, supplying lights, brake-light signal, and ABS.
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 can damage the cab and the trailer (cab corner crush)
  • C It is the standard procedure
  • D It is illegal in some states
Correct answer: B
Bending the tractor too sharply against the trailer can cause body damage and disconnect the lines.
Question 14 of 25
Trailer air supply valves on tractors are typically:
  • A Triangular, green, marked SERVICE
  • B Round, blue, marked TRACTOR
  • C Octagonal, red, marked TRAILER AIR SUPPLY
  • D Square, white, marked CHARGE
Correct answer: C
The trailer air-supply valve is the red, octagonal knob — a federal standard.
Question 15 of 25
You should never back under a trailer that is:
  • A Properly chocked
  • B Empty
  • C Loaded
  • 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 16 of 25
You should test the air-brake system by:
  • A Performing the seven-step air-brake check before each trip
  • B Listening to the brake light
  • C Pressing the pedal once at startup
  • D Asking a mechanic
Correct answer: A
The seven-step check is the standard pre-trip air-brake test.
Question 17 of 25
A converter dolly:
  • A Is used to convert a semitrailer into a full trailer for towing in combination
  • B Replaces the fifth wheel on the tractor
  • C Is part of the tractor
  • D Is used only when triple-towing
Correct answer: A
A converter dolly turns a semitrailer into a full trailer that can be coupled behind another trailer.
Question 18 of 25
Which of the following can damage a fifth wheel?
  • A Coupling with the trailer too high
  • B Failure to grease
  • C Backing too fast
  • D All of the above
Correct answer: D
All three: high trailer skips the jaws, fast backing impacts hardware, and lack of lubrication accelerates wear.
Question 19 of 25
Trailer parking brakes are released:
  • A By the trailer hand valve
  • B By pushing in the red trailer-air-supply valve
  • C By pulling out the red trailer-air-supply valve
  • D By setting the red trailer-air-supply valve
Correct answer: B
Pushing in the red knob charges the trailer brakes and releases the spring brakes.
Question 20 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 Engine failure
  • D Cargo movement
Correct answer: A
Speed and following distance dominate the causes. Increase cushion and slow down.
Question 21 of 25
The proper test of a good fifth-wheel coupling is:
  • A Honk the horn
  • B Listen for a click
  • C Look at the locking jaws only
  • 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 22 of 25
The crank handle on the landing gear should:
  • A Be in the stowed (high) position when traveling
  • B Be locked at half-height
  • C Be removed
  • D Be in the low position when traveling
Correct answer: A
Stow the crank up so it doesn't catch on something while traveling.
Question 23 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 24 of 25
The trailer hand valve should NOT be used to:
  • A Apply trailer brakes momentarily
  • B Test the trailer brakes
  • 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 25 of 25
Before pulling the kingpin release lever to uncouple, you must:
  • A Honk the horn
  • B Drain the air tanks
  • C Lower the trailer landing gear and chock the trailer wheels
  • D Disconnect the electrical line first
Correct answer: C
Always lower the landing gear and chock the trailer so it cannot move once you pull out from under it.

Study tips for the Alaska Combination Vehicles exam

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

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

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