Alabama Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the Alabama Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the Alabama Law Enforcement Agency (ALEA) Driver License Division. 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.
- A The trailer service brakes only
- B The parking brake
- C The tractor service brakes only
- D Both tractor and trailer brakes simultaneously
- A Be closed around the shank of the kingpin (not on the head)
- B Be loose
- C Be open
- D Be missing
- A Fuel
- B Electrical power for trailer lights and ABS
- C Hydraulic fluid
- D Air for the brakes
- A Lowered to the ground while driving
- B Always halfway extended
- C Fully raised before driving
- D Disconnected before driving
- A Off-tracking — the trailer wheels follow a tighter arc than the tractor
- B Wheel damage
- C Brake fade
- D No off-tracking
- A Cross in a low gear without shifting
- B Honk and accelerate
- C Shift in the middle of the track
- D Stop on the tracks if traffic ahead slows
- A Maximum legal height
- B Whatever height it happens to be
- C A height that requires the tractor to drop down to fit
- D A height where the tractor will lift the trailer slightly when backing under
- A Connect only air; electrical is optional
- B Connect electrical first, then air
- C Connect air emergency line first, then service line, then electrical (or per company policy) — verify with brake check
- D Connect any line first; order doesn't matter
- A Cargo movement
- B Driving too fast for conditions and/or too closely
- C Worn out tires
- D Engine failure
- A Replaces the fifth wheel on the tractor
- B Is part of the tractor
- C Is used only when triple-towing
- D Is used to convert a semitrailer into a full trailer for towing in combination
- A Two car lengths
- B One second per 10 feet of vehicle length below 40 mph, plus one extra second above 40 mph
- C A vehicle length
- D No specific rule
- A Listen for a click
- B Look at the locking jaws only
- C Tug the trailer with the trailer parking brakes set
- D Honk the horn
- A Set both tractor and trailer parking brakes
- B Leave the engine running with the brakes off
- C Set only the tractor parking brake
- D Use the trailer hand valve
- A Stop in the middle of the turn
- B Swing wide to the right first to avoid hitting the curb
- C Keep the cab close to the curb and swing the front out so following cars cannot squeeze beside you on the right
- D Swing left then right
- A Air leakage in the supply line, low pressure, or a brake-balance issue
- B Cargo placement
- C Engine wear
- D Driver fatigue
- A Its tires are wider
- B It uses air brakes
- C It is shorter than a straight truck
- D Its center of gravity is high
- A Brake adjustment levers
- B Electrical connectors
- C Manual transmission shifters
- D Coupling devices for connecting tractor air lines to the trailer
- A All of the above
- B Coupling with the trailer too high
- C Failure to grease
- D Backing too fast
- A Are caused by low fuel
- B Show up only at high speed
- C Need a mechanic to find
- D Can be detected during pre-trip inspection by visual and pressure checks
- A Lose engine power
- B Spin out
- C Stop suddenly
- D Roll over before sliding
- A Too high — it can damage the kingpin or skip over the fifth wheel
- B Empty
- C Loaded
- D Properly chocked
- A The trailer brakes will be locked on
- B The horn will sound
- C Nothing will happen
- D You will notice immediately because trailer brakes will not work properly
- A Triangular, green, marked SERVICE
- B Round, blue, marked TRACTOR
- C Square, white, marked CHARGE
- D Octagonal, red, marked TRAILER AIR SUPPLY
- A Last
- B Either position is fine
- C First (closest to the tractor)
- D Loaded last
- A Stop traffic by signaling left
- B Turn from the left lane
- 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 Use the shoulder
Study tips for the Alabama Combination Vehicles exam
The Combination Vehicles portion of the Alabama CDL exam is graded out of the bank of questions the Alabama Law Enforcement Agency (ALEA) Driver License Division draws from each year. While the exact bank is not published, every question is sourced from the Combination Vehicles chapter of the Alabama 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 Alabama 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 Alabama Law Enforcement Agency (ALEA) Driver License Division 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 Alabama 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 Alabama 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 Alabama Law Enforcement Agency (ALEA) Driver License Division office.
Already comfortable with this endorsement? Drill another: AL General Knowledge · AL Air Brakes · AL Hazardous Materials · AL Passenger · AL School Bus · AL Tank Vehicle · AL Doubles / Triples
New to the CDL process in Alabama? Read How to apply for a CDL in Alabama for the document checklist and step-by-step timeline.