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CDL knowledge test

CDL Combination Vehicles Practice Test 2026

For the Class A license: driving combination vehicles safely, combination air brakes, trailer antilock brakes, coupling and uncoupling, and inspecting a combination vehicle.

46 practice questions, all written from Commercial Driver's License Manual (Version 07/20/2026 (form DMV 60A), AAMVA, Virginia DMV edition). Every answer shows the manual section it comes from. Free, no sign-up.

  • 46 questions
  • 20 per attempt
  • Pass mark: 80%
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20 questions. Passing score: 80%. No sign-up needed.

Choose how you want to practice:

Test format

Passing score At least 80% correct (49 CFR 383.135 (eCFR))
Number of questions Varies by state. Check the CDL manual from your state’s licensing agency.
Our practice test 20 questions per attempt, drawn at random from 46. Pass mark: 80%.

Topics covered

  • Coupling and uncoupling 15 questions
  • Combination air brakes 11 questions
  • Driving combinations safely 11 questions
  • Inspecting a combination vehicle 5 questions
  • Trailer antilock brakes 4 questions

Sample questions

A few questions from the set. Try to answer before opening each explanation.

  1. Sample question 1

    What does ABS do for you during hard braking?

    • AIt always shortens your stopping distance on any road
    • BIt helps you keep control but may not shorten stopping distance
    • CIt adds extra braking power to your normal brakes
    • DIt lets you safely follow other vehicles more closely
    Show answer

    Answer: B. ABS works to prevent wheel lockup so you stay in control; it does not promise a shorter stop and adds no extra braking power.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 6.3.2 Braking with ABS.

  2. Sample question 2

    After backing under the trailer, how do you check that the trailer is locked onto the tractor?

    • ARelease the trailer brakes and back up firmly against it
    • BPull gently forward while the trailer brakes are still locked
    • CDrive a short loop around the lot with the landing gear down
    • DRock the trailer by hand from the rear bumper
    Show answer

    Answer: B. With the landing gear raised slightly off the ground, a gentle tug forward against the locked trailer brakes shows whether the trailer has latched onto the tractor.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 6.4.1 Coupling Tractor-Semitrailers.

  3. Sample question 3

    What problem can happen if the fifth wheel plate is not kept lubricated?

    • ASteering problems from tractor-trailer friction
    • BAir leaks at the glad hands when the rig turns
    • CThe landing gear will not raise all the way
    • DThe trailer lights will flicker or fail
    Show answer

    Answer: A. Without enough grease, the tractor and trailer rub against each other at the fifth wheel, and that friction can make the rig hard to steer.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 6.4.1 Coupling Tractor-Semitrailers.

  4. Sample question 4

    When uncoupling a loaded trailer, what should you do after the landing gear makes firm contact with the ground?

    • AStop cranking right away
    • BKeep cranking until the trailer lifts off the fifth wheel
    • CTurn the crank in low gear a few extra turns
    • DSwitch to high gear and crank until the gear is fully extended
    Show answer

    Answer: C. A few extra low-gear turns take some weight off the tractor without lifting the trailer off the fifth wheel, which makes unlatching and the next coupling easier.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 6.4.2 Uncoupling Tractor-Semitrailers.

  5. Sample question 5

    When might you first notice a major leak in the service line?

    • AWhen you first start the engine
    • BWhen you push in the trailer air supply control
    • CDuring a sharp turn
    • DWhen you try to put the brakes on
    Show answer

    Answer: D. A service line leak can stay hidden until you brake, when the escaping air quickly drops tank pressure and may set off the trailer emergency brakes.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 6.2.8 Trailer Service, Parking and Emergency Brakes.

How to prepare

  • Read the matching sections of your state’s CDL manual before you practice.
  • Use practice mode first: it shows the explanation and the manual reference after each answer.
  • For every missed question, reread the whole manual section we cite.
  • Switch to exam mode when you score well above 80% without help.

More detail in our guide How to Study for the CDL Knowledge Tests.

Other CDL practice tests

Which tests you need depends on your license class and endorsements, as explained in CDL Classes, Endorsements and Restrictions Explained.

Frequently asked questions

What score do I need to pass?

Federal rules require at least 80% correct on each CDL knowledge test (49 CFR 383.135 (eCFR)).

Are these the questions on the real test?

No. Real test questions are not public. We write our own questions from the official manual, so they cover the same material but are not copies of test questions.

Is the CDL manual the same in every state?

State CDL manuals are built on the same national model manual from AAMVA, so the knowledge content is largely the same. We compared 3 state editions for this test: 46 of 46 quotes appear word for word in the same section of all of them. Your own state’s manual is the final word if anything differs.

How do you check the answers?

Each question stores the manual section (or page) and an exact quote that a script checks against the manual text, then an independent AI review answers it from that part of the manual alone. See our editorial policy. Found a mistake? Tell us.

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20 questions, pass mark 80%. Free, no sign-up.

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Sources

Questions cite the newest edition we have. We also check every quote against the other state editions of the same model manual, section by section.