PassEveryTest
Nederlands

CDL Doubles and Triples Practice Test 2026

The doubles/triples (T) endorsement lets you pull two or three trailers. These questions cover the extra rollover risk, coupling and uncoupling with a converter dolly, shut-off valve positions and the air brake checks.

  • Bedrijfsvoertuig
  • Verenigde Staten
  • 50 vragen
  • Gecontroleerd op 10 oktober 2026

Kort antwoord

Het officiële examen heeft 20 vragen. Geslaagd: Varies by state; usually 20 questions, with 16 correct needed (80%). Afgenomen door: Your state driver licensing agency, under federal rules set by FMCSA (49 CFR Part 383). Oefen hier gratis met 50 vragen, elk met het antwoord en een uitleg. Gecontroleerd aan de hand van officiële bronnen op 10 oktober 2026.

Lees dit voordat je gaat oefenenBegin met de CDL Doubles and Triples Study Guide: notities in begrijpelijke taal, schema’s en de getallen die je moet onthouden.

  1. Vraag 1 van 25

    Compared with other combinations, how likely are doubles and triples to turn over?
    Toon antwoord

    Antwoord: D. More likely

    Doubles and triples are more likely to turn over than other combination vehicles.

  2. Vraag 2 van 25

    Which trailer in a double or triple is most likely to turn over?
    Toon antwoord

    Antwoord: D. The last trailer

    Because of the crack-the-whip effect, the last trailer is the most likely to turn over.

  3. Vraag 3 van 25

    Compared with a five-axle tractor-semitrailer, how much more easily can the last trailer of a triple roll over?
    Toon antwoord

    Antwoord: A. About 3.5 times as easily

    Triples have the highest rearward amplification. The last trailer can roll about 3.5 times as easily.

  4. Vraag 4 van 25

    A speed that is safe for a single trailer on a curve is not always safe for doubles. Why?
    Toon antwoord

    Antwoord: D. Doubles and triples roll over more easily

    A speed that is fine for a straight truck or single trailer may be too fast for doubles or triples.

  5. Vraag 5 van 25

    What is the crack-the-whip effect?
    Toon antwoord

    Antwoord: D. A quick steering move swings the rear trailer much more

    Sudden steering is amplified toward the back of the rig. This rearward amplification can tip over the last trailer.

  6. Vraag 6 van 25

    Why do doubles and triples need extra care in the pre-trip inspection?
    12345678
    Toon antwoord

    Antwoord: C. They have more critical parts to check

    With two or three trailers, there are more parts that must be checked.

  7. Vraag 7 van 25

    Why should you look far ahead when pulling doubles or triples?
    Toon antwoord

    Antwoord: C. So you can slow down or change lanes gradually

    Drive very smoothly to avoid rollover or jackknife. Looking far ahead gives you time for gradual changes.

  8. Vraag 8 van 25

    How should your following distance compare when pulling doubles or triples?
    Toon antwoord

    Antwoord: A. Allow more following distance

    Doubles and triples are longer and cannot turn or stop suddenly, so leave more space ahead.

  9. Vraag 9 van 25

    Why are doubles and triples more likely to skid in bad weather?
    Toon antwoord

    Antwoord: B. Greater length and more dead axles mean less traction

    Be especially careful on slippery roads and in mountains. Length and extra axles raise the risk of skids.

  10. Vraag 10 van 25

    What should you avoid when parking doubles or triples?
    Toon antwoord

    Antwoord: A. A spot you cannot pull straight out of

    Plan your parking so you can pull straight through and avoid a long, difficult way out.

  11. Vraag 11 van 25

    Converter dollies built on or after March 1, 1998 must have which safety feature?
    Toon antwoord

    Antwoord: C. Antilock brakes, with a yellow lamp on the left

    Converter dollies built on or after March 1, 1998 must have antilock brakes and a yellow ABS lamp on the left side.

  12. Vraag 12 van 25

    Which trailer should go first, right behind the tractor?
    Toon antwoord

    Antwoord: C. The more heavily loaded one

    Put the heaviest trailer first, behind the tractor. The lighter trailer goes at the rear.

  13. Vraag 13 van 25

    Where should the lighter trailer go in a set of doubles?
    Toon antwoord

    Antwoord: B. At the rear

    The lighter trailer goes in the rear, and the heavier one goes first.

  14. Vraag 14 van 25

    The rear trailer has no spring brakes. How can you secure it before coupling?
    Toon antwoord

    Antwoord: B. Charge its tank, then disconnect the emergency line

    Charging the tank and disconnecting the emergency line sets the trailer's emergency brakes (if the slack adjusters are right). Chock the wheels if in doubt.

  15. Vraag 15 van 25

    You are not sure the rear trailer's brakes will hold. What should you do?
    Toon antwoord

    Antwoord: A. Chock the wheels

    If you have any doubt about the trailer brakes, chock the wheels.

  16. Vraag 16 van 25

    How do you release the brakes on a converter dolly that has no spring brakes?
    Toon antwoord

    Antwoord: A. Open the air tank petcock

    Open the dolly's air tank petcock to release its brakes. If the dolly has spring brakes, use the dolly parking brake control.

  17. Vraag 17 van 25

    The converter dolly is close to the rear trailer. How can you move it into place?
    Toon antwoord

    Antwoord: A. Wheel it by hand so it lines up with the kingpin

    If the distance is short, you can wheel the dolly by hand into line with the kingpin.

  18. Vraag 18 van 25

    After hooking the dolly to the first trailer, what must you do with the pintle hook?
    Toon antwoord

    Antwoord: D. Lock it

    Hook the dolly to the front trailer, lock the pintle hook, and secure the converter gear support in the raised position.

  19. Vraag 19 van 25

    Before backing the dolly under the rear trailer, how high should the trailer be?
    Toon antwoord

    Antwoord: D. Slightly lower than the dolly's fifth wheel

    The trailer must be a little low so it is raised slightly when the dolly is pushed under it.

  20. Vraag 20 van 25

    Why raise the rear trailer's landing gear slightly off the ground right after backing the dolly under it?
    Toon antwoord

    Antwoord: C. To prevent damage if the trailer moves

    Raise the landing gear just off the ground so it is not damaged if the trailer moves during the tug test.

  21. Vraag 21 van 25

    How do you test the coupling between the dolly and the second trailer?
    Toon antwoord

    Antwoord: C. Pull against the second trailer's kingpin

    Test the coupling by pulling gently against the second trailer's kingpin.

  22. Vraag 22 van 25

    During the visual check of the dolly coupling, what should you see?
    Toon antwoord

    Antwoord: A. No gap between the fifth wheel plates, jaws closed on the kingpin

    There should be no space between the fifth wheel surfaces, and the jaws must be closed on the kingpin.

  23. Vraag 23 van 25

    After coupling the dolly, what must you connect between the trailers?
    Toon antwoord

    Antwoord: D. Safety chains, air hoses and light cords

    Connect the safety chains, air hoses and light cords.

  24. Vraag 24 van 25

    After coupling doubles, what do you do with the shut-off valves at the rear of the second (last) trailer?
    Toon antwoord

    Antwoord: C. Close them

    Close the dolly air tank petcock and the shut-off valves at the rear of the last trailer.

  25. Vraag 25 van 25

    After coupling doubles, what do you do with the shut-off valves at the rear of the first trailer?
    Toon antwoord

    Antwoord: D. Open them

    Open the shut-off valves at the rear of the first trailer, and on the dolly if it has them, so air reaches the second trailer.

Wat je moet weten voor het examen

  • Federal rules set the passing score for every CDL knowledge test: you must answer at least 80% of the questions correctly.
  • The doubles/triples test has 20 questions in states such as Washington and Illinois, so you need 16 correct answers.
  • The double/triple trailers endorsement needs a knowledge test only.
  • The T endorsement cannot be placed on a commercial learner's permit.
  • Converter dollies built on or after March 1, 1998 must have antilock brakes, with a yellow lamp on the left side.

Veelgestelde vragen

How many questions are on the doubles and triples test?

Each state sets the number, but Washington and Illinois both use 20 questions. You need 16 correct to pass.

Is there a skills test for doubles and triples?

No. The T endorsement needs a knowledge test only.

Which trailer goes first in a set of doubles?

The more heavily loaded trailer goes first, right behind the tractor. The lighter trailer goes at the rear.

Which shut-off valves should be closed?

Only the ones at the rear of the last trailer. All others must be open so air reaches every trailer's brakes.

Bronnen

Gerelateerde examens