CDL Doubles and Triples Practice Test 2026: Quiz di prova 2

1. Domanda 1 di 25

   After charging the trailer brakes, how do you check that air reaches the last trailer?

   • ADrive off and see whether the last trailer stops
   • BLook only at the tractor's air pressure gauge
   • COpen the rear emergency line shut-off and listen
   • DCheck the tire pressure on the last trailer
   Mostra la risposta

   Risposta: C. Open the rear emergency line shut-off and listen

   Open the emergency shut-off at the back of the last trailer. If there is no air, the brakes won't work.

2. Domanda 2 di 25

   You open the shut-off at the rear of the last trailer and hear no air. What is the most likely cause?

   • AThe fifth wheel has too much grease
   • BThe trailer lights are turned off
   • CA shut-off valve upstream is closed
   • DThe tires on the last trailer are low
   Mostra la risposta

   Risposta: C. A shut-off valve upstream is closed

   If air does not reach the back, check that the shut-off valves on all trailers and the dolly are open.

3. Domanda 3 di 25

   When uncoupling the rear trailer, where should you park the rig?

   • AOn a curve
   • BOn a slope so the trailer rolls free
   • CIn a straight line on firm, level ground
   • DOn soft ground
   Mostra la risposta

   Risposta: C. In a straight line on firm, level ground

   Park in a straight line on firm, level ground and apply the parking brakes before uncoupling.

4. Domanda 4 di 25

   When uncoupling the rear trailer, why lower its landing gear first?

   • ATo raise the trailer brakes
   • BTo release the pintle hook
   • CTo take some weight off the dolly
   • DTo drain the air tanks
   Mostra la risposta

   Risposta: C. To take some weight off the dolly

   Lower the second trailer's landing gear enough to remove some weight from the dolly.

5. Domanda 5 di 25

   When uncoupling, which shut-offs do you close before disconnecting the dolly lines?

   • ANone; leave every shut-off open
   • BOnly the shut-offs on the tractor
   • CThe drain valves on the rear trailer
   • DThose at the rear of the first trailer
   Mostra la risposta

   Risposta: D. Those at the rear of the first trailer

   Close the air shut-offs at the rear of the first semitrailer, and on the dolly if it has them.

6. Domanda 6 di 25

   How do you get the dolly out from under the rear trailer?

   • ABack the tractor and first trailer into the dolly
   • BRelease the dolly fifth wheel latch and pull slowly forward
   • CLift the rear trailer with a jack and roll the dolly out
   • DUnlock the pintle hook first and then drive away
   Mostra la risposta

   Risposta: B. Release the dolly fifth wheel latch and pull slowly forward

   Release the converter dolly fifth wheel latch, then slowly pull forward to draw the dolly out.

7. Domanda 7 di 25

   Why must you never unlock the pintle hook with the dolly still under the rear trailer?

   • AThe trailer lights may fail
   • BThe dolly tow bar may fly up
   • CThe air lines may freeze up
   • DThe trailer may roll forward
   Mostra la risposta

   Risposta: B. The dolly tow bar may fly up

   The tow bar can fly up, causing injury and making it very hard to couple again.

8. Domanda 8 di 25

   When unhooking the converter dolly from the first trailer, what do you do before releasing the pintle hook?

   • ALower its gear, unhook the chains, and secure it
   • BOpen all the shut-off valves on both trailers
   • CRaise the dolly landing gear all the way up
   • DConnect the light cord to the rear trailer
   Mostra la risposta

   Risposta: A. Lower its gear, unhook the chains, and secure it

   Lower the dolly's support, unhook the chains, and secure the dolly before releasing the pintle hook and pulling clear.

9. Domanda 9 di 25

   How do you couple a set of triples?

   • AHook the third trailer to the tractor first
   • BUse a fifth wheel between trailers and no dollies
   • CCouple the first trailer, then add the rest like doubles
   • DCouple all three trailers first, then back under them
   Mostra la risposta

   Risposta: C. Couple the first trailer, then add the rest like doubles

   Couple the tractor to the first trailer as for any semitrailer, then use the converter dolly method for the rest.

10. Domanda 10 di 25

    When uncoupling triples, which trailer do you uncouple first?

    • AThe third (last) trailer
    • BAny of the three
    • CThe middle trailer
    • DThe first trailer
    Mostra la risposta

    Risposta: A. The third (last) trailer

    Uncouple the third trailer by pulling the dolly out, then handle the rest like a double.

11. Domanda 11 di 25

    You drive a combination type not covered in your manual. How should you couple it?

    • AUse the triples method for every rig
    • BFollow the maker's or owner's instructions
    • CAsk another driver to guess the steps
    • DCouple it any way that seems to work
    Mostra la risposta

    Risposta: B. Follow the maker's or owner's instructions

    There are many other combinations. Know the manufacturer and owner specifications for the vehicles you drive.

12. Domanda 12 di 25

    During inspection of doubles, what position should the shut-off valves at the rear of the front trailer be in?

    • AClosed
    • BOpen
    • CRemoved
    • DHalfway
    Mostra la risposta

    Risposta: B. Open

    Shut-offs at the rear of front trailers must be open so air flows back. Only those at the rear of the last trailer are closed.

13. Domanda 13 di 25

    During inspection, what position should the converter dolly air tank drain valve be in?

    • ARemoved
    • BClosed
    • COpen
    • DIt does not matter
    Mostra la risposta

    Risposta: B. Closed

    The converter dolly air tank drain valve should be closed.

14. Domanda 14 di 25

    What should you check on the pintle hook during inspection?

    • AThe hook is freshly painted and clean
    • BThe pintle eye is in the hook and it is latched
    • CThe hook is mounted under the last trailer
    • DThe hook is open so it releases easily
    Mostra la risposta

    Risposta: B. The pintle eye is in the hook and it is latched

    The dolly pintle eye must be in the trailer's pintle hook, and the hook must be latched.

15. Domanda 15 di 25

    Which of these should you check on a double during the walkaround?

    • ASafety chains removed so they don't drag
    • BLight cords left loose for easy unplugging
    • CSafety chains secured and light cords firmly plugged in
    • DAir lines resting on the ground between trailers
    Mostra la risposta

    Risposta: C. Safety chains secured and light cords firmly plugged in

    Check that safety chains are secured, light cords are firmly in place, and air lines are supported.

16. Domanda 16 di 25

    Your converter dolly carries a spare tire. What should you check?

    • AThat it is chained to the pintle hook
    • BThat it is removed for the trip
    • CThat it is secured
    • DThat it is flat
    Mostra la risposta

    Risposta: C. That it is secured

    Any spare tire on the converter dolly must be secured.

17. Domanda 17 di 25

    For the air flow check on doubles, what do you do after pressure is normal?

    • APull out the yellow parking brake knob
    • BTurn off the battery switch in the cab
    • COpen all the drain valves on the trailers
    • DPush in the red knob, then use the hand brake
    Mostra la risposta

    Risposta: D. Push in the red knob, then use the hand brake

    Push in the red knob to supply the trailers, use the trailer hand brake to send air to the service line, then check at the rear.

18. Domanda 18 di 25

    After checking the emergency line at the rear of the last trailer, what else should you check there?

    • AThat service air reaches the last trailer
    • BThat the tank drain valve is open
    • CThat the trailer lights are switched off
    • DThat the landing gear is lowered
    Mostra la risposta

    Risposta: A. That service air reaches the last trailer

    Open the service line valve at the rear to check that service pressure reaches all trailers, then close it.

19. Domanda 19 di 25

    When testing the tractor protection valve on doubles, the control should pop out at about what pressure?

    • AAbout 150 psi
    • BAbout 20 to 45 psi
    • CAbout 125 psi
    • DAbout 100 psi
    Mostra la risposta

    Risposta: B. About 20 to 45 psi

    Lower the pressure by stepping on and off the brake. The control should pop out, usually between 20 and 45 psi.

20. Domanda 20 di 25

    What could happen if the tractor protection valve does not work?

    • AThe engine would overheat on long climbs
    • BThe trailers would uncouple on their own
    • CA leak could drain the tractor's air supply
    • DThe trailer lights would stay on all night
    Mostra la risposta

    Risposta: C. A leak could drain the tractor's air supply

    If the valve fails, a leak could drain all the tractor's air, applying the emergency brakes and possibly causing loss of control.

21. Domanda 21 di 25

    How do you test the trailer emergency brakes on doubles?

    • APull out the trailer air supply, then pull gently
    • BPress the brake pedal hard at highway speed
    • CUnlock the pintle hook and drive forward
    • DOpen the converter dolly's drain valve
    Mostra la risposta

    Risposta: A. Pull out the trailer air supply, then pull gently

    First make sure the trailers roll freely, then pull out the supply control and pull gently against the brakes.

22. Domanda 22 di 25

    Which letter on a CDL shows the double/triple trailers endorsement?

    • AN
    • BS
    • CT
    • DX
    Mostra la risposta

    Risposta: C. T

    The T endorsement covers double and triple trailers.

23. Domanda 23 di 25

    What kind of test is needed for the doubles/triples endorsement?

    • AA knowledge test and a skills test
    • BA skills test only
    • CNo test
    • DA knowledge test only
    Mostra la risposta

    Risposta: D. A knowledge test only

    The double/triple trailer endorsement requires a knowledge test.

24. Domanda 24 di 25

    Can a commercial learner's permit (CLP) carry a doubles/triples (T) endorsement?

    • AOnly for empty trailers
    • BYes, if you are over 21
    • CNo
    • DYes, always
    Mostra la risposta

    Risposta: C. No

    Only passenger, school bus and tank endorsements are allowed on a CLP.

25. Domanda 25 di 25

    Your double rig is 70 feet long and you are traveling at 50 mph. What following distance should you keep?

    • AAt least 8 seconds
    • BAt least 7 seconds
    • CAt least 3 seconds
    • DAt least 5 seconds
    Mostra la risposta

    Risposta: A. At least 8 seconds

    Allow 1 second for each 10 feet (7 seconds), plus 1 second because you are above 40 mph.

Tastiera: 1–4 per rispondere, Invio per la domanda successiva.

Il test reale: Varies by state; usually 20 questions, with 16 correct needed (80%)