CDL Doubles and Triples Practice Test 2026: الاختبار التدريبي 2

1. السؤال 1 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 2 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 3 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 4 من 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
   أظهر الإجابة

   الإجابة: C. To take some weight off the dolly

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

5. السؤال 5 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 6 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 7 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 8 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 9 من 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
   أظهر الإجابة

   الإجابة: 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. السؤال 10 من 25

    When uncoupling triples, which trailer do you uncouple first?

    • AThe third (last) trailer
    • BAny of the three
    • CThe middle trailer
    • DThe first trailer
    أظهر الإجابة

    الإجابة: A. The third (last) trailer

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

11. السؤال 11 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 12 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 13 من 25

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

    • ARemoved
    • BClosed
    • COpen
    • DIt does not matter
    أظهر الإجابة

    الإجابة: B. Closed

    The converter dolly air tank drain valve should be closed.

14. السؤال 14 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 15 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 16 من 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
    أظهر الإجابة

    الإجابة: C. That it is secured

    Any spare tire on the converter dolly must be secured.

17. السؤال 17 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 18 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 19 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 20 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 21 من 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
    أظهر الإجابة

    الإجابة: 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. السؤال 22 من 25

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

    • AN
    • BS
    • CT
    • DX
    أظهر الإجابة

    الإجابة: C. T

    The T endorsement covers double and triple trailers.

23. السؤال 23 من 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
    أظهر الإجابة

    الإجابة: D. A knowledge test only

    The double/triple trailer endorsement requires a knowledge test.

24. السؤال 24 من 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
    أظهر الإجابة

    الإجابة: C. No

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

25. السؤال 25 من 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
    أظهر الإجابة

    الإجابة: A. At least 8 seconds

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

لوحة المفاتيح: 1–4 للإجابة، وEnter للسؤال التالي.

الاختبار الحقيقي: Varies by state; usually 20 questions, with 16 correct needed (80%)