CDL Doubles and Triples (T) practice test

For the T endorsement, to pull two or three trailers. Class A only.

Examlane has 69 Doubles and Triples questions in 4 chapters. The usual test has 20 questions and needs 80% to pass. Some states set a different length: see the state table.

Chapters

Ten free questions

Open a question to see the answer and why.

1. 1. You are taking a set of doubles through a curving off ramp. What should you do to keep the trailers from rolling over?

   1. Speed up through the ramp so the trailers stay in line
   2. Use the speed that is safe for a straight truck
   3. Steer gently and go slowly
   4. Brake hard in the middle of the curve

   Answer: C. Steer gently and go slowly

   Doubles and triples roll over easily, so you must steer gently and slow down for corners, ramps, and curves.

   Based on: CDL manual, Section 7.1.1 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

2. 2. When you build a double bottom rig, which semitrailer should go first behind the tractor for the safest handling?

   1. The lighter semitrailer
   2. The more heavily loaded semitrailer
   3. The longer semitrailer
   4. The semitrailer that was loaded last

   Answer: B. The more heavily loaded semitrailer

   Put the more heavily loaded semitrailer in first position and the lighter one in the rear for the safest handling.

   Based on: CDL manual, Section 7.2.1 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

3. 3. How many steps are in the inspection procedure you use on a combination vehicle?

   1. Five
   2. Nine
   3. Eleven
   4. Seven

   Answer: D. Seven

   A combination vehicle is inspected with the seven-step inspection procedure.

   Based on: CDL manual, Section 7.3 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

4. 4. What is the starting point for checking brakes on a rig that pulls two or three trailers?

   1. Check them as you would on any combination vehicle
   2. Use a separate test made only for doubles and triples
   3. Check only the rear trailer's brakes
   4. Check only the tractor's brakes

   Answer: A. Check them as you would on any combination vehicle

   Begin by checking the brakes just as you would on any combination vehicle, then add the extra checks for the added trailers.

   Based on: CDL manual, Section 7.4 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

5. 5. Compared with other commercial vehicles, how stable are doubles and triples?

   1. More stable, because they have more axles
   2. About as stable as a single trailer rig
   3. More stable, because they weigh more
   4. Less stable

   Answer: D. Less stable

   More can go wrong with more than one trailer, and these rigs are less stable than other commercial vehicles.

   Based on: CDL manual, Section 7.1.1 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

6. 6. A converter dolly has no spring brakes. How do you release its brakes?

   1. Pull out the trailer air supply knob
   2. Disconnect the safety chains
   3. Lower the dolly support
   4. Open the air tank petcock

   Answer: D. Open the air tank petcock

   On a dolly without spring brakes, opening the air tank petcock releases the dolly brakes.

   Based on: CDL manual, Section 7.2.1 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

7. 7. Which item on a combination vehicle is just more of what you already check on a single vehicle?

   1. Pintle hook that tows the converter dolly
   2. Wheels and tires
   3. Converter dolly safety chains
   4. Shut-off valves on the back end of the trailers

   Answer: B. Wheels and tires

   Tires, wheels, lights, and reflectors are just more of what a single vehicle has, while the dolly and coupling parts are new things to check.

   Based on: CDL manual, Section 7.3 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

8. 8. You are about to test the air flow to every trailer. What should you use to keep the vehicle from moving?

   1. The engine brake
   2. The tractor parking brake, wheel chocks, or both
   3. The trailer air supply knob pulled out
   4. Nothing, because the trailer brakes will hold it

   Answer: B. The tractor parking brake, wheel chocks, or both

   Hold the vehicle with the tractor parking brake and / or wheel chocks while you test air flow.

   Based on: CDL manual, Section 7.4.1 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

9. 9. A set of triples makes a sudden steering move. Because of the crack-the-whip effect, which trailer has the greatest chance of rolling over?

   1. The last trailer
   2. The first trailer
   3. The middle trailer
   4. All three are equally likely

   Answer: A. The last trailer

   The whipping motion grows toward the back of the rig, so the last trailer is the one most likely to turn over.

   Based on: CDL manual, Section 7.1.2 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

10. 10. The converter dolly is not far from the rear trailer. How can you get it into position in front of that trailer?

    1. Wheel it into position by hand, in line with the kingpin
    2. Push it into place with the tractor's front bumper
    3. Drag it with a chain hooked to the tractor
    4. Lift it with the tractor's fifth wheel

    Answer: A. Wheel it into position by hand, in line with the kingpin

    When the distance is short, you can wheel the dolly by hand until it lines up with the kingpin.

    Based on: CDL manual, Section 7.2.1 (Georgia edition of the national model manual, read 2026-10-24). Question in our own words.

This is practice for the knowledge test. It is not Entry-Level Driver Training and does not count toward any federal training requirement.