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  • Updated for April 2025
  • Based on 2025 ND commercial driver's license manual

Free ND CDL Double/Triple Trailers Practice Test 2025

If you want to pull doubles or triples for a living, you should be glad you’re living in North Dakota. Double Pup trailers are legal nationwide, but North Dakota also allows other types of Long Combination Vehicles (LCVs) on officially designated routes: Rocky Mountain Double, Turnpike Double, and Triple. (However, you may need an oversize permit if your vehicle exceeds the state’s length or weight limits.) Several of the state’s key economic sectors use Doubles or Triples for transport.

In much of the nation (including North Dakota), the logistics and freight sector makes heavy use of double trailers for efficient transport. In North Dakota, several companies, including FedEx Freight and UPS, use double trailers for cross-border shipping to or from Canada. In this state, these two companies also use triples for parcel delivery. Retailers like Walmart and PepsiCo use double trailers to transport products to stores and warehouses. Marathon Petroleum uses double tanker trailers to transport crude oil. The agriculture sector uses doubles to transport bulk grain, livestock feed, flour, processed sugar, and fertilizer.

To legally pull doubles or triples, you must hold a Class A CDL, be qualified to operate air brakes, and obtain a Double/Triple (T) endorsement on the CDL. To get this endorsement, you must pass the Double/Triple knowledge test. This test covers such topics as safe handling, air brakes on doubles and triples, coupling and uncoupling, emergency situations, pre-trip inspections, and state and federal regulations on doubles and triples. (No special skills test is required for this endorsement.)

This knowledge test is based on the official North Dakota CDL manual (North Dakota CDL Handbook 2025), especially Chapter 7: Doubles and Triples. We can help you pass the knowledge test on your first try – something you can’t guarantee just by reading the manual.

This North Dakota Doubles and Triples Endorsement Practice Test, the first of five we offer, is based on the official CDL manual, just like the official Double/Triple knowledge test. It’s up to date as of April 2025. The 20 multiple-choice practice questions and answers on this practice test deal with air lines, converter dollies, coupling, emergency situations, following distance, and rearward amplification.

Our AI Assistant can give you a hint or further elaboration if you get stuck on a question or an immediate explanation of the correct answer if you still miss the question. You can also ask your own questions about driving.

This practice test isn’t timed; take all the time you want. Disappointed with your final score? You can retake this practice test as often as you wish.

Be sure to try our other four North Dakota Doubles and Triples Endorsement Practice Tests too!

Pass the first time with Premium
  • Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements

What you need to know

6 min to complete
Available in EN and ES
Verified by Steven Litvintchouk, M.S., Chief Educational Researcher, Member of ACES. See our detailed commitment to accuracy and quality in our practice tests.

What to expect on the actual ND DOT exam

20

questions

16

correct answers to pass

80%

passing score

List of questions (classic view)

  1. When you're pulling more than one trailer, which trailer should be the first one behind the tractor?
  2. Which of these statements about quick steering movements and doubles/triples is true?
  3. You are driving a 100-foot double trailer combination at 50 mph. The road is dry and visibility is good. You should keep at least ____ seconds of space ahead of you.
  4. Before connecting a converter dolly to a second or third trailer, you should check the height of the trailer. The trailer height is right if
  5. You are driving a 100-foot double trailer combination at 30 mph. The road is dry and visibility is good. You should keep at least ____ seconds of space ahead of you.
  6. With the hand valve on, you should test the trailer brakes by opening the service line valve at the rear of the rig. When you do this, you should hear
  7. Empty trucks
  8. Which of these statements about handling doubles and triples is true?
  9. Before you can supply air to the air tanks of a second trailer, you need to
  10. You are driving with double trailers and must use your brakes to avoid a crash. For emergency braking, you should
  11. How can you be sure that you supplied air to a second trailer?
  12. What is likely to happen if the pintle hook is unlocked while the dolly is still under the second trailer?
  13. You want to hook your combination to a second trailer that does not have spring brakes. To do this without wheel chocks, you should
  14. Which of these statements about managing space to the sides is true?
  15. The crack-the-whip effect that troubles trucks with trailers is most likely to tip over
  16. You are visually checking the coupling of a converter dolly to the rear trailer. How much space should there be between the upper and lower fifth wheel?
  17. You are pulling doubles. A set of trailer wheels goes into a skid. Which of the following is most likely to occur?
  18. You are doing a walk-around inspection of a double or triple trailer rig. You should be sure that the converter dolly air tank drain valves are ______ and the pintle hook is _______.
  19. A converter dolly is
  20. A converter dolly consists of a ______ wheel and ________ axles.
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