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Doubles and Triples Endorsement Practice Test 1

Last updated on May 5, 2023

Doubles and Triples Endorsement Practice Test 1 contains knowledge and safe driving information that all commercial drivers should know to successfully pass the CDL “Doubles and Triples Endorsement” written test.

CDL Doubles and Triples Endorsement Practice Test Methods:

Number of practice test questions with answers: 20

Number of correctly answered practice test questions needed to pass: 16

Passing score: 80%

This CDL Double/Triple Trailers Endorsement Practice Test #1 with Answers is applicable for all 50 States.

CDL Double/Triple Trailer Endorsement Practice Test (#1) With Answers



#1. Double and triple trailers are more likely to turn over than other combination vehicles, because:

#2. To check for air flow to the last trailer:

#3. It is dangerous to unlock the pintle hook with the converter dolly still under the rear trailer because:

#4. To uncouple double trailers, you should park your vehicle:

#5. When pulling triple trailers, always put the heaviest trailer:

#6. When connecting the converter dolly to the rear trailer, you should remember to:

#7. When inspecting doubles, the shut-off valves at the rear of the front trailer, rear of the last trailer, and the converter dolly, should be:

#8. When pulling triple trailers, which unit is the most likely to roll over:

#9. When coupling the rear trailer, the correct trailer height is:

#10. Converter dollies built on or after March 1, 1998, are required to have an antilock brake system (ABS).

#11. To position the converter dolly to couple a second trailer, you should release the converter dolly air brakes by:

#12. When uncoupling the converter dolly from a trailer, you should never unlock the ________ with the dolly still under the trailer.

#13. If the tractor protection valve does not work properly, this would:

#14. When making a visual check of the coupling of the rear trailer, how much space should there be between the upper and lower fifth wheel when the locking jaws are closed on the kingpin?

#15. What is the coupling device on a dolly with one or two axles and a fifth wheel called?

#16. The shut-off valve on the middle trailer of a set of triples should be:

#17. How do you know if your converter dolly is equipped with antilock brakes (ABS)?

#18. When testing the tractor protection valve, it should close (pop out) when the air pressure falls into what range?

#19. When steering to avoid a crash while pulling double or triple trailers, remember to:

#20. What is the first thing you should do when uncoupling a converter dolly?



The pool of questions used to produce this practice test have been independently created by CDL Digest and come directly from Code of Federal Regulations (Title 49 – Transportation) and the information provided in AAMVA’s “2005 CDL Test System (July 2010 or newer Version) Model Commercial Driver Manual”.

These are the same sources that all 50 State Driver Licensing Agencies (SDLA) are required to use by federal regulation (49 C.F.R. 383.133) to develop the pool of questions for all written tests needed for a person to obtain a commercial learner’s permit (CLP), commercial driver’s license (CDL), and/or any federally authorized endorsements.

Note: The above listed source information is static, meaning changes to the information used to create the pool of questions that your State Driver Licensing Agency (SDLA) uses for the actual written test have been extremely rare over the decades. Due to the static nature of the source information, you may see practice test questions and answers in this practice test that are very similar, if not identical to the questions and answers on the actual written test. If this occurs, it is purely coincidental. CDL Digest is not affiliated with the AAMVA or any government agency.


The source material used by CDL Digest to develop these practice test questions is very technical. Relying solely on the practice tests we have produced will not be enough to successfully pass the actual written tests. You will NEED to study in order to successfully pass these practice tests and the actual written tests.

CDL Double/Triple Trailer Endorsement Study Guide

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