Press "Enter" to skip to content

Combination Vehicles Practice Test 2

Last updated on May 5, 2023

Combination Vehicles Practice Test 2 contains knowledge and safe driving information that all commercial drivers should know to successfully pass the CLP/CDL “Combination Vehicles” written test.

CDL Combination Vehicles Practice Test 2 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 Combination Vehicles Practice Test #2 with Answers is applicable for all 50 States.

Combination Vehicles Practice Test 1

CDL Combination Vehicles Practice Test (#2) With Answers:



#1. The trailer brakes should be tested with ________ but controlled in normal operation with the foot pedal.

#2. The _________ are used to close the air-lines off when another trailer is not being towed in the combination.

#3. What might happen if the trailer is too high when you try to couple?

#4. When driving a combination vehicle, as soon as you see the trailer drifting off the proper path, you correct the drift by:

#5. After coupling a tractor to a semi-trailer, to lock the trailer brakes (Step 9), you can pull out the “air supply” knob or move the tractor protection valve control lever from the “_________” position to the “emergency” position.

#6. If you look in the mirrors while driving and notice a trailer skid, you should:

#7. When parking a combination vehicle, if the trailer does not have spring brakes, use _________ to keep the trailer from moving.

#8. Failure to keep the fifth wheel plate ________ could cause steering problems because of the friction between the tractor and trailer.

#9. When inspecting the upper fifth wheel, you must make sure the king pin is not damaged and the ________ is securely mounted to the frame.

#10. When uncoupling the tractor from the semi-trailer, Step 1 is positioning the tractor and semi-trailer, Step 2 is easing pressure on the king pin locking jaws, Step 3 is:

#11. When positioning the tractor (Step 3) to couple it to a semi-trailer, you should never back under the trailer at an angle, because:

#12. When only the trailer has antilock brakes (ABS), the trailer is _________ to swing out during hard braking.

#13. When the wheels of the trailer lock up, the trailer will begin to skid (“trailer jackknife”), this is more likely to happen when the trailer is:

#14. To check that air is flowing to all trailers, which shut-off valves should be open and which should be closed?

#15. If for any reason, while driving a combination vehicle, you get stuck on the tracks at a railroad-highway crossing, you should:

#16. If you have a trailer manufactured before antilock brake systems (ABS) were required (before March 1, 1998), how can you tell if the trailer is equipped with antilock brakes (ABS)?

#17. Converter dollies (built before 1975) that do not have spring brakes, have emergency brakes, which work from the:

#18. When coupling a tractor to a semi-trailer, what is Step 12 in the process?

#19. Some vehicles have _________ that the air hoses may be attached when they are not in use.

#20. Each trailer and converter dolly have one or more air tanks. They are filled by the ________.


CDL Combination Vehicles Practice Test #1


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.

Class “A” Commercial Learner’s Permit Study Guide

Class “B” Commercial Learner’s Permit Study Guide

Complete CDL Study Guide

CDL Combination Vehicles Study Guide

You Tube: [Direct Link]

Rumble: [Direct Link]