CDL Combination Vehicles Questions with Correct Answers 2026 | Complete Study Guide & Practice Test

CDLCOMBINATIONVEHICLESQUESTIONS b b b




WITH CORRECT ANSWERS 2026 b b b b b




When should you use the hand valve to park a combination vehicle? - CORRECT ANSWER-
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never
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Which answer is correct for the air valves when testing the trailer service brakes only? -
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CORRECT ANSWER-
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Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolly: applied
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You are coupling a semi trailer to your tractor but have not yet backed under. The trailer is
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at the right height when: - CORRECT ANSWER-
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It will be raised slightly when the tractor is backed under it.
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How should you test the tractor trailer connection for security? - CORRECT ANSWER-
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Pull gently forward in low gear against the locked trailer brakes, then inspect the coupling
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Which answer is correct for the air valves when testing the trailer spring/parking brakes onl
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y? - CORRECT ANSWER-
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Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolly: released
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Your emergency air line breaks or gets pulled apart while you are driving. The loss of press
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ure will cause the: - CORRECT ANSWER-Emergency trailer brakes to come on
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You supply air to the trailer tanks by: - CORRECT ANSWER-
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Pushing in the trailer air supply valve.
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There are two things that a driver can do to prevent a roll over. They are: (1) keep the carg
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o as close to the ground as possible; and (2): - CORRECT ANSWER-Go slowly around
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bturns.

, You are coupling a semi trailer to your tractor but have not yet backed under. The trailer is
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at the right height when: - CORRECT ANSWER-
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It will be raised slightly when the tractor is backed under it.
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The fifth wheel locking lever is not locked after the jaws close around the kingpin; this mea
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n: - CORRECT ANSWER-
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The coupling is not right and should be fixed before driving the coupled unit
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When backing your tractor under a trailer, you should expect: - CORRECT ANSWER-
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Trailer will be lifted slightly when the tractor backs under it.
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Before you start to uncouple, you must - CORRECT ANSWER-
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Make sure the ground is solid and can support the weight of the trailer
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During uncoupling, you should disconnect electrical cable and - CORRECT ANSWER-
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Hang it with the plug down
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As part of your vehicle in inspection test, if your vehicle is equipped with air brakes and ha
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s a trailer, you will inspect the air connections between the truck or tractor and the trailer. Make
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sure that the
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CORRECT ANSWER-Glad hands b b




If your vehicle gets stuck on a railroad track, you should - CORRECT ANSWER-
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Get away from your vehicle and call 911 or the posted emergency
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If your test of the tractor protection valve is successful, - CORRECT ANSWER-
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The tractor protection valve control (trailer air supply control) will pop out or go from "nor mal"
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bto "emergency" b