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

CDLCOMBINATIONVEHICLESTEST b b b




QUESTIONS WITH CORRECTANSWERS 2026 b b b b




How should you test the tractor semi trailer combination for being properly coupled? -
b b b b b b b b b b b b b




CORRECT ANSWER-
b b




Pull gently forward in low gear against the locked trailer brakes, then inspect your coupling.
b b b b b b b b b b b b b b




When coupling to the trailer, how far do you back up before stopping the first time? -
b b b b b b b b b b b b b b b b




CORRECT ANSWER-Until the fifth wheel plate just touches the trailer.
b b b b b b b b b b




What do you check before backing under the trailer? - CORRECT ANSWER-
b b b b b b b b b b b




Make sure the trailer brakes are set.
b b b b b b b




Air lines on a combination vehicle are often colored to keep them from getting mixed up. What
b b b b b b b b b b b b b b b b




color is the emergency line and what color is the service line? - CORRECT ANSWER- Red and
b b b b b b b b b b b b b b b b b




blue.
b




After you back up to the trailer and the fifth wheel plate touches the trailer, you set the tra ctor
b b b b b b b b b b b b b b b b b b b




park brake, get out and hook up the emergency and service air lines. Then what do yo u
b b b b b b b b b b b b b b b b b b




bdo before backing under the trailer? - CORRECT ANSWER-
b b b b b b b b




Supply air to the trailer system, then pull out the trailer air supply knob to fully set the
b b b b b b b b b b b b b b b b b




trai ler brakes.
b b b




What three things can you do to prevent rollovers? - CORRECT ANSWER-
b b b b b b b b b b b




Keep your load centered, keep the load as low in the trailer as possible, and go slow aroun
b b b b b b b b b b b b b b b b b




d turns.
b b




How far do you raise the landing gear on your trailer? - CORRECT ANSWER-
b b b b b b b b b b b b b




Crank it up as far as it will go.
b b b b b b b b b

, You have coupled with a semi trailer. In what position should you put the landing gear befo
b b b b b b b b b b b b b b b b




re driving away? - CORRECT ANSWER-
b b b b b b




Fully raised with the crank handle secured in its bracket.
b b b b b b b b b




When uncoupling, what could happen if you park the trailer at an angle? -
b b b b b b b b b b b b b




CORRECT ANSWER-You could do damage to the landing gear and dolly legs.
b b b b b b b b b b b b




Why should you lock the tractor glad hands together or couple them to the dummy glad ha
b b b b b b b b b b b b b b b b




nds when bobtailing? - CORRECT ANSWER-It will keep dirt and water out of the lines.
b b b b b b b b b b b b b b b




When backing under a trailer, you should expect the trailer to be lifted slightly by the fifth
b b b b b b b b b b b b b b b b




wheel plate. - CORRECT ANSWER-True.
b b b b b




Before you begin coupling, you should check your travel path for obstacles and hazards. -
b b b b b b b b b b b b b b




CORRECT ANSWER-True.
b b




What should your air supply pressure gauge read before backing under a trailer? -
b b b b b b b b b b b b b




CORRECT ANSWER-100 - 125 psi.
b b b b b




In case of a jackknife situation, you can use your trailer hand valve to apply trailer brakes t
b b b b b b b b b b b b b b b b b




o stop the trailer from skidding. - CORRECT ANSWER-False.
b b b b b b b b b




Which knob do you actuate to supply air to your trailer? - CORRECT ANSWER-
b b b b b b b b b b b b b




Push in on the tractor protection valve knob, which is the red knob.
b b b b b b b b b b b b b




Do combination vehicles take longer to stop when they are empty or loaded? -
b b b b b b b b b b b b b




CORRECT ANSWER-When they are empty.
b b b b b