CDL Class A Combination Vehicle Test
Questions With Verified Answers.
The trailer should be lowered so that...
A) the trailer is far above the fifth wheel
B) the tractor strikes the nose of the trailer
C) you can use the landing gear to make any adjustments
D) it's raised slightly when the tractor's backed under it - answer✔D
Which one of the following is controlled by the foot brake?
A) the service air line
B) the emergency air line
C) the shut off valve
D) the hose coupler - answer✔A
When you inspect the coupling, check to ensure that...
A) there's a little slack in the air lines
B) there's no slack in the air lines
C) the landing gear handle is hanging free
D) the electrical cable is unplugged - answer✔A
Air lines on a combination vehicle are often colored to keep them from getting mixed up. The
emergency line is ____; the service line is____.
A) Red, blue
B) Blue, red
C) Black, yellow
After you supply air to the trailer, make sure the air lines are not crossed and the trailer brakes
are working. This is done by:
A) applying and releasing the trailer brakes and listening for brake sounds
B) lifting the brake pedals
C) turning on the parking brakes from the cab
D) releasing the tractor brakes - answer✔A
You have coupled with a semi trailer. In what position should you put the front trailer supports
before driving away?
A) 3 turns off the top with the crank handle secured in it's bracket
B) fully raised with the crank handle secured in its bracket
C) raised 1/2 way with the crank handle removed
D) none of the above - answer✔B
You are coupling a tractor and semi trailer and have connected the air lines. Before backing
under the trailer, you should:
A) make sure that the trailer brakes are off
B) supply air to the trailer system, then pull out the air supply knob to lock the trailer brakes
C) apply the brakes twice to alert others
D) all of the above - answer✔B
When you get ready to back under the semi trailer you should line up:
A) about 12 degrees off the line of the trailer
B) the kingpin to engage the driver's side locking jaw first
C) exactly one trailer length in back of the trailer
D) directly in front of the trailer - answer✔D
You are coupling a tractor to a semi trailer and have backed up but are not under it. What should
you hook up before backing under?
A) the safety chain
B) the electrical service cable
C) nothing, back up and lock the fifth wheel
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