CDL Combination Vehicles Test 1 – Classic Mode

This is CDL Combination Vehicles Test 1 in our original Classic Mode. Simply click in your answer to each CDL practice test question. When you're finished, check your score and results. You can reset the test and retake it as needed.


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1. When uncoupling, it's a good practice to...

A couple the glad hands together
B couple the glad hands to dummy couplers
C hang the electrical cable with the plug end down
D all of the above are acceptable

2. If you cross your air lines on a new trailer with spring brakes...

A you won't be able to release the trailer brakes
B you won't be able to release the tractor brakes
C you won't have any operational brakes
D you'll have no way of knowing there's a problem

3. When traveling under 40 mph, you should follow other vehicles...

A Only during the day
B With a distance of one second for every ten feet of your vehicle length
C With a distance of one second for every twenty feet of your vehicle length
D As close as possible so others don't cut in

4. In order to supply air to the trailer, you must first...

A Push in the tractor protection valve.
B Pull out the "air supply' knob
C Stop engine so you can hear the brakes
D Cross the air lines to check for leaks

5. If one of the glad hands on your blue air line is missing a seal...

A take one off the red air line and use that as a temporary replacement
B you might end up with a service line air leak
C you could experience an emergency line air leak
D it's not a major problem and you should continue coupling

6. 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

7. The trailer hand valve should be used...

A Only at highway speeds
B Only when parking
C Only to test the trailer brakes
D Both B & C above

8. Which one of the following statements about tractor protection valves is NOT true?

A It keeps air in the tractor in the event the trailer air leaks
B It is controlled by the trailer air supply valve in the cab
C When it closes it allows air to leak from the tractor line
D It will close automatically if air pressure is low

9. You can damage the landing gear if you...

A back under the trailer at an angle
B align the tractor and trailer
C position the trailer kingpin in the center of the fifth wheel
D back under the trailer in a straight line

10. 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

End of Test #1

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