Cdl Combination Vehicles Test

Front 1

1. Which shut-off valves should be open and which closed?

Back 1

The front trailers shutoff valves open and the rear closed.

Front 2

2. Combination vehicles are usually lighter, shorter, and require less driving skill than single commercial vehicles.

Back 2

False.

Front 3

3. Fully loaded rigs are ten times more likely to roll over in a crash than empty rigs.

Back 3

True.

Front 4

4. What is the emergency air line for?

Back 4

It supplies air to the trailer air tanks and controls the emergency brakes on combination vehicles.

Front 5

5. Combination vehicles are usually lighter, shorter, and require less driving skill than single commercial vehicles.

Back 5

False.

Front 6

6. Trailers will have red ABS malfunction lamps on the left side, either on the front or rear corner.

Back 6

False.

Front 7

7. What two things are most important to prevent a rollover?

Back 7

Keeping the cargo as close to the ground as possible and driving slowly around turns.

Front 8

8. Large combination vehicles take longer to stop when they are empty than when they are fully loaded.

Back 8

True.

Front 9

9. Combination vehicles and the rearward amplification each trailer has after a quick lane change is referred to as what?

Back 9

Crack the whip effect.

Front 10

10. What is off tracking?

Back 10

Off tracking is when the rear wheels follow a different path than the front wheels.

Front 11

11. Using dummy couplers will prevent water and dirt from getting into the coupler and the airlines when not in use.

Back 11

True.

Front 12

12. The trailer hand valve should be used only to test the trailer brakes.

Back 12

True.

Front 13

13. After coupling, how much space should be between the upper and lower fifth wheel?

Back 13

None.

Front 14

14. Charge the trailer air brake system and check that the trailer rolls freely. Then stop and pull out the trailer air supply control valve. Pull gently on the trailer with the tractor to check that the trailer emergency brakes are on.

Back 14

This is how can you test the trailer emergency brakes.

Front 15

15. Red colored glad hands are used for the service air lines.

Back 15

False.

Front 16

16. Charge the trailer air brake system and push the air supply knob in. Shut the engine off. Step on and off the brake pedal several times to reduce the air pressure in the tanks. The trailer air supply control should pop out when the air pressure falls into the pressure range specified by the manufacturer.

Back 16

This is how can you test the tractor protection valve.

Front 17

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

Back 17

It may not couple correctly.

Front 18

18. Glad hands are coupling devices used to connect the service and emergency air lines from the truck or tractor to the trailer.

Back 18

True.

Front 19

19. Blue colored glad hands are used for the emergency air lines.

Back 19

False.

Front 20

20 . When you turn suddenly while pulling double trailers, which trailer is most likely to turn over?

Back 20

The rear trailer.

Front 21

21 .Which of the following best describes what the trailer air supply control does.

Back 21

You push it in to supply the trailer with air, and pull it out to shut the air off and put on the trailer emergency brakes.

Front 22

22. Check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and apply trailer brake with the hand control trolley valve, if so equipped.

Back 22

This is how can you test the trailer service brakes.

Front 23

23. What is the first thing you should do in an attempt to recover from a trailer skid?

Back 23

Stop using the brake.

Front 24

24. Where are shut-off valves?

Back 24

At the back of each trailer.

Front 25

25. Describe what the service line is for.

Back 25

It carries air which is controlled by the foot brake or the trailer handbrake. It carries air which is controlled by the foot brake. It carries air which is controlled by the the trailer handbrake. All of the above.

Front 26

26. Why should you never use the trailer handbrake to straighten out a jackknifing trailer?

Back 26

The trailer wheels. caused the skid in the first place. Once the trailer wheels grip the road again, the trailer will start to follow the tractor and straighten out.

Front 27

27. What is best and fastest way to recognize that the trailer has started to skid?

Back 27

Seeing it in your mirrors.

Front 28

28. You should look into the back of the fifth wheel to see if it is locked onto the kingpin.

Back 28

True.

Front 29

29. Why should you never use the trailer hand valve while driving?

Back 29

It should not be used in driving because of the danger of making the trailer skid.

Front 30

30. A trailer jackknife is more likely to happen if the trailer is loaded or empty?

Back 30

Empty.

Front 31

31. Why should you use tire chocks when parking a trailer without spring brakes?

Back 31

If the air supply in the trailer air tank has leaked away there will be no emergency brakes enabling the trailer wheels to turn freely.

Front 32

32. When the wheels of a trailer lock up, the trailer will tend to swing around.

Back 32

True.

Front 33

33. Go to the rear of the rig. Open the emergency line shut-off valve at the rear of the last trailer. You should hear air escaping, showing the entire system is charged. Close the emergency line valve. Open the service line valve to check that service pressure goes through all the trailers (this test assumes that the trailer handbrake or the service brake pedal is on), then close the valve. If you do NOT hear air escaping from both lines, check that the shutoff valves on the trailer(s) and dolly(s) are in the OPEN position.

Back 33

This is how can you test that air flows to all trailers.

Front 34

34. More than half of truck driver deaths in accidents are the result of truck rollovers.

Back 34

True.