DC CDL COMBINATION TEST - PRACTICE TEST

11. Hydroplaning:
never occurs at speeds below 40 mph.
only occurs at extremely high speeds.
only happens when tire pressure is higher than normal.
can occur at speeds as low as 30 mph.
12. What are the two basic reasons for covering cargo?
To protect the cargo from pilferage and from weather.
To protect the cargo from weather and to avoid littering.
To protect people from spilled cargo and the cargo from pilferage.
To protect people from spilled cargo and the cargo from weather.
13. To prevent rollover, you should:
keep the cargo as close to the ground as possible.
go slowly around turns.
drive slowly around on ramps and off ramps.
All of the above.
14. Which of the following statements about off-tracking is true?
If there is more than one trailer, the rear wheels of the last trailer will off-track the most.
When a vehicle goes around a corner, the rear wheels follow the same path as the front wheels.
Longer vehicles off-track less.
None of the above.
15. In vehicles with air brakes, the tractor protection valve:
provides the air pressure used to operate trailer brakes.
is used to connect the service and emergency air lines from the truck/tractor to the trailer.
keeps air in the tractor or truck brake system.
carries air, which is controlled by the trailer hand brake or the foot brake.
16. Inspecting the fifth-wheel does NOT include:
checking for missing or damaged parts.
making sure that the fifth wheel is in the proper position for coupling.
backing until the fifth-wheel just touches the trailer.
checking that there are no cracks in the frame.
17. Air brakes use ________ to make the brakes work.
compressed gas cylinders
compressed gases
compressed oil
compressed air
18. Cargo tie-downs are used to:
keep cargo from shifting or falling.
prevent skidding.
prevent freezing.
prevent right-turn accidents.
19. The center of gravity of a trailer should be:
as high as possible.
at the front of the trailer.
at the rear of the trailer.
as low as possible.
20. Loose cargo:
can be a danger to others and yourself.
could hurt or kill you during a quick stop.
could fall off your vehicle and cause traffic problems.
All of the above.
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