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CDL Practice Test: Doubles And Triples

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CDL Practice Test: Doubles And Triples

Doubles And Triples Questions

Click On The Picture To Begin

Good Luck!

The following are proper steps to connecting the converter dolly to the front trailer, except:
  • Hook dolly to front trailer
  • Back first semi-trailer into position in front of dolly tongue
  • Secure converter gear support in the lowered position
  • Lock pintle hook
This is a question from page 56 - click here to look up the answer

Quote From Page 81 Of The Illinois CDL Manual:

Connect converter dolly to front trailer:

  • Back first semi-trailer into position in front of dolly tongue.
  • Hook dolly to front trailer.
  • Lock pintle hook.
  • Secure converter gear support in raised position
Next
Do converter dollies have spring brakes?
  • Converter dollies don't ever have spring brakes
  • Some converter dollies have spring brakes, but dollies are not required to have them
  • While some states don't require dollies to have spring brakes, it is required for dollies to have spring brakes on the interstate system
  • All converter dollies are required to have spring brakes if built after 1975
This is a question from page 56 - click here to look up the answer

Quote From Page 80 Of The Illinois CDL Manual:

A converter gear or dolly is a coupling device of one or two axles and a fifth wheel by which a semitrailer can be coupled to the rear of a tractor-trailer combination forming a double bottom rig.

  • Release dolly brakes by opening the air tank petcock. (Or, if the dolly has spring brakes, use the dolly parking brake control.
Prev
Next
Should the shut-off valves on the rear of the last trailer be open or closed?
  • Both the service line and emergency line should be in the closed position
  • Both the service line and emergency line should be in the open position
  • The service line should be open and the emergency line should be closed
  • The service line should be closed and the emergency line should be open
This is a question from page 59 - click here to look up the answer

Quote From Page 83 Of The Illinois CDL Manual:

Check air flow to all trailers: Use the tractor parking brake and or chock the wheels to hold the vehicle. Wait for air pressure to reach normal, then push in the red "trailer air supply" knob. This will supply air to the emergency (supply) lines. Use the trailer handbrake to provide air to the service line. 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 shut-off valves on the trailer(s) and dolly (5) are in the OPEN position. You MUST have air all the way to the back for all the brakes to work.

TruckingTruth's Advice:

All shut-off valves on the rear most trailer should always be in the closed position.

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Next
When pulling more than one trailer:
  • If there are three trailers, the heaviest should be in the middle
  • The heaviest trailer should be in first position behind the tractor
  • The position of the heaviest trailer is not important as long as the brakes are working properly
  • The heaviest trailer should be the very last trailer
This is a question from page 56 - click here to look up the answer

Quote From Page 80 Of The Illinois CDL Manual:

For the safest handling on the road, the more heavily loaded semi-trailer should be in first position behind the tractor. The lighter trailer should be in the rear.

Prev
Next
Which of these steps about uncoupling the rear trailer is incorrect?
  • Park in a "half circle" on firm level ground
  • Close air shut-offs at rear of first semitrailer (and on dolly if so equipped)
  • Release dolly brakes
  • Release converter dolly fifth wheel latch.
This is a question from page 57 - click here to look up the answer

Quote From Page 81 Of The Illinois CDL Manual:

Uncouple rear trailer:

  • Park in a straight line on firm level ground.
  • Apply parking brakes so rig will not move.
  • Chock wheels of second trailer if it does not have spring brakes.
  • Lower landing gear of second semitrailer enough to remove some weight from dolly.
  • Close air shut-offs at rear of first semitrailer (and on dolly if so equipped).
  • Disconnect all dolly air and electric lines and secure them.
  • Release dolly brakes.
  • Release converter dolly fifth wheel latch.
  • Slowly pull tractor, first semi-trailer and dolly forward to pull dolly out from under rear semi-trailer.
Prev
Next
Should you unlock the pintle hook with the dolly still under the rear trailer?
  • No, the dolly tow bar may fly up, possibly causing injury and making it very difficult to re-couple
  • None of these answers are correct
  • Yes, the pintle hook should always be unlocked while still under the rear trailer
  • Unlocking the pintle while under the rear trailer is a matter of personal choice
This is a question from page 57 - click here to look up the answer

Quote From Page 81 Of The Illinois CDL Manual:

Caution: Never unlock the pintle hook with the dolly still under the rear trailer. The dolly tow bar may fly up, possibly causing injury and making it very difficult to re-couple.

Prev
Next
When making a visual check of the coupling, all of the following inspections are correct, except:
  • Ensure the release arm is properly seated and the safety latch is unlocked
  • Be certain the locking jaws are around shank and not the head of the kingpin
  • Make sure there is enough grease
  • Check that there is no visible space between the upper and lower fifth wheel
This is a question from page 58 - click here to look up the answer

Quote From Page 82 Of The Illinois CDL Manual:

Check fifth wheel (lower)

  • Securely mounted to frame
  • No missing, damaged parts
  • Enough grease
  • No visible space between upper and lower fifth wheel
  • Locking jaws around shank, not head of kingpin
  • Release arm properly seated and safety latch/lock engaged

Check Fifth wheel (upper)

  • Glide plate securely mounted to trailer frame
  • Kingpin not damaged
Prev
Next
Which of these steps to connecting the converter dolly to the rear trailer is incorrect?
  • Back converter dolly under rear trailer
  • Close shut-off valves at rear of first trailer (and on dolly if so equipped)
  • Connect safety chains, air hoses and light cords
  • Make sure trailer brakes are locked and/or wheels chocked
This is a question from page 56 - click here to look up the answer

Quote From Page 81 Of The Illinois CDL Manual:

Connect converter dolly to rear trailer:

  • Make sure trailer brakes are locked and/or wheels chocked.
  • Make sure trailer height is correct. (It must be slightly lower than the center of the fifth wheel, so trailer is raised slightly when dolly is pushed under.)
  • Back converter dolly under rear trailer.
  • Raise landing gear slightly off ground to prevent damage if trailer moves.
  • Test coupling by pulling against pin of number two semi-trailer.
  • Make visual check of coupling. (No space between upper and lower fifth wheel. Locking jaws closed on kingpin.)
  • Connect safety chains, air hoses and light cords.
  • Close converter dolly air tank petcock and shut-off valves at rear of second trailer (service and emergency shut-offs).
  • Open shut-off valves at rear of first trailer (and on dolly if so equipped).
  • Raise landing gear completely.
  • Charge trailers (push "air supply" knob in) and check for air at rear of second trailer by opening the emergency line shut-off. If air pressure is not there, something is wrong and the brakes will not work.
Prev
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