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CDL Practice Test: Doubles And Triples

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CDL Practice Test: Doubles And Triples

Doubles And Triples Questions

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Good Luck!

Why do you need to manage your space better while pulling doubles/triples?
  • All of these answers are correct
  • Doubles / triples take up more space in turns
  • Doubles / triples tend to be blown around more during windy conditions
  • Doubles / triples require more stopping distance to avoid a jackknife
This is a question from page 55 - click here to look up the answer

Quote From Page 80 Of The Illinois CDL Manual:

Doubles and triples take up more space than other commercial vehicles. They are not only longer, but also need more space because they cannot be turned or stopped suddenly. Allow more following distance. Make sure you have large enough gaps before entering or crossing traffic. Be sure you are clear at the sides before changing lanes.

Next
Which of the following is true about pulling double or triple trailers?
  • Doubles/triples are less stable than other commercial vehicles
  • Doubles/triples don't jackknife as easily as single trailer vehicles
  • Doubles/triples are less prone to rollovers than single trailer vehicles
  • Doubles/triples are easier to handle in windy conditions than single trailer vehicles
This is a question from page 55 - click here to look up the answer

Quote From Page 80 Of The Illinois CDL Manual:

Take special care when pulling two and three trailers. There are more things that can go wrong, and doubles/triples are less stable than other commercial vehicles. Some areas of concern are discussed below.

TruckingTruth's Advice:

Pulling doubles or triples are much more dangerous in nearly every aspect of driving, which is why they require an additional endorsement. Be extra cautious when driving a truck with two or more trailers.

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Should you unlock the pintle hook with the dolly still under the rear trailer?
  • None of these answers are correct
  • Yes, the pintle hook should always be unlocked while still under the rear trailer
  • No, the dolly tow bar may fly up, possibly causing injury and making it very difficult to re-couple
  • 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.

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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 open position
  • The service line should be closed and the emergency line should be open
  • The service line should be open and the emergency line should be closed
  • Both the service line and emergency line should be in the closed position
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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When pulling more than one trailer:
  • 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
  • The heaviest trailer should be in first position behind the tractor
  • If there are three trailers, the heaviest should be in the middle
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.

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When pulling 3 trailers, the lightest trailer should:
  • Be the middle trailer
  • Be the first trailer
  • The placement of the lightest trailer doesn't matter
  • Be the 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.

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Should you pull a dolly out from under a trailer before you disconnect it from the trailer in front?
  • Yes, that way you can use the truck and first trailer to pull the dolly away from the rear trailer
  • Removing the dolly before disconnecting is simply personal preference and it doesn't matter much either way
  • No, the dolly should be removed after all trailers have been dropped to avoid damaging the trailer or dolly
  • No, you should never leave the rear trailer without a dolly attached to it
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.
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Next
All of the following are correct steps to positioning the converter dolly in front of the second (rear) trailer except:
  • Wheel dolly into position in front of second trailer in line with the kingpin
  • Move the dolly to rear of first trailer and couple it to the trailer
  • Pull dolly into position as close as possible to nose of the second semitrailer
  • Be sure the pintle hook is unlocked
This is a question from page 56 - click here to look up the answer

Quote From Page 80 Of The Illinois CDL Manual:

Position converter dolly in front of second (rear) trailer:

  • Release dolly brakes by opening the air tank petcock. (Or, if the dolly has spring brakes, use the dolly parking brake control.)
  • If the distance is not too great, wheel dolly into position by hand so it is in line with the kingpin.
  • Or, use the tractor and first semitrailer to pick up the converter dolly:
  • Position combination as close as possible to converter dolly.
  • Move dolly to rear of first semi-trailer and couple it to the trailer.
  • Lock pintle hook.
  • Secure dolly support in raised position.
  • Pull dolly into position as close as possible to nose of the second semitrailer.
  • Lower dolly support.
  • Unhook dolly from first trailer.
  • Wheel dolly into position in front of second trailer in line with the kingpin
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Finish
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