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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!

Which of the following is NOT one of the steps involved in checking airflow to all trailers?
  • 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
  • Use the tractor parking brake and or chock the wheels to hold the vehicle
  • If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailer(s) and dolly are in the OPEN position
  • Wait for air pressure to reach normal, then push in the yellow "tractor air supply" knob
This is a question from page 59 - click here to look up the answer

Quote From Page 82 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.

Next
Which of the following shut off valve positions is incorrect?
  • All of these are correct
  • Converter dolly air tank drain valve: CLOSED
  • Rear of front trailers: OPEN
  • Rear of last trailer: CLOSED
This is a question from page 58 - click here to look up the answer

Quote From Page 83 Of The Illinois CDL Manual:

Double and triple trailers:

  • Shut-off valves (at rear of trailers, in service and emergency lines)
  • Rear of front trailers: OPEN
  • Rear of last trailer: CLOSED
  • Converter dolly air tank drain valve: CLOSED
  • Air lines supported and glad hands properly connected
  • If spare tire is on converter gear (dolly), make sure it is secured
  • Pintle-eye of dolly in place in pintle hook of trailer(s)
  • Pintle hook latched
  • Safety chains secured to trailer(s)
  • Light cords firmly in sockets on trailers
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Next
The shut-off valves on the middle trailer when pulling triple trailers should be in which position?
  • Both the service line and emergency line should be in the closed position
  • The service line should be closed but the emergency line should be open
  • The service line should be open but the emergency line should be closed
  • Both the service line and emergency line should be in the open 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:

Unless it is the very last trailer, all shut-off valves should remain in the open position so that all trailers have proper airflow in the air brake system.

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Next
Which of these steps for uncoupling the converter dolly is correct?
  • Disconnect safety chains
  • Lock the pintle hook on first semitrailer
  • Quickly pull clear of the dolly
  • Release converter gear spring brakes
This is a question from page 57 - click here to look up the answer

Quote From Page 81 Of The Illinois CDL Manual:

Uncouple converter dolly:

  • Lower dolly landing gear
  • Disconnect safety chains.
  • Apply converter gear spring brakes or chock wheels.
  • Release pintle hook on first semitrailer.
  • Slowly pull clear of dolly.
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Next
How do you check to make sure the trailer height is correct before coupling?
  • The trailer must be slightly lower than the center of the fifth wheel, so the trailer is raised slightly when dolly is pushed under.
  • The trailer should be a minimum of 1ft higher than the fifth wheel, so the trailer king pin will not strike the fifth wheel plate and cause damage
  • The trailer should be slightly higher than the center of the fifth wheel, so the trailer doesn't have to raise up when the dolly is pushed under
  • The trailer landing gear should be lowered completely so that you can push the dolly under the trailer and be ready to drive once attached
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.
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Next
When making a visual check of the coupling, all of the following inspections are correct, except:
  • Be certain the locking jaws are around shank and not the head of the kingpin
  • Check that there is no visible space between the upper and lower fifth wheel
  • Make sure there is enough grease
  • Ensure the release arm is properly seated and the safety latch is unlocked
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
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Next
When pulling two or more trailers, the shut off valves on the first trailer should be in the following positions:
  • The service line should be closed and the emergency line should be open
  • Both the service line and the emergency line should be open
  • Both the service line and the emergency line should be closed
  • The service line should be open and the emergency line should be closed
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:

Unless it is the very last trailer, all shut-off valves should remain in the open position so that all trailers have proper airflow in the air brake system.

Prev
Next
Which of the following is true about pulling double or triple trailers?
  • 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
  • Doubles/triples are less stable than other commercial 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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