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How to couple and uncouple a tractor-trailer as a CDL driver

A close up of a semi-truck's coupling system.

Estimated reading time: 5 minutes

Safely and efficiently coupling and uncoupling semi-trailers is a crucial element of working as a truck driver.

Whether you’re a new driver or have been driving for years, it’s always good to review the essential steps in the process. Keep reading for our all-encompassing guide on how to couple and uncouple a tractor-trailer.

How to couple a semi-trailer

The key to coupling a semi-trailer is being safe at all times and following the steps of the process in the right order. The easiest way to remember the process is to A.I.M.:

  • Align.
  • Inspect.
  • Make a secure couple.

Step 1: Align.

  1. Back up until the tractor’s rear drive wheels are just under the nose of the trailer and the fifth wheel is not touching the trailer.
  2. Set the brakes, put the truck in neutral, turn off the engine, remove the key from the ignition and safely exit the truck.
  3. Check the height of the trailer. Make sure the front edge of the trailer will contact the lower half of the tilted fifth wheel’s ramp area. Adjust the trailer’s height as needed.
  4. Make sure the trailer’s kingpin is in line with the center of the fifth-wheel opening. It must be less than two inches to the left or right of the center. Make sure there are no cracks or damage to the kingpin or trailer apron.
  5. Ensure the fifth-wheel opening is free of obstructions and the jaw is completely open.

Step 2: Inspect.

  1. Starting on the driver’s side of the truck, make sure:
  • The fifth wheel is securely mounted with no cracks or broken welds.
  • The pivot pin and cotter key are secure.
  • The slider pins are locked in place.
  • The slider stop blocks are secure.

2. Pull the handle all the way out and ensure it is:

  • Not bent.
  • The rear of the fifth wheel is fully tilted down.
  • The plate is well-greased.

3. Check the landing gear for:

  • Cracks.
  • Bends.
  • Broken parts.

4. Walk around the entire trailer and ensure:

  • The tandem release handle is pushed all the way in and down.
  • The slider locks are engaged.
  • The brake shoes are tight against the drums.
  • There are no obstacles above, below or around the trailer that would prevent it from coupling.

5. Inspect the fifth wheel from the passenger side and:

  • Ensure it is securely mounted with no cracks or broken welds.
  • Check the pivot pin and cotter key.
  • Look at the slider pins and slider stop blocks.
  • Make sure everything is locked in place and damage-free.

Step 3: Make a secure couple.

  1. Slowly back up until the fifth wheel picks up the nose of the trailer. Stop before the fifth wheel locks. For heavier loads, wait at least 60 seconds for tractor suspension to adjust.
  2. Once the trailer suspension adjusts, back up gently until the fifth wheel locks. Listen for a click or wait until you feel that the tractor will not back any further.
  3. After it locks, gently pull the tractor forward until you feel it tug on the kingpin without moving the trailer.
  4. Do this twice to ensure the kingpin is locked into the fifth wheel.
  5. Put the truck in neutral, set the brake, turn off the engine, take the key and exit the truck.
  6. Use a flashlight to check your connection. Make sure there is no gap between the trailer and the fifth wheel.
  7. Push the release handle and ensure it is properly positioned. Check to make sure the locking bar of the fifth-wheel jaw is fully across the kingpin and the lower flange of the kingpin is visible under the locking bar.
  8. Connect the air and electrical lines. There are three lines on the tractor – red, green and blue:
  • Grab the blue line by the glad hand and pull it down to release it from the coupler on the tractor.
  • Place the blue line’s glad hand at a 90° angle with the trailer’s blue coupler.
  • Slide the glad hand’s groove into the coupler to lock the line into place.
  • Grab the green line by the black plug and pull up to release it from the tractor’s socket.
  • Find the round, silver, flap-covered socket next to the blue-line connection on the trailer, lift the flap and push the green line’s plug into the socket.
  • Connect the red line’s glad hand to the trailer’s red coupler using the same steps as the blue line.

9. Crank up the landing gear and secure the handle.

A truck driver uncouples a trailer.

How to uncouple a semi-trailer

The acronym for uncoupling a trailer is D.R.O.P.:

  • Deliver.
  • Roll down first, then release.
  • Observe the uncoupling.
  • Pause.

Step 1: Deliver.

  1. Drive or back into position for uncoupling.
  2. Set the trailer brakes and back slightly to relieve the pressure between the fifth wheel-locking jaw and the kingpin.
  3. Set the tractor brakes, shut down the tractor, remove the key from the ignition and exit the tractor.
  4. Check the ground for uneven surfaces or soft areas. Make sure you have a solid surface for the landing gear to rest.

Step 2: Roll down first then release.

  1. Lower the landing gear until both pads are securely on the ground. There is no need for extra turns after that.
  2. Disconnect the air and electrical hoses. Secure them to the back of the cab.
  3. Pull the release handle on the fifth wheel. If the handle does not pull easily, back the tractor up a very small amount to release pressure on the jaws.

Step 3: Observe the uncoupling.

  1. Drive the truck slightly forward. Stop with the trailer still over the top of the tractor’s rear drive wheels.
  2. Make sure the trailer’s landing gear is holding the weight of the trailer.

Step 4: Pause.

  1. Wait at least 60 seconds before pulling away to prevent damage to the tractor.
  2. Make sure the airbags have deflated and you have good traction before driving off.

Please note this is an example of how to couple and uncouple. It is important to remember the type of driver you are, the company you work for and the type of truck you drive can impact how you couple and uncouple. Be sure to consult your company guidelines or speak with your leader for more information about coupling and uncoupling.

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