Coupling/Uncoupling and Weight Transfers

Coupling Procedure

1. Survey the Tractor: Examine your tractor's design to find the specific area intended to make contact with the trailer during coupling: the "contact point".

2. Adjust Trailer Height: Lower the trailer's height to the height of the "contact point" for the tractor-a point on the tractor that would allow the tractor to lift the trailer upon contact when put in reverse, relieving the landing gear from the weight of the trailer.

3. Couple Trailer: Reverse slowly to connect tractor with trailer.

4. Facilitate Tug Test: Perform two gentle tug tests to verify the coupling is secure.

5. Raise Landing Gear: Raise the landing gear completely.

6. Connect Airlines and Pigtail: Connect blue and red airlines, and pigtail

Uncoupling Procedure

1. Lower the Trailer Landing Gear: Lower the landing gear until it makes contact with the ground, slightly lifting the trailer. This will relieve pressure on the fifth wheel, allowing the release handle to be pulled out fully.

2. Pull 5th Wheel Handle to Unlock Kingpin

3. Raise the Landing Gear: Once the release handle is disengaged, raise the landing gear, leaving only a few inches between it and the ground.

4. Disconnect Airlines and Pigtail: Disconnect the blue and red airlines and pigtail from the trailer.

5. Lower Trailer Suspension: Inside the tractor, use the suspension dump valve to release air from the airbags. Continue dumping air for approximately 15 seconds until you hear a click from the fifth wheel, indicating complete air release.

6. Release Trailer: Slowly pull away from the trailer, stopping immediately after release to provide a safety catch in case of landing gear failure. 

1. Verify 5th Wheel is Locked: When sliding the fifth wheel, make sure  the fifth wheel is securely locked around kingpin of trailer. 

2. Lower trailer landing gears: Observe carefully; stop when the landing gears touch the ground. 

3. Switch to the slow gear of the landing gear crank handle: Raise the trailer until the weight of the trailer is fully released off off the tractor drive axles, and so that only a very very small sliver of light can be seen between the top of the fifth wheel and bottom of trailer. The idea is to adjust the trailer height just high enough that the weight of the trailer is released off of the 5th wheel; the 5th wheel slide gears are able to unlock, allowing the 5th wheel to move. 

4. Inside the cab with the engine running and foot on the brake, engage the 5th Wheel slide so that the 5th Wheel gears unlock. 

5. When the gears unlock, release the tractor brakes only. 

6. Slowly creep forward or in reverse, depending on which way you want the 5th wheel to slide. 

   1. Keep in mind the 5th wheel's notches are very close together. For each 5th wheel notch, the driver must be very gentle on the throttle so as to move the wheels only a couple of inches, forward or reverse. 

7. When desired position is reached, stop. Disengage 5th Wheel slide so that gears lock back into place.

*A good rule of thumb for estimating weight transfer using the 5th wheel slide is 250lbs per notch (this will vary depending on make and model of the vehicle).