Manual Uncoupling

P4 DM Ch21; CasGen5 DM Ch20

  1. Apply the tractor and trailer parking brakes.
  2. Chock the trailer rear wheels.
  3. Lower the trailer landing gear until the weight is removed from the fifth wheel.
  4. Disconnect the tractor-to-trailer air system lines and electrical cable. Plug the air lines to prevent dirt or foreign material from entering the lines.
  5. Verify that both the yellow parking-brake and red trailer-air-supply knobs are out, the tractor and trailer parking brakes are set, and that the trailer is prepared for uncoupling.
  6. Release the kingpin locking mechanism following the instructions for each manufacturer below.
    1. Fontaine: Lift the safety latch and pull the lock control handle to the unlocked position. See Fig..

      Note: Make sure the safety latch is down when the control handle is locked.

      • The Fontaine locking mechanism in the unlocked position.

      • The Fontaine locking mechanism in the locked position.

      1. Safety Latch

      2. Lock Control Handle

      Fig. 1, Fontaine Locking Mechanism

    2. Holland: In the locked position the safety indicator swings freely over the operating rod. See Fig., View A.

      To unlock the mechanism, manually rotate the safety indicator toward the rear of the fifth wheel. See Fig., View B.

      Pull the operating rod out. When the upper operating rod shoulder is outside the slot, raise the handle and place the shoulder of the upper rod against the plate casting, above the slot. See Fig., View C.

      The fifth wheel is now in the lockset position and is ready for uncoupling. As the tractor pulls away from the trailer the kingpin forces the jaw to rotate, contacting the lock. Continued rotation of the jaw forces the lock to move outward, and drops the upper rod back into the slot. See Fig. View D. The wheel is now ready for coupling.

      • The Holland kingpin locking mechanism in the locked position.

      • The Holland kingpin locking mechanism in the Unlatched Position (the safety indicator rotated towards the rear of the fifth wheel).

      • The Holland kingpin locking mechanism in the Lockset Position (the upper rod resting against casting above slot).

      • The Holland kingpin locking mechanism in the Open Position (ready for recoupling).

      1. Safety Indicator

      2. Operating Rod

      3. Upper Rod

      4. Plate Casting

      Fig. 2, Holland Kingpin Locking Mechanism

    3. Jost: Pull the retractable handle out, then secure it in the open position with the catch. See Fig..

      • The Jost release handle is held open by catch a mechanism.

      Fig. 3, Jost Release Handle Unlocked

  7. Release the tractor parking brake then drive out slowly, allowing the trailer to slide down the fifth wheel and pick-up ramps.
Note:
Parent topic: Fifth Wheel Uncoupling
Document Number: 0000112047
Manual Publication Date: 2025-02-11
Topic Publication Date: 2025-03-07