Fontaine and Holland Fifth Wheels Coupling

P4 DM Ch21; CasGen5 DM Ch20

Fifth wheel coupling is activated with the lock control handle located on either the right side or left side of the fifth wheel. Coupling has successfully occurred when the kingpin has been forced into the jaws and the lock control handle has moved to the locked position.

Notice: Some fifth wheels may be mounted on sliding rails. Before attempting to couple a trailer to a sliding fifth wheel, the slide feature must be locked to prevent the top plate from sliding rapidly forward or rearward, causing damage to the fifth wheel or kingpin.

  1. Chock the front and rear of the trailer tires to prevent the trailer from moving.
  2. Ensure the fifth wheel jaw is fully open and the operating rod is in the unlocked position. See Fig. or Fig..

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

    • Unlocked

    • Locked

    1. Safety Latch

    2. Lock Control Handle

    Fig. 1, Fontaine Locking Mechanism

    1. Safety Latch

    2. Operating Rod (locked)

    3. Operating Rod (unlocked)

    Fig. 2, Holland Simplex SE Locking Mechanism

  3. Make sure the fifth wheel top plate is tilted so the ramps are as low as possible.
  4. Position the tractor so that the center of the fifth wheel is in line with the trailer kingpin. The kingpin should be in a position to enter the throat of the locking mechanism.

    5. Notice: Attempting to couple at the wrong height may cause improper coupling, which could result in damage to the fifth wheel or kingpin.

  5. Adjust the trailer height if required.

    For a standard fifth wheel plate, the trailer should contact the fifth wheel approximately 4 to 8 inches (10 to 20 cm) behind the fifth wheel pivot. See Fig..

    For a low-lube fifth wheel plate, the fifth wheel must slide freely under the trailer, and the trailer should contact the fifth wheel at the pivot. See Fig..

    A proper connection for a standard fifth wheel trailer is ensured by ALL of the following:

    • The fifth wheel is lifting the trailer.

    • The trailer height is adjusted with the crank.

    • The ramps are tilted down.

    • The trailer is connected 4 to 8 inches behind the fifth wheel pivot.

    Fig. 3, Trailer Connection Point, Standard Fifth Wheel

    A proper connection for a low-lube fifth wheel trailer is ensured by both of the following:

    • The trailer height is adjusted with the crank.

    • The ramps are tilted down.

    Fig. 4, Trailer Connection Point, Low-Lube Fifth Wheel

  6. With the fifth wheel lock opening aligned with the trailer kingpin, back the tractor slowly toward the trailer. After sliding under the trailer, STOP to prevent from hitting the kingpin too hard, then resume backing slowly until the fifth wheel locks.

    On a standard fifth wheel, the fifth wheel must lift the trailer.

    On a low-lube fifth wheel, do not lift the trailer as this may damage the fifth wheel plate.

  7. Apply the tractor parking brakes.

    8. Warning: A visual inspection is required by law. Some improper couplings can pass a pull test. Sound is not reliable. Get out of the cab and look. Incorrect coupling could cause the trailer to disconnect, possibly resulting in serious personal injury or death.

  8. Perform a coupling inspection, checking that there is no gap between the bottom of the trailer and the fifth wheel, and that the kingpin is securely locked. See Fig..

    When lockup has occurred, the fifth wheel control handle moves to the locked position. Make sure that the safety latch is down over the lock control handle to hold the control handle in the locked position. (The safety latch will only rotate down if the operating rod is fully retracted in the locked position.) See Fig. for Fontaine fifth wheels. See Fig. for Holland fifth wheels.

    A successful inspection of the trailer coupling requires both of the following:

    • There is no gap between the trailer and fifth wheel.

    • The kingpin is securely locked.

    Fig. 5, Coupling Inspection

  9. Release the tractor parking brakes. Test for kingpin lockup slowly inching the tractor forward, pulling on the trailer against the chocks.
  10. After lockup is completed, connect the tractor-to-trailer air system lines and the electrical cable to the trailer. Take care to prevent dirt or foreign material from entering the air system lines.

    11. Notice: Always make sure the connection hanger keeps the trailer air hoses and electrical cables positioned so that they do not rub on anything. Rubbing may wear through hoses or cables, resulting in air leaks, or exposed or broken wires, potentially affecting trailer brake or electrical systems.

  11. Charge the air brake system with air, checking that the air connections do not leak.

    12. Warning: Incorrect fifth wheel lock adjustment could cause the trailer to disconnect, possibly resulting in serious personal injury or death.

  12. With the trailer wheels chocked and the brakes set, check for clearance between the kingpin and the fifth wheel jaws by moving the tractor forward and backward against the locked kingpin. If slack is present, uncouple the trailer and have the fifth wheel inspected and adjusted by a certified technician.
Note:
Parent topic: Fifth Wheel Coupling
Document Number: 0000112142
Manual Publication Date: 2025-02-11
Topic Publication Date: 2025-03-07