Abstract: A fifth wheel coupling for coupling sections of a tractor-trailer articulated vehicle includes a main plate mounted on the tractor which defines a keyhole slot for receiving a kingpin mounted on the trailer. The keyhole slot terminates in a coupling aperture, and a locking mechanism movable between open and closed positions locks the kingpin in the aperture in the closed position to thereby couple the tractor and trailer together. A safety latch mounted in the keyhole slot is movable from an inactive position permitting the kingpin to move through the slot and into the aperture to an active position blocking the keyhole slot. An operating mechanism operates the locking mechanism and also moves the safety latch from the active to the inactive position to permit movement of the kingpin out of the keyhole slot when the tractor and trailer are uncoupled.

Abstract: A safety latch is mounted in the keyhole of a fifth wheel coupling for joining the sections of an articulated vehicle. The safety latch is movable from an inactive position permitting the kingpin to move through the slot and into the aperture to an active position blocking the keyhole slot thereby preventing movement of the kingpin through the keyhole slot when the sections are coupled together.