Kingpin Tug

An informal name for the pusher tug of an articulated tug-barge (ATB), referring to the kingpin or coupling pin that links the two hulls. In an ATB the tug’s bow notches into a stern recess in the barge, and a mechanical coupling (for example Intercon or JAK Articouple) drives pins from the tug’s hull into vertical racks or pads in the notch, leaving the tug free to pitch but locked in yaw and surge. The pin coupling, not a hawser, transmits thrust, so the unit pushes like a single ship while remaining a tug and barge in law.