A coupling system for operably interconnecting an electrical system and a pneumatic system of a road tractor to a trailer when the road tractor and the trailer are connected together by a fifth wheel assembly and a kingpin to define a generally vertical pivot axis, the coupling system comprising: a track configured to be mounted to a frame of a road tractor; a connector support structure movably connected to the track for powered movement along a generally horizontal curved path; a connector assembly movably connected to the connector support structure for powered movement in a direction that is transverse to the curved path, the connector assembly including a first electrical connector that connects to an electrical system of a road tractor and a first pneumatic connector that connects to a pneumatic system of a road tractor; a second electrical connector electrically coupled to an electrical system of a trailer and a second pneumatic connector connected to a pneumatic brake system of a trailer; whereby, in use the one second electrical connector and second pneumatic connector are mounted to a trailer, and the coupling system is configured such that after connection of a trailer kingpin to a fifth wheel assembly, the connector support structure is movable from a first position along the curved path until the connector assembly is positioned in registry with the second electrical connector and second pneumatic connector, followed by movement of the connector assembly relative to the connector support structure to couple the first electrical and pneumatic connectors (38; 36) to the second electrical and pneumatic connectors (38A; 36A) whereby a tractor electrical and pneumatic system is operably coupled to a trailer electrical and pneumatic system, respectively, characterized in that the curved path comprises an arc defining a center at the vertical pivot axis of the kingpin. a track configured to be mounted to a frame of a road tractor; a connector support structure movably connected to the track for powered movement along a generally horizontal curved path; a connector assembly movably connected to the connector support structure for powered movement in a direction that is transverse to the curved path, the connector assembly including a first electrical connector that connects to an electrical system of a road tractor and a first pneumatic connector that connects to a pneumatic system of a road tractor; a second electrical connector electrically coupled to an electrical system of a trailer and a second pneumatic connector connected to a pneumatic brake system of a trailer; whereby, in use the one second electrical connector and second pneumatic connector are mounted to a trailer, and the coupling system is configured such that after connection of a trailer kingpin to a fifth wheel assembly, the connector support structure is movable from a first position along the curved path until the connector assembly is positioned in registry with the second electrical connector and second pneumatic connector, followed by movement of the connector assembly relative to the connector support structure to couple the first electrical and pneumatic connectors (38; 36) to the second electrical and pneumatic connectors (38A; 36A) whereby a tractor electrical and pneumatic system is operably coupled to a trailer electrical and pneumatic system, respectively, characterized in that the curved path comprises an arc defining a center at the vertical pivot axis of the kingpin.