Abstract: A pneumatic connector arrangement for a horse and trailer includes a piston (16) movable within a housing (12) to engage the base of the trailer kingpin (22) which is modified to include discrete passages (40, 42) for conveying permanent air supply and service line air to the trailer pneumatic system. The piston (16) has similar discrete passages (18, 20) which link to the kingpin passages upon link-up of the horse and trailer. The air supplies enter the piston passages by way of ports (30, 32).