A system for connecting supply lines between a tractive vehicle and a semi-trailer that can be coupled to the latter, a semi-trailer coupling and an automatic line coupling system comprising at least one connector jack being situated on the tractive vehicle and the semi-trailer having at least one supply circuit comprising a first supply console for connecting to the tractive vehicle and for receiving a plug-in element that is located on at least one supply line of the tractive vehicle and/or a plug that is configured to fit the connector jack. The aim of the invention is to provide a system for connecting supply lines for tractive vehicles, comprising an automatic line coupling system that permits the coupling of conventional semi-trailers. To achieve this, a second supply console is located on the tractive vehicle and is permanently connected to the connector jack of the line coupling system and the plug-in element can be selectively connected to the first or second supply console.