A device for transferring a line between a retracted state and an extended state includes a line arranged in an interface region between a semitrailer train and a semitrailer, wherein the line has a first line section and a second line section and wherein the line is longer in the extended state than in the retracted state, and an envelope element via which the first line section and the second line section are connectable for transfer between the retracted state and the extended state by forming a telescopic mechanism.