A device for extending supply lines to winning machines in mining operations comprises a traction chain housing which includes a covered guide for a traction member such as an endless conveyor chain. The traction member rides in the housing and is preferably covered thereby both in respect to its upper and lower reaches. A supply line support bar is secured to the traction members at spaced locations along its length for movement therewith and has a forked support extending outwardly from the housing which has one leg portion defining a support over which the supply lines are laid and another leg portion covering the supply lines. The device may be made with an endless chain conveyor which has upper and lower reaches as well as a chain conveyor having side by side reaches and in each case the housing or a cover for the housing provides for the lateral extension of the forked portion of the supply line support bar.