A self-advancing support for use on long-wall faces. One unit embodies three props. The front prop, which is attached to the face conveyor, carries two roof bars side by side that give cantilever support over the conveyor track. The two rear props are mounted on a common floor bar and carry a single roof bar that passes between the two front bars. The front prop is attached to the rear structure only by the advancing ram within the box structure of the floor bar.