Abstract: A longwall mining system includes a bidirectional shearer and a roof supporting structure. The shearer includes a pair of angled floor drums, a pivotable roof drum and a loading conveyor. Each drum has a plurality of picks disposed about the drum surface for cutting a material to be mined and a plurality of vanes disposed on the drum surface for carrying the cut material to the loading conveyor. The roof supporting structure includes a load carrying shield which is braced by a pair of supports. The supports are located under the shield in a position between the shearer and a face conveyor. The face conveyor, which is fed by the loading conveyor, carries the mined material to main conveyor for haulage to the outside.

Abstract: A chainless haulage system having at least three pairs of sprocket wheels, each pair disposed on a separate axle with opposed wheels on each axle aligned in a pair of parallel planes. Two pairs of sprocket wheels are disposed laterally offset from each other and serve as follower sprocket wheels, while a third pair is driven by conventional means. A pair of endless drive chains each having adjacent chain links in generally perpendicular planes respectively engage sprocket wheels disposed in the parallel planes to form a double strand of drive chain. The two endless drive chains are interconnected by a plurality of crossbars, each of which is formed of a pair of opposed chain links integrally connected by a connecting bar, the chain links of the cross bar inserted in series with the links of the endless drive chain. A hollow cylindrical roller is loosely disposed around the connecting bar of the cross bar.