E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
E21D23/00—Mine roof supports for step- by- step movement, e.g. in combination with provisions for shifting of conveyors, mining machines, or guides therefor
E21D23/0052—Mine roof supports for step- by- step movement, e.g. in combination with provisions for shifting of conveyors, mining machines, or guides therefor with advancing shifting devices connected therewith
E—FIXED CONSTRUCTIONS
E21—EARTH OR ROCK DRILLING; MINING
E21C—MINING OR QUARRYING
E21C29/00—Propulsion of machines for slitting or completely freeing the mineral from the seam
E21C29/04—Propulsion of machines for slitting or completely freeing the mineral from the seam by cable or chains
E21C29/06—Propulsion of machines for slitting or completely freeing the mineral from the seam by cable or chains anchored at one or both ends to the mine working face