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
E21D23/0056—Mine roof supports for step- by- step movement, e.g. in combination with provisions for shifting of conveyors, mining machines, or guides therefor with individual advancing shifting devices
Dispositif automatique a reglage millimetrique pour l'arret du coulissement relatif de deux elements, et appareillages mettant en oeuvre un tel dispositif