Roof prop apparatus and method for longwall mining

Abstract

In longwall mining wherein a mine roof is normally supported by a succession of arches each in turn supported at one mine wall on a respective leg, a plurality of vertically expensible holders are pressed up against a plurality of respective adjacent arches with a common first beam, and legs of the thus-supported arches are removed so that the mine wall can be worked at this location. For advancing along the longwall all of the holders except the holder at one end of the row of holders are pressed upwardly against the respective arches with a second beam. The leg of the arch of the end holder is replaced and then the first beam is dropped down away from the row of holders. The end holder is then displaced to the opposite end of the row and the first beam is advanced toward this other end and the end holder is positioned under the arch immediately adjacent the other end. Then all of these holders including the end holder are pressed upwardly by the first beam against the respective arches and the second beam is dropped downward and displaced toward the other end. The leg of the newly supported arch can then be removed and the mine wall can be worked where this leg has been removed. Each of these beams is vertically displaceable relative to a lower beam by means of hydraulic cylinders and further hydraulic cylinders interconnect the lower beams for longitudinal stepping of the entire assembly.