Three frame shield for steep seams - with frames advanced via interposed rails forming part of centre frame guide

摘要

Three frame shield support for steep seams in coal mines employes parallel guide linkages and shifting devices between the frames to connect them for the alternating advancing movements, each frame supplied with a caving shield between canopy and floor bar in the normal way. Guide rails (29) angling in the vertical plane only, are in the forward area of the centre frame (II) between this and the outer frame (I, III) so that the frames can be advanced relative to one another and adjusted in the vertical plane. The shields have sidewalls which can be extended to the side to provide guidance between the frames. The rails constitute the legs of a U frame (30) passed round the centre frame (II) arranged so that the forward stay (31) linking the legs at the front end can be pivoted on the floor bar (10) of the centre frame (II) round an axis which coincides with the longitudinal axis of the frame.