GB1044907A - Improvements in or relating to mine roof supports - Google Patents

Abstract

1,044,907. Mine roof supports. ELECTROHYDRAULICS Ltd. Sept. 14, 1964 [Aug. 8, 1963], No. 31435/63. Heading E1E. In a mine roof support 2, 3 or 4 (Fig. I) comprising two support frames which are guided for relative longitudinal sliding movement, at least one frame has a bowed guide 6 (Fig. 2) which is convex in the direction of the downward gradient (shown by the arrow) when the roof support is used in a sloping seam to counteract the tendency of the support to head down the slope upon advance. The guide is bowed so that the included angle 0 between the tangent to its neutral axis, at its rear end, and the longitudinal axis of the support, is equal to the angle through which a frame can turn due to the tolerances between the guide connecting means 5 and the guide 6. Both frames may have a bowed guide 6 the convexities of which face in the said direction, the said angle # for each guide being then equal to half the angle through which a frame can turn due to the said tolerances to give the same result. With a level seam the guides 6 of a support are convex in opposite directions to obtain the desired movement. To compensate for wear of the bearing of the guide connecting means 5, the guide(s) is or are bowed to compensate for the tolerances and the wear, and it is/they are initially inclined to the mine floor in the plane of the bowing to compensate for the bowing only, and then less so to compensate for wear also as it occurs.