Improvements in or relating to roof bars for mines

摘要

892,861. Mine roof bars. COAL INDUSTRY (PATENTS) Ltd. July 14, 1958 [July 12, 1957], No. 22191/57. Class 20(2) [Also in Group XXV] In roof bars for mines engaging end to end by tongue and fork and connected by a swivel pin and a wedge 20, Fig. 10, the wedge has two curved surfaces Fig. 8 and the apertures 12, 13, Fig. 21, in the tongue, either of which is adapted to accommodate the wedge, have the same inclination and curvature so that the whole of that part of one of the curved surfaces of the wedge lying within the lug aperture engages the surface of the aperture. To install the bar 11, it is pivoted by the aperture 12 about the wedge 20, engaged in the aperture 16 of the fork of a bar 10 already in position, until the swivel pin can be inserted in holes 14, 18. The angle between the bars can be varied by inserting the wedge in holes 12, 16 or 13, 17 to a greater or less extent or by inverting one bar relatively to the other. The wedge may have a key 23 adapted to engage a key-way in either of the apertures, 16, 17 in the fork. The hinged pin has two curved surfaces with centres at 28, 29, Fig. 5, and is held captive by a locking plate engaging a flat 25 and may be tapered. The roof bar comprises two rolled steel joists welded together at the flanges.