GB684403A - Improvements in or relating to releasable supports for roofs in underground mines - Google Patents

Abstract

684,403. Mine chocks. MUSCHAMP, N. J., and COWLISHAW, F. July 21, 1950 [July 21, 1949]. No. 19197/49. Class 20 (ii) A mine chock 11 mounted by its inclined lower edge 13 on a support is held in operative position by a link 15 having lateral projections 19 on its end engaging in a notch 21 in the support and from which it is released by a lever 25 pivoted on the support and operated by a chain 33. The support shown in Fig. 1 comprises four chocks each one at a corner above an upright 1. The uprights are joined in pairs by plates 5 and a curved bearing plate 9, on which the chocks rest. The projections 19 engage in slots 23 in the inoperative position. In a modification, the cross bars 19 are replaced by rollers running on flanges of the members 5, 6. In Fig. 8, these rollers 41 have hooks 47 engaging hooks 51 on the levers 49, 50, which hold them in the operative position. The levers are operated to release the chocks by a chain 33 and link 53, which has a lost-motion slot connection 55 to the lever 50 so that the forward chock 12 is operated last, so that the planks 47 supported thereby are not moved. In a further modification, each chock is in two parts with a wedge driven between to allow for adjustment for height. The two parts of the wedge are connected by an extension on one passing through the wedge. Shallow steps are formed on the wedging surfaces to prevent the wedge being forced out by the weight of the roof.