Improvements in collapsable mine props, mine chocks and the like

摘要

536,991. Mine-roof supports. WILSON, J. Feb. 23, 1940, No. 3419. [Class 20 (ii)] A collapsable mine prop or chock comprises an upper tubular member 10 with an end wall 16 toothed on its lower surface, a lower tubular member 11 with a plug 13 toothed in its upper face to coact with the toothed wall, a sleeve 12 surrounding the coacting toothed faces and pinned to the lower tubular member, a headed key 18 passing through a slot 17 in the end wall 16 which has an enlargement 17SP1/SP at one end adapted to receive the enlarged head of the key, and opposed slots 19, 20 in the sleeve to receive the key, one of these slots 19 being of inverted angle formation. A shackle pin 21 is pinned to the end of the key to retain the key in the slot 17 and to provide attachment for a hauling rope. Specifications 292,036, [Class 20 (ii)] and 427,981 are referred to.