GB625234A - Improvements in or relating to collapsible pit props - Google Patents

Abstract

625,234. Pit props. PARK GATE IRON & STEEL CO., Ltd., and COLCLOUGH, F. July 3, 1947, No. 17510. [Class 20(ii)] In a pit prop of the type in which a sliding head 1, Figs. 3, 4, rests on an inclined face 3 on the upper end of the main length 2 of the prop, the sliding head 1 is connected to the main length 2 by links 19 pivoted at 7, 20, and is provided with a pivoted catch 8, 9 embracing the sliding head 1 and which, in the locked position of the prop, bears on the side of the main length 2 intersected by the upper end of the inclined face 3, the catch 8, 9 being movable about its pivot 7 to pass above and to clear the upper end of the inclined face 3 when the prop is to be collapsed. As shown both the head 1 and main length 2 are formed of H-section and the catch comprises links 8 pivoted on a bar 7 and extending horizontally to carry a roller 9 which bears on a plate 10 welded across the flanges of the main length 2. A rotatable spring hook 12 extending through a hole 13 in the plate 10 serves to hold the roller 9 against accidental movement. A catch release device consists of two cam plates 28, spaced by a connecting bar 29, the plates 28 embracing the flanges of the main length 2 and being secured to them by means of a removable pivot pin 27 so that the upper edges 30 of the plates 28 lie just below the two links 8 carrying the ends of the catch roller 9. The outer face of the upper part of the plate 10 may be curved to ease the passage of the roller 9 .to the edge 31. The cam plates 28, bar 29 and the pivot 27 may be fixed permanently to the prop or alternatively may be applied only when the prop is to be collapsed, in which case they may be used for releasing any number of props of one particular width of section.