| 摘要 |
1,166,578. Hydraulic pit props. GLOWNY INSTYTUT GORNICTWA. 22 March, 1968 [23 March, 1967], No. l3925/68. Heading E1P. In a hydraulic pit prop of piston-andcylinder construction 11, 37 having a built-in pump 1, 4 adapted.. to. feed-fluid from a reservoir 19 to a pressure chamber 36c via suction passages 17, 18, a one-way valve 20 and a delivery valve 22 the pump cylinder 4 is slidably mounted on a valve casing 7 and urged thereagainst by a spring 9 whereby when the pump piston 1, 2 is lifted in conjunction with its cylinder 4 the latter uncovers exhaust ports 8 in the casing 7 establishing communication between the chambers 36c and 19 for relief or release purposes. The pump is operated by a crank mechanism, see Figs. 1 and 2 (not shown) and the bore of the pump cylinder 4 is stepped to provide an annular surface acted on by pressure-fluid for pressure relief purposes. |
