GB916936A - Improvements in or relating to extensible mine support elements - Google Patents

Abstract

916,936. Hydraulic pit props. EGGEMANN, W., and VON CAMPENHAUSEN, E., [trading as SCHWARZ KOMM.-GES., HERMANN]. Sept. 14, 1959 [Sept. 13, 1958], No. 31169/59. Class 20 (2). A telescopic hydraulic pit prop comprises two pressure chambers 27, 28, Fig. 1, or 27, 54, Fig. 5. The auxiliary chamber 28, Fig. 1, is formed in a floating piston 32 and is charged by water under pressure through a pipe 21, valve 19 and pipe 21a which increases the loading of the prop already provided by oil under pressure in the main chamber 27 forced through hose 29 and pipes 25, 23 by air pressure in the reservoir piston 13 supplied through a pipe 20, valve 19, and a stub pipe 20a. The water in the chamber 28 is released by a valve in a pipe coupling 18 and the oil in the chamber 27 is returned to the reservoir by a valve in a casing 22 in which there is also an automatic relief valve. In a modification, Figs. 3, 4 (not shown), the piston 32 has a coaxial cylindrical part guided in a bore at the lower end of the pipe 25 which is connected by a bore in the piston 32 with the pressure chamber 27. In Fig. 5, the auxiliary chamber 54 is in a head 14 sliding on the top of the prop piston 13 and has a rubber lining 55 vulcanized to both parts and is supplied with water through a pipe 58. The reservoir in the piston 13 is in two parts 26, 39 connected by a passage 41 in a plate 40 carrying the valve mechanism. A relief and release valve 52 is provided for the main pressure chamber 27 and a release valve 45 for the pressure chamber 54. Excessive upward movement of the head 14 opens a valve 63 by a chain 62 to release water.