GB912364A - Improved hydraulic means for the fluid pressurisation of hydraulically operable components - Google Patents

Abstract

912,364. Hydraulic apparatus. MUSCHAMP & CO. Ltd., N. J. March 20, 1959 [June 5, 1958], No. 17956/58. Class 69 (2). An hydraulic intensifier 13 for pressurization of hydraulically-operable components 1-6, such as roof supports for underground mines, comprises a differential piston 20 automatically displaceable consequent upon inadequate pressure in the components, and fluid control means 27 which provide the piston with power and return strokes until adequate pressure is obtained. The control member 27 consists of an annular member which is disposed on a reduced portion 20a of the large diameter portion 21 of the piston and has grooves 27b, 27c co-operating with an inlet port 23 connected by means of a valve 8 to a supply line 9, an exhaust port 126 and spring-pressed balls 28. The member 27 is axially movable in the intensifier cylinder during the movement of the piston by abutment of portions 20b, 21a thereon and springs 29, 30. In operation, a piston-and-cylinder device 7 supplied with fluid pressure from the line 9 is actuated to advance the supports step-by-step until they engage the roof. The fluid from the line 9 then passes through the inlet port 23 and apertures 27d in the groove 27c to move the piston to the right to pressurize fluid in a cylinder 16 supplied from the line 9 through a one-way valve 25, the pressurized fluid then passing through a one-way valve 19 and pipe 18 to the supports. As the piston moves to the right, the portion 20b and spring 29 move the member 27 to the right so that the balls 28 engage the groove 27b. The inlet port 23 is thus closed, the exhaust port 126 opened and the supply from the line 9 to the cylinder 16 moves the piston to the left until the portion 21a and spring 30 return the member 27 to its first position for the next power stroke of the piston. The operation continues until the ratio of pressures in the lines 9, 18 is the same as the ratio of the areas of the portions 21, 22 of the piston. The intensifier will automatically operate to maintain the pressure in the supports in the event of any drop in pressure. Relief valves 11, 12 are provided to reduce the pressure in the supports if the pressure therein rises above a predetermined level. A manually-operable pressure valve 26 enables different values of high pressure to be obtained from the intensifier.