GB860052A - Improvements in and relating to hydraulic mechanisms - Google Patents

Abstract

860,052. Hydraulic control systems. BOSCH G.m.b.H., R. Jan. 20, 1959 [Jan. 21, 1958], No. 2029/59. Class 69 (2). An hydraulic control system for a piston-andcylinder device 14, 17, Fig. 1, such as may be mounted on a tractor or the like, comprises a mechanism 5 for controlling the supply of liquid from a pump 3 to the cylinder, and an operating mechanism 9 having passages 29, 30 therethrough insertable between the control mechanism and the cylinder 14 and at least one additional passage 31 for connection to an additional piston-and-cylinder device 15, 18, the operating mechanism having a selectively adjustable member for operating closure members 26, 27 in the passages whereby the devices 14, 17 and 15, 18 are under joint or separate control. The control mechanism 5 is adjustable to three positions in which (1) a pipe 4 from the pump is connected by a pipe 7 to the operating mechanism, (2) the pipe 4 is connected to a pipe 24 and tank 1, or (3) both pipes 4 and 7 are connected to the pipe 24. The operating mechanism can be adjusted so that one or other of the closure members 26, 27 is open or both members are either open or closed. The combined controls permit one or other or both of the pistons to be moved to the end of its stroke, retained there, and returned to the initial position. With both closure members open, the cylinders are inter-connected to enable the pistons to take up a position of equilibrium. A throttle valve may be included in one or other of pipes 10, 11 to vary the rate of movement of one piston relative to the other. In other embodiments, the remote end of one or both of the cylinders may be connected by a pipe to the operating and control mechanism so that one or both of the cylinders may be double-acting. The operating mechanism consists of a housing 41, Fig. 3, having bores 45, 46 in which are the closure members 71, 72 spring-urged towards a shaft 51 having cam surfaces 67, 68 arranged so that, at various angular positions of the shaft determined by engagement of a spring-pressed ball 60 with recesses 59, one or other, both or neither of the members are lifted from their seats 48, 49 to control the connection between a common passage 85, 86 from the pump and passages 43, 88, connected to the cylinders. A slot 66 in the shaft 51 permits oil which leaks past the stems of the closure members to return to the tank. A spring- controlled valve in a bore 90 connected to the passages 43, 88 leading to the cylinders is provided to relieve excess pressure that may occur in the cylinders. A separate closure member with an additional position of the operating member may be provided for the independent control of each additional piston-and-cylinder device.