GB546324A - Improvements in power transmission systems - Google Patents

Abstract

546,324. Hydraulic machines. VICKERS, Inc., and HARRINGTON, F. T. July 17, 1941, No. 9038. [Class 69 (ii)] In a hydraulic power system for operating shaping, planing or broaching machines so as to provide a quick return for the tool, of the kind in which the tool is operated by a differentialarea cylinder-and-piston motor 10, 12 supplied with oil from a pump 26, a multi-position directional control valve 24 is provided to control the supply of oil, and by means of a lever 80 the valve can be set to an inoperative position, or to positions in which (1) a restricted supply of oil is directed to the pipe 16 in order to move the piston to left for the operative stroke, (2) an unrestricted supply is directed to the pipe 18 and left hand end of the cylinder in order to produce a quick return, which is enhanced by the connection of the exhaust from the cylinder by the pipe 16 being connected through the valve to the pipe 18. The valve 24 is formed with five lands 66, 68, 70, 72 and 74 and with a bore 64 which connects the spaces between the lands 68, 70 and 72, 74. In the inoperative position of the valve shown the oil discharged by the pump 26 passes via pipe 34 through the passage 64 and returns via pipes 58, 50 to tank 32. On movement of the lever 80 to the right to a position in which the left of these grooves in the valve spindle is held by a spring catch 82, the pump outlet passes via a pipe 38, a controlled throttle device 46, pipe 42 and space between the lands 70, 72 to pipe 16 and the right hand end of the cylinder. The return is via pipes 18, 61 and a back-pressure valve 62 to the tank 32. Associated with the throttle 46 is a balanced piston valve 52 which regulates the flow through a byepass port 48 and so maintains a predetermined pressure drop across the throttle 46. A pilot relief valve 54 limits the pressure in the conduits 38, 42. When the lever 80 is moved to the left, the oil flows from the pipe 34 through the valve 24 to the pipe 18 and the left hand end of the cylinder, and the outlet pipe also connects through the valve to the pipe 18 and so helps to speed up the return. Specification 516,397 is referred to