GB1281367A - Hydraulic control valve - Google Patents

Abstract

1281367 Valves COMMERCIAL SHEARING & STAMPING CO 23 Oct 1969 51994/69 Heading F2V An hydraulic control valve which is biased to a neutral position by means of a spring and flange arrangement 40, 41, 42 and which is used to control a motor 80, comprises a hollow spool valve member 16 having formed therein three sets of ports 47, 58 and 60, two check valves 51 and 64 disposed one at each end of the valve member, two inlet chambers 18 and 19 fed from a common source, an outlet chamber 20, a passage 24 extends transversely to the valve bore 14 and which communicates with the bore via a passage 23, the passage 24 being connnected to the source feeding the inlet chambers, two exhaust chambers 34, 35 and two working chambers 31 and 32. When in the position shown, fluid from the inlet chambers 18 and 19 is caused to flow to the outlet chamber 20 and accordingly motor 80 remains stationary. When the spool is moved to the left as seen in the drawing, (Fig. 4, not shown), motor line 84 is fed from the transverse passage 24 by way of passage 23, ports 58, the spool interior, ports 60 and working chamber 32, return flow from the motor being by way of motor line 82, working chamber 31, spool recess 76 and exhaust chamber 34. During the above indicated state of the valve, check valve 64 is maintained unseated by the fluid pressure acting thereon. When the spool is moved to the right of the neutral position (Fig. 5, not shown) supply to the motor takes place from inlet 18, over spool recess 76 and into chamber 31 and motor line 82, whilst exhaust of line 84 takes place through line 84, chamber 32, ports 58 and 60, and chamber 35. In such circumstances, the inlet pressure augments the spring force acting on check valve 51 and so maintains it seated whilst the pressure of the return unseats check valve 64. In the event of cavitation taking place at the piston end of the motor 80, the resulting pressure differential across check valve 51 causes it to open and to allow some of the return flow to be fed into line 82, such flow taking place from chamber 32, through ports 58, through the spool interior, past check valve 51, through ports 47, and into chamber 31.