Hydraulic distributor valve for earth moving machine cylinder - has non return flow valves allowing cylinder venting when spool valves moved by control spool operation

摘要

The large capacity hydraulic valve comprises a body (1) in which is fitted a sliding spool (2). Dual springs (3, 4) control spool movement and are in one of two inlet chambers (5, 6). When either chamber (5, 6) is pressurised spool movement causes flow from the other end of the spool, past a spring loaded non-return valve (19, 18) and to one side of a double action hydraulic cylinder (22). The pressure in the chamber (5, 6) operates an adjacent spool valve (37) which allows release of pressure from behind the adjacent non-return valve (19, 18) so that return flow can occur from the other side of the hydraulic cylinder (22).