HIGH PRESSURE HYDRAULIC FLOW CONTROL VALVE

摘要

A high pressure hydraulic flow control valve (16) is formed with a spool (62) which is capable of operating as a conventional spool to control the flow of fluid from an input port (38) to an output port (40) or to a return port (50). The spool also provides overload protection which will permit fluid to pass from the input port (38) directly to the return port (50) when an overload pressure condition exists in the fluid supply line. In alternative structure, the overload pressure release system may be incorporated into the valve which is used to control the return of fluid from the output port (40) to the return passage (50). The high pressure hydraulic flow control valve is formed from a die-cast housing (34) and has hardened seats mounted in access passages so as to bear against a seating shoulder. Preferably, a retaining sleeve is mounted in the access passage to bear against the hardened seat to retain it against the seating shoulder.