Abstract: A pilot operated control valve includes a spool type pilot valve member which is coupled to the main valve member by a pair of springs so that both pilot pressure forces and spring forces act on the main valve member. The main valve member and the housing in which it moves enclose a damping chamber. A damping orifice extends through the main valve member and connects the damping chamber with a pilot pressure chamber to reduce vibration of the main valve member.

Abstract: An orifice controlled poppet valve includes a pilot poppet pressure balancing arrangement which prevents fluid leakage between the valve inlet and outlet. The pressure balancing arrangement includes a pin slidable in a passage in the main valve member, which passage extends between the inlet and a pilot outlet passage. One end of the pin engages a stem which projects from from the pilot poppet. The other end of the pin engages a flexible diaphragm which forms a seal between the valve inlet and the passage which receives the pin. An inlet pilot passage includes an annular clearance upstream of an orifice. The radial dimension of the annular clearance is smaller than the diameter of the orifice.

Abstract: A four-function valve for operating a 2-way hydraulic cylinder has a pair of solenoid-operated pilots. The valve also includes a pair of valve members and a pair of poppet members, all slidable within bores in a pair of hollow sleeves. The solenoid-operated pilot valves control pilot pressure communication to the valve members to control movement of the valve and poppet members. Each poppet member has a pair of seats, one engageable with a shoulder on the sleeve to control fluid flow between a pump and the cylinder, the other engageable with an end of the corresponding valve member to control fluid flow between a sump and the cylinder.

Abstract: A 4-way, 3-position, on-off type electrohydraulic valve includes a pair of solenoid-operated inlet valves for controlling communication between a pump and a valve bore. A pair of adjustable check valves are positioned in opposite ends of the valve bore. A double-acting pilot return valve assembly is operably mounted in a central portion of the valve bore and is movable to engage and open one of the check valves to return fluid flow when pump pressure flows through the other check valve to a fluid motor.

Abstract: A control system for controlling a double-acting cylinder includes four pilot-operated, proportional-type poppet valves for controlling fluid flow between the cylinder, a pump and a reservoir. Four solenoid-controlled pilot valves operate the poppet valves in response to error signals generated by a control circuit. The control circuit receives a cylinder position feedback signal and an operator-generated command signal. The control circuit provides for float, shutdown, variable deadband and pressure adjustment operation.

Abstract: A solenoid includes a coil, a pole assembly, an armature movable in the pole assembly and an air gap separating the armature from part of the pole assembly. A single mumetal washer may be fixed to the armature adjacent the air gap or a pair of mumetal washers may be fixed to the armature and to one of the pole parts on opposite sides of the air gap.

Abstract: A control system for controlling a double-acting cylinder includes four pilot-operated, proportional-type poppet valves for controlling fluid flow between the cylinder, a pump and a reservoir. Four solenoid-controlled pilot valves operate the poppet valves in response to error signals generated by a control circuit. The control circuit receives a cylinder position feedback signal and an operator-generated command signal. The control circuit provides for float, shutdown, variable deadband and pressure adjustment operation.