Abstract: A steering system that with a directional control valve 200 switchingly operating based on a pilot flow rate supplied from a steering motor unit 300 when a steering handle 330 is manipulated, that steers a vehicle 100 according to manipulation of the steering handle 330 by controlling a supply of pressure oil to cylinder actuators C1 and C2 through the directional control valve 200, includes an electromagnetic valve unit 600a, 600b that supplies a correction pilot pressure to the directional control valve 200 so as to correct a pilot pressure generated by the pilot flow rate from the steering motor unit 300 when a command signal is given.

Abstract: A pressure compensation valve unit comprises a check valve which is pushed in an opening direction thereof by an inlet side pressure and in a closing direction thereof by an outlet side pressure and a pressure reducing valve actuating to establish communication between the inlet side and the outlet side and block the communication therebetween, pushed in the blocking up direction by a pressure in a pressure receiving chamber to push the check valve in the closing direction thereof, pushed in the communication direction with a highest pressure in a plurality of pressures by a pressure selective receiving means, and communicating the outlet side with the pressure chamber, and a pressure oil supply system is provided with the pressure compensation valve unit of the structure described above.

Abstract: A pilot pressure operated directional control valve is provided in which a housing is formed therein with a spool having a plurality of ports. The spool bore has a spool fittingly inserted therein so as to be slidably displaceable therein and the spool is slidably displaced both by a spring and under a pilot pressure led into a pressure receiving chamber. Also a spring box is attached to an end surface of the housing in a longitudinal direction of the spool. The spring box is provided with a hollow portion which contains the spring while forming a pressure receiving chamber, as well as a pilot pressure fluid inlet that communicates with the hollow portion and is open in the longitudinal direction of the spool.

Abstract: An unloading system including an unload valve draining a part of supplied pressurized fluid to a tank and a switching valve for draining a pressurized fluid for biasing the unload valve in a direction for reducing a flow rate of the fluid supplied to the tank. The unload valve and the switching valve are arranged in series in axial direction in a valve main body.

Abstract: A direction control valve is constructed in such a manner that a spool bore having an inlet port, an actuator port and a tank port is formed in a valve block, a spool slidable between positions for establishing and blocking communication of the input port, the actuator port and the tank port, is disposed within the spool bore, the input port and the tank port open to a first mateable surface and a second mateable surface of the valve block, and a plurality of the valve blocks are stacked and connected with mating the first mateable surface and the second mateable surface for establishing communication between the input ports and between the tank ports of the valve blocks.

Abstract: An operating valve assembly with an electromagnetic proportioning pressure reduction valve comprises an operating valve constructed by slidably disposing a spool in a spool bore opening to an end face of a valve body, mounting a spring case including a case body having a blind bore and a housing having a spool bore for a pressure reduction valve on the end face in a manner such that the spool bore and the blind bore are matched to each other, and defining a pressure receiving chamber between the interior wall of the blind bore of the spring case and the end portion of the spool, and the electromagnetic proportioning pressure reduction valve constructed by disposing a spool for the pressure reduction valve in the spool bore for the pressure reduction valve, and mounting a solenoid for driving the spool for the pressure reduction valve on the housing, and an output port of the electromagnetic proportioning pressure reduction valve is communicated with the pressure receiving chamber.

Abstract: A multiple valve includes first and second valve units respectively having first and second valve bodies. The first and second valve bodies have respective spool bores therein; and a respective spool is inserted in the spool bore of each of the first and second valve bodies. The first and second valve bodies of the first and second valve units also have inlet ports, tank ports, and first and second blocks having mounting holes, the blocks and a respective valve body being fixedly coupled together by means of stud bolts. The first block has a first threaded hole on one side surface thereof for receiving the stud bolt, and a second threaded hole on another side surface thereof for receiving a cover bolt. A pump passage, a main passage and a tank passage extend between the one side surface and the another side surface of the first block, and a stud bolt extends through the second block and is engaged with the first threaded hole.

Abstract: A pressurized fluid supply system, in which a plurality of pressure compensation valves are connected to a pump discharge line of a hydraulic pump in parallel, and direction control valves are provided at the outlet side of each pressure compensation valve to supply a discharged pressurized fluid from the hydraulic pump to a plurality of actuators. The pressure compensation valves include a check valve portion establishing and blocking communication between the pump discharge line and the inlet port of the direction control valve, and a pressure reduction valve portion for supplying a reduced pressure from the pump discharge line. The check valve portion shifts in a valve opening direction in response to an inlet pressure and shifts in a valve closing direction in response to an outlet pressure. The pressure reduction valve portion has a first and a second pressure chamber.