Abstract: A directional control valve includes a casing having a bore therein, a pair of inlet/outlet passages connected to a pair of inlet/outlet apertures, a U-shaped supply passage disposed between the inlet/outlet passages, a pair of reservoir passages between which the inlet/outlet passages are disposed and a plunger which has a plurality of land portions and is reciprocably movable in the bore into which the inlet/outlet passages and the U-shaped passage and the reservoir passages open, such that a fluid passed through the inlet/outlet apertures and the inlet/outlet passages and the U-shaped supply passage and the reservoir passages is controlled in response to a reciprocating motion of the plunger. A sub-reservoir is provided, through which one of the inlet/outlet passages is communicated with one of the reservoir passages.

Abstract: A multiple control valve for operating a civil construction machine or the like comprises a valve body, at least two parallel direction change-over plungers assembled in the valve body, by-pass passages and fluid supply passages formed in the valve body and operatively communicated with the plungers for feeding fluid from an external source to the plungers. One of plungers disposed most downstream side of the multiple control valve is provided with inner passages arranged on both sides thereof, a passage crossing the plunger, an axial passage having one end closed and the other end opened towards one of the inner passages, and a lateral port communicated with the inner passage. The crossing passage is communicated with the axial passage at a portion near the closed end thereof.

Abstract: A control valve operating as a combined relief and make-up valve for use in hydraulic apparatus comprises a valve housing provided with a blind hole, a valve seat tightly engaged with the inlet of the blind hole, a cylindrical hollow make-up poppet slidably inserted into the blind hole, a cylindrical relief poppet slidably inserted within the make-up poppet, a screw member adjustably engaged with the inner surface of the end of the make-up poppet, a coil spring disposed between the screw member and the relief poppet, and a balance piston having one end tightly inserted into the inner cylindrical hole of the relief poppet. The valve housing is provided with a first opening connected to an external hydraulic supply device and a second opening connected to a hydraulic source. The first and second openings are communicated with each other in response to differential pressure of an operating fluid so as to operate the control valve as a relief valve or a make-up valve.