Hitachi Construction Machinery Co., Ltd.

Kayaba Industry Company, Ltd.

Masao Kashiwagi

Genroku Sugiyama

Toichi Hirata

Tsukasa Toyooka

Masayuki Nakamura

Ikuo Inagaki

Norio Onuma

A tournament oil path constituting apparatus in which while a laminated block is constituted by laminating a number of oil path plates, a number of shuttle valve holes and connection grooves made continuous to the shuttle valve holes are formed at overlap faces of the oil path plates, shuttle valves are integrated to the shuttle valve holes, introductory oil paths communicating with the shuttle valve holes are formed at both of the oil path plates formed with the shuttle valve holes and the oil path plates having match faces on sides of the shuttle valve holes and a high pressure oil is selected by the shuttle valves from pressure oils conducted both of the introductory oil paths and conducted to the connection grooves. The tournament oil path constituting apparatus also including a number of main paths penetrating the number of laminated oil path plates and branch grooves branched from the main paths.

Tournament oil path constituting apparatus

The present invention is directed to a hydraulic pressure control device which can overcome problems, such as a shock to an actuator or a pressure boost phenomenon involving a rapid increase in pump delivery pressure, conventionally encountered when a directional control valve is switched. The hydraulic pressure control device is constructed such that first and second connecting ports are connected to a tank when a directional control valve is in its neutral position, one of the first and second connecting ports is cut off from the tank and connected to an actuator and the other is cut off from the tank and closed when the directional control valve has been switched, in accordance with a position to which the directional control valve has been switched, and a maximum pilot pressure selectively taken from between a pressure compensating valve and a pair of check valves is introduced into a pilot line.

Hydraulic pressure control device

Growing community of inventors

Sagamihara, Japan

Masao Kashiwagi