Hitachi Construction Machinery Co., Ltd.

Hitoshi Kagiwada

Tomohiko Yasuoka

Genroku Sugiyama

Toichi Hirata

Hiroshi Watanabe

Hideaki Tanaka

Eiki Izumi

Hiroshi Onoue

Takeshi Kobayashi

Takashi Niidome

Hitoshi Sato

Kenichi Kimura

A volume control valve for controlling the volume of a variable displacement type hydraulic rotary machine includes a valve housing provided with a bore in which a spool slides axially to selectively establish and block communication of a pressure oil feed/discharge port with a high pressure port and a tank port. A first pressure receiving portion is formed in the spool to receive a load pressure as a pilot pressure introduced from a pilot port for displacing the spool axially within the bore. A bottomed axial bore is formed in the spool which has a slidable piston therein defining an oil chamber between the piston end and the bottom of the bore to receive a hydraulic reaction force induced within the oil chamber. A second pressure receiving portion is formed by the bottom of the bore to receive an internal pressure of the oil chamber, thereby changing a total pressure receiving area of the spool in conjunction with the first pressure receiving portion. An oil passage is formed in the spool at a position corresponding to the oil chamber.

Volume control valve of variable displacement hydraulic rotating machine

Swash plate type hydraulic rotating machine and method of manufacturing

Hydraulic-motor drive circuit system with anti-cavitation control

Hydraulic drive traveling system

Growing community of inventors

Tsuchiura, Japan

Hitoshi Kagiwada