The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 01, 2003
Filed:
Sep. 12, 2001
Yasutaka Tsuruga, Moriyama, JP;
Takashi Kanai, Kashiwa, JP;
Junya Kawamoto, Moriyama, JP;
Satoshi Hamamoto, Toyama-ken, JP;
Yasuharu Okazaki, Takaoka, JP;
Yukiaki Nagao, Toyama, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
In a hydraulic drive system in which a target compensated differential pressure for each of pressure compensating valves is set in accordance with a differential pressure between a pump delivery pressure and a maximum load pressure, and a target LS differential pressure is set as a variable value depending on a revolution speed of an engine a fixed throttle and a signal pressure variable relief valve are disposed in a maximum load pressure line A relief setting pressure P of the signal pressure variable relief valve is set so as to satisfy P =P −P +a (where a is a value smaller than P ) with respect to a target LS differential pressure P and a setting pressure P of the main relief valve