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:
Mar. 05, 2013
Filed:
Feb. 26, 2010
Kazuyoshi Hanakawa, Tsuchiura, JP;
Makoto Mitsuhashi, Ibaraki-ken, JP;
Tsuyoshi Nakamura, Tsuchiura, JP;
Kazuyoshi Hanakawa, Tsuchiura, JP;
Makoto Mitsuhashi, Ibaraki-ken, JP;
Tsuyoshi Nakamura, Tsuchiura, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A hydraulic circuit system for a hydraulic excavator, which has a hydraulic circuit for an attachment, includes: a directional control valvethat supplies a hydraulic fluid to an attachment connected to the hydraulic circuit for an attachment; a first over-load relief valve unitthat is provided in one of lines of the hydraulic circuit for an attachment; a second over-load relief valve unitthat is provided in the other of the lines of the hydraulic circuit for an attachment; a first proportional solenoid valvethat controls set relief pressure of the first over-load relief valve unit; and a second proportional solenoid valvethat controls set relief pressure of the second over-load relief valve unit. The attachment having various characteristics and capacity, such as a hydraulic breaker or a crusher, can be applied to the hydraulic circuit for an attachment in a simple configuration.