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:
May. 17, 2016
Filed:
May. 17, 2012
Tsuyoshi Nakamura, Tsuchiura, JP;
Kazunori Nakamura, Tsuchiura, JP;
Yasuo Okano, Tsuchiura, JP;
Kouji Ishikawa, Tsuchiura, JP;
Kensuke Sato, Tsuchiura, JP;
Hiroyuki Azuma, Tsuchiura, JP;
Mitsuhiko Kanehama, Tsuchiura, JP;
Yusuke Kajita, Tsuchiura, JP;
Tsuyoshi Nakamura, Tsuchiura, JP;
Kazunori Nakamura, Tsuchiura, JP;
Yasuo Okano, Tsuchiura, JP;
Kouji Ishikawa, Tsuchiura, JP;
Kensuke Sato, Tsuchiura, JP;
Hiroyuki Azuma, Tsuchiura, JP;
Mitsuhiko Kanehama, Tsuchiura, JP;
Yusuke Kajita, Tsuchiura, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A hydraulic drive device for a hydraulic excavator, includes: a first hydraulic pump; a first boom directional control valve and a second arm directional control valve which are connected in parallel to the first pump; a second hydraulic pump; and a second boom directional control valve and a first arm directional control valve which are connected in parallel to the second pump; wherein: the hydraulic drive device also includes: a third hydraulic pump; a third boom directional control valve connected to the third pump and controlling the flow of pressure oil supplied to a boom cylinder; and a third arm directional control valve connected in tandem with the third boom directional control valve and controlling the flow of pressure oil supplied to an arm cylinder.