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:
Feb. 20, 2007
Filed:
Mar. 14, 2005
Hidekazu Oka, Hiroshima, JP;
Hidekazu Oka, Hiroshima, JP;
Kobelco Construction Machinery Co., Ltd., Hiroshima, JP;
Abstract
A hydraulic control system for a hydraulic excavator of the present invention comprises a boom control valve in a first oil path for providing pressure oil from a first hydraulic pump with a boom cylinder according to operation of a boom operating means, an arm control valve in a second oil path for providing pressure oil from a second hydraulic pump with an arm cylinder according to operation of an arm operating means, a confluence switching valve having a confluence position for joining the paths and a confluence stop position for stopping the confluence, a flow control valve for returning pressure oil in the first oil path to a tank, and a control means for controlling the valves, so as to switch the confluence switching valve to the confluence position and close the flow control valve when the arm operating means is operated independently and so as to switch the confluence switching valve to the confluence stop position and open the flow control valve when both of the operating means are operated simultaneously, thereby, the arm pulling operation is performed independently, an arm cylinder speed increases and a leveling efficiency is improved.