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. 04, 2003
Filed:
Sep. 18, 2001
Kenichiro Nakatani, Shiga, JP;
Takashi Kanai, Kashiwa, JP;
Yasutaka Tsuruga, Moriyama, 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
An actuator lock switching valve is provided which communicates a drain line and a pilot line with each other when the valve is in a position C, and which communicates pilot lines with each other when it is shifted to a position D. The pilot line is connected to a delivery line of a hydraulic pump , and the pilot line is connected to pressure receiving sections provided at ends of the pressure compensating valves on the side acting in the closing direction. The actuator lock switching valve has a pressure receiving section connected to the output side of a pilot lock switching valve , and is switched over in interlock with shifting of the switching valve . In a hydraulic drive system including pressure compensating valves controlled by an LS system, an actuator can be locked with a simple construction and can be prevented from malfunctioning in an inoperative condition while an engine is being driven, even when the system includes a mechanically shifted directional control valve, or even when a mechanically shifted directional control valve is retrofitted to the system.