Title:
HYDRAULIC CIRCUIT FOR WORKING DEVICE
Document Type and Number:
Japanese Patent JP3516514
Kind Code:
B2
Abstract:
PURPOSE: To provide a compact and inexpensive hydraulic circuit with good efficiency in which a lock valve is installed to each port of the bottom or head side of a boom lock cylinder, and the valve is connected to the pilot operating circuit of a boom main valve through a mode switching valve, and operated.
CONSTITUTION: This circuit has a boom operating valve 8 connected to a boom operating lever 7 for pilot-operating a boom main valve 2; the boom main valve 2 switched by receiving the pressure from the boom operating valve 8; a two-port two-position spring offset pilot type lock valve 4 for connecting an oil passage which is inserted between a boom lock cylinder 5 and a tank 11; and a posture control valve 10 inserted to a pilot circuit between the lock valve 3 and the boom operating valve 8 to switch a working device 30 to either one of housing posture and working posture. At posture switching, the boom operating valve 8 is operated, and the lock valve 4 also is switched to suck the oil in the tank 11 into the boom lock cylinder 5 so that it can be expanded and contracted.
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Inventors:
Sasaki, Hidetoshi
Application Number:
JP8862995A
Publication Date:
April 05, 2004
Filing Date:
March 23, 1995
Export Citation:
Assignee:
KOMATSU LTD
International Classes:
E02F9/22; E02F3/36; F15B11/17; (IPC1-7): E02F3/36; E02F9/22; F15B11/17