Title:
HYDRAULIC CIRCUIT OF WORKING MACHINE
Document Type and Number:
WIPO Patent Application WO/2003/027505
Kind Code:
A1
Abstract:
A hydraulic circuit of a working machine capable of preventing all actuators from being functionally stopped when a pilot hydraulic pressure supply source fails to assure the least safety, wherein an unloading oil passage selector valve (35) is installed between an unloading hydraulic passage leading to an oil tank and oil passages (36) and (40) for supplying oil to the control valves of the hydraulic actuators, and a first hydraulic pump (31), and a directional control valve (50) is installed in the discharge oil passage of a second hydraulic pump (32) in the working machine formed so that the hydraulic pressure supply controls of the plurality of hydraulic actuators are performed by the corresponding control valves and the selecting operations of the control valves are performed by using pilot−operated means and the other operating means such as manual operating means, the directional control valve (50) comprises two ports having oil feed directions different from each other and the ports are made switchable between a direction for supplying pressure oil from the second hydraulic pump (32) and a direction for supplying pressure oil to the oil tank by a safety lever (50a).
Inventors:
KONDO MASAMI (JP)
Application Number:
PCT/JP2002/009809
Publication Date:
April 03, 2003
Filing Date:
September 24, 2002
Export Citation:
Assignee:
YANMAR CO LTD (JP)
KONDO MASAMI (JP)
KONDO MASAMI (JP)
International Classes:
E02F9/22; E02F9/24; F15B11/00; F15B11/17; F15B20/00; (IPC1-7): F14B11/08; E02F9/24; F15B11/00; F15B20/00
Foreign References:
| JPH09329107A | 1997-12-22 | |||
| EP1022395A1 | 2000-07-26 | |||
| JP2000205141A | 2000-07-25 | |||
| JP2001311407A | 2001-11-09 | |||
| JPH11280701A | 1999-10-15 |
Attorney, Agent or Firm:
Yano, Juichiro (Twin 21 MID Tower 34th Floor, 1-61, Shiromi 2-chome,Chuo-k, Osaka-shi Osaka, JP)
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