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Patent Searching and Data


Title:
HYDRAULIC DRIVE DEVICE FOR HYDRAULIC WORKING MACHINE
Document Type and Number:
WIPO Patent Application WO/2011/027791
Kind Code:
A1
Abstract:
Provided is a hydraulic drive device for a hydraulic working machine by which a jack-up operation can be realized without providing a center by-pass change-over valve and a flow control valve enabling supplying of a pressurized oil to a direction control valve for a working element. The hydraulic drive device for a hydraulic working machine is provided with: a first hydraulic pump (21) and a second hydraulic pump (22); a first boom direction control valve (28) and a second boom direction control valve (29) for controlling a boom cylinder (9); and a third boom direction control valve (30) for controlling the boom cylinder (9) and a third hydraulic pump (23) for supplying a pressurized oil to the third boom direction control valve (30). The jack-up change-over valve (31) has a second change-over position (31b) in which when the pressure in a bottom chamber (9a) of the boom cylinder (9) is below a predetermined pressure, the pressurized oil discharged from the second hydraulic pump (22) and the third hydraulic pump (23) can be supplied to a rod chamber (9b) of the boom cylinder (9) in accordance with the change-over of the second boom direction control valve (29) and the third boom direction control valve (30) by the operation of an operation device (32).

Inventors:
OKANO YASUO (JP)
NAKAMURA TSUYOSHI (JP)
ISHIKAWA KOUJI (JP)
SATO KENSUKE (JP)
HAGIWARA NAOKI (JP)
Application Number:
JP2010/064951
Publication Date:
March 10, 2011
Filing Date:
September 01, 2010
Export Citation:
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Assignee:
HITACHI CONSTRUCTION MACHINERY (?1128563, JP)
OKANO YASUO (?1128563, JP)
NAKAMURA TSUYOSHI (JP)
ISHIKAWA KOUJI (JP)
SATO KENSUKE (JP)
HAGIWARA NAOKI (JP)
International Classes:
F15B11/02; E02F9/22; F15B11/024; F15B11/08; F15B11/17
Foreign References:
JPH062344A1994-01-11
JPS61116102A1986-06-03
JPH02136432A1990-05-25
JP2002115274A2002-04-19
JP2002181004A2002-06-26
JP2008185099A2008-08-14
Other References:
See also references of EP 2474746A4
None
Attorney, Agent or Firm:
The Patent Body Corporate TAKEWA INTERNATIONAL PATENT OFFICE (?1050003, JP)
Patent business corporation Takekazu international patent firm (?1050003, JP)
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