HYDRAULIC CONTROL CIRCUIT OF WORKING MACHINE

Title:

HYDRAULIC CONTROL CIRCUIT OF WORKING MACHINE

Document Type and Number:

WIPO Patent Application WO/2002/055889

Kind Code:

A1

Abstract:

A hydraulic control circuit, comprising a boom cylinder for vertically moving a boom, a control valve for controlling the supply and discharge of pressure oil to and from the boom cylinder, and a regenerative circuit for supplying a part of the discharged oil from the head side oil chamber of the boom cylinder to the rod side oil chamber, wherein a discharge valve path (15d) for performing the discharge of oil from the head side oil chamber (8a) of the boom cylinder (8) to an oil tank (13) when the boom is lowered is provided in a second boom section control valve (15) and the discharge valve path is opened and closed based on the selection of a boom lowering speed selector switch (22), whereby a boom lowering speed can be varied according to the type of a work and the skill of an operator.

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JP6205339	Hydraulic drive
JP5676130	Control method of hydraulic pump and construction machinery using the same method

Inventors:

YOSHINO TETSUYA (JP)
SHIMADA YOSHIYUKI (JP)

Application Number:

PCT/JP2001/011006

Publication Date:

July 18, 2002

Filing Date:

December 14, 2001

Export Citation:

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Assignee:

CATERPILLAR MITSUBISHI LTD (JP)
YOSHINO TETSUYA (JP)
SHIMADA YOSHIYUKI (JP)

International Classes:

E02F9/22; F15B11/02; F15B11/024; F15B21/14; (IPC1-7): F15B11/04

Foreign References:

JPH06113603A	1994-04-26
JP2000344493A	2000-12-12
JPS49100747A	1974-09-24
JPH11247805A	1999-09-14
JPS52129889A	1977-10-31
US3641876A	1972-02-15
JPH04362285A	1992-12-15

Attorney, Agent or Firm:

Hirose, Tetsuo (Tokyo, JP)

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