(19)
(11) EP 1 726 723 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
31.01.2007 Bulletin 2007/05

(43) Date of publication A2:
29.11.2006 Bulletin 2006/48

(21) Application number: 06113452.4

(22) Date of filing: 03.05.2006
(51) International Patent Classification (IPC): 
E02F 9/22(2006.01)
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR
Designated Extension States:
AL BA HR MK YU

(30) Priority: 26.05.2005 JP 2005154632

(71) Applicant: KOBELCO CONSTRUCTION MACHINERY CO., LTD.
Hiroshima-shi, Hiroshima 731-0138 (JP)

(72) Inventors:
  • Toji, Yutaka
    Asaminami-ku Hiroshima-shi Hiroshima (JP)
  • Yamazaki, Yoichiro
    Asaminami-ku Hiroshima-shi Hiroshima (JP)
  • Oka, Hidekazu
    Asaminami-ku Hiroshima-shi Hiroshima (JP)
  • Ueda, Koji
    Asaminami-ku Hiroshima-shi Hiroshima (JP)

(74) Representative: Brookes Batchellor LLP 
102-108 Clerkenwell Road
London EC1M 5SA
London EC1M 5SA (GB)

   


(54) Working machine


(57) A working machine includes a hydraulic control apparatus. In a straight travel valve (32) of the hydraulic control apparatus, a communication path (35) and a control valve (36) that opens and closes the communication path (35) are provided. During a combined operation of travelling operation and working operation, a working pressure (41) and a travelling pressure (42) are taken in as pilot pressures on either side of the control valve (36). During a small travelling operation in which the travelling operation amount is small, the communication path (35) is unconditionally closed. During a large travelling operation in which the travelling operation amount is large, if the working pressure (41) is higher than the travelling pressure (42), the communication path (35) is open, and if the working pressure (41) is lower than the travelling pressure (42), the communication path (35) is closed.







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