| 摘要 |
PROBLEM TO BE SOLVED: To shut off hydraulic pressure supply to a lift arm during the mounting of a backhoe and prevent interference with the lift arm by changing over and supplying the hydraulic pressure of a main hydraulic pump to the lift arm and the backhoe by a changeover spool. SOLUTION: In a backhoe mounted detachably on a tractor, hydraulic pressure is fed through an exclusive circuit 37A and a control valve 29 by an exclusive hydraulic pump to a swing cylinder 23, and fed through each control valve 30-34 via a directional control valve 39 and a control valve 40 by a main hydraulic pump 36 to other cylinders 24-27. A changeover spool is provided on the control valve 40 to change over and feed hydraulic pressure to a hydraulic device 10. Thereby in the case where a backhoe is mounted, hydraulic pressure feed is shut off to the hydraulic device 10, the backhoe is arranged close to a tractor, the front and rear weight balance of the tractor is improved, and entire length can be shortened.
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