| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic system for a leveling apparatus in an excavator and a forestry machine, which hydraulic system keeps an upper swiveling body horizontal even if a lower traveling body is tilt on a sloped surface. SOLUTION: The hydraulic system includes a pair of first and second actuators 6a and 6b which rock the upper swiveling body along the direction of a first tilt axis, another pair of third and fourth actuators 7a and 7b which rock the upper swiveling body along the direction of a second tilt axis, a first leveling control valve 23 which simultaneously controls extension and contraction drive by the first and second actuators 6a and 6b, a second leveling control valve 24 which simultaneously controls extension and contraction drive by the third and fourth actuators 7a and 7b, a reducing valve 25 which delivers a reducing pilot signal pressure, and a flow rate control valve 26 which delivers a pilot signal pressure for switching respective spools of the first leveling control valve 23 and the second leveling control valve 24 when a preset control signal is applied from a leveling controller 40. COPYRIGHT: (C)2009,JPO&INPIT |
