| 摘要 |
PROBLEM TO BE SOLVED: To stop an abnormal operation and to safely lift down a worker on the ground when an abnormality is generated in a leveling device. SOLUTION: Hydraulic fluid is supplied to a control valve 50 from a hydraulic pump P via an oil path 61. A controller 40 electromagnetically drives a rise and fall control valve 51 based on a rise and fall operation of a boom operation lever 27 and a rise and fall cylinder 16 is made to perform a rise and fall operation. At the same time, a leveling control valve 55 is electromagnetically driven according to an inclined angle of an inclination detecting device 45 disposed on a work bench, a leveling cylinder 23 is operated and a leveling control is performed for the work bench. In oil paths 63, 64 for linking the leveling control valve 55 and the leveling cylinder 23, an interruption valve 57 is disposed and the controller 40 interrupts the oil paths 63, 64 when an abnormality is generated in leveling control.
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