| 摘要 |
PROBLEM TO BE SOLVED: To provide pile installation by inner excavator capable of synchronizing with expansion control of a forced cylinder to drive a risng and falling hydraulic motor and making simply earth-moving operaion. SOLUTION: An auger driving device 10 for driving an auger screw 3 is interlocked with a rack or a chain fixed to a leader to make it rise and fall, and a hollow pile 4 is erected while making excavation by means of the auger screw 3 inserted into the hollow pile 4. In that case, a hydraulic motor 11 driving a pinion or a sprocket engaging with the rack or the chain and a forced cylinder 6 of the hollow pile 4 are connected to the same hydraulic pump 21 through a vertical selector valve 22, a rising side of the hydraulic motor 11 is linked with an expansion side of the forced cylinder 6 and, at the same time, a falling side of the hydraulic motor 11 is linked with a contraction side of the forced cylinder 6. A harmonic selector valve 23 harmonically or separately switching the hydraulic motor 11 and forced cylinder 6 is provided between the vertical selector valve 22 and hydraulic motor 11/forced cylinder 6, and the revolution of the hydraulic motor 11 is harmonized with the action of the forced cylinder 6 when earth-moving operation is made.
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