| 摘要 |
PROBLEM TO BE SOLVED: To certainly press-fit a pile to a point to provide specified large soil bearing power with no vibration and no noise by certainly generating large reaction force and using it. SOLUTION: It is furnished with an outside cylinder 1 furnished with a plural number of switching vanes 13 free to revolve and to intrude in soil while rotating, a working shaft 2 inserted into the outside cylinder 1 free to slide in the axial direction and in the peripheral direction, to intrude in soil while rotating in the normal rotating direction integrally with the outside cylinder 1 and to extract from soil integrally with the outside cylinder l while rotating in the resersing direction and a switching mechanism to store the switching vanes 13 on the side of the outside cylinder 1 at the time of intruding the working shaft 2 in soil normally, to develop the switching vanes 13 by retreating motion of the working shaft 2 in the longitudinal direction against the outside cylinder 1 in soil and to hold storing motion of the switching vanes 13 at the time of earth reversal extracting motion of the working shaft 2 in a state of storing the switching vanes 13. Thereby, pile driving work, etc., is carried out by developing the switching vanes 13 at the time when it is made to intrude to a specified point and increasing reaction force.
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