| 摘要 |
PROBLEM TO BE SOLVED: To provide a lifter for an earth auger, in which the relative distance between the extremity of a screw and the top of a casing can be taken large discretionally. SOLUTION: In the earth auger, an outer spindle driving unit 5 driving a cylindrical outer spindle and a center spindle driving unit 4 driving a center spindle concentrically arranged inside the cylindrical outer spindle are hung on a leader 2 via a winch provided on a base machine 1, so that the driving units can be lifted up and down. The outer spindle driving unit 5 and the center spindle driving unit 4 are separately hung via the hydraulic drive winch, and a distance sensor 15 is arranged on the outer spindle driving unit 5 or the center spindle driving unit 4, the distance sensor measuring the relative distance between the outer spindle driving unit 5 and the center spindle driving unit 4. Upon winching off the driving units, when the relative distance L becomes larger than a set distance L0, the rotating speed of a winch drum 38 for hanging the outer driving unit 5 is reduced, and when the relative distance L becomes smaller than the set distance L0, the rotating speed of a winch drum 8 for hanging the center driving unit 4 is reduced, so that the relative distance L is kept in the set distance L0.
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