| 摘要 |
PROBLEM TO BE SOLVED: To recover a mechanism member such as an excavation mechanism section. SOLUTION: An excavator has a propelling pipe 1 buried into a ground and an excavation mechanism section 2 being arranged on the front end side of the propelling pipe 1 and excavating an external ground at the front end of the propelling pipe 1. The excavation mechanism section 2 has a self-propelled mechanism section 3 being installed into the propelling pipe 1 longitudinally movably, detachably fixing the excavation mechanism section 2 at an arbitrary place in the propelling pipe 1 and moving the excavation mechanism section 2 in the longitudinal direction. The self-propelled mechanism section 3 has front and rear clamps 3a and 3b, in which a diameter expansion brought to a clamped state by a fast sticking on the internal surface of the propelling pipe 1 and a diameter reduction brought to an unclamped state by a separation from an internal surface are free, and an extensible jack 3c, and moves the excavation mechanism section 2 in a measuring worm shape by combining the clamped or unclamped state and the expansion-contraction operation of the jack 3c.
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