| 摘要 |
PURPOSE: To shorten a construction period and reduce a cost by recovering a machine body to the starting shaft side easily under and reusable state through a laid pipe without requiring a shaft for recovering the machine body. CONSTITUTION: A cutter head 3 with an expansion-contraction mechanism 3a is installed to an excavator body 2 internally inserted at the front end section of the buried pipe 15 while a plurality of grippers 31, 32, 41 and 42 for fixing and holding the excavator body 2 are disposed, and shoes 33 and 43 are constituted in a freely contact-bonding and releasing manner to the internal surface of the buried pipe 15 by the diameter expansion-contraction operation of these grippers 31, 32, 41 and 42.
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