| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent backing without executing work such as an anchor to a propulsion tube. <P>SOLUTION: In a gap formed between an inclined surface 12bs of a receiving base 12b of a backing prevention device 12 and an outer periphery of a propulsion tube 8, a wedge-shaped stopper 12c integrally connected with the receiving base 12b by a bolt 12bb and a nut 12bn is arranged. When extending the propulsion tube 8, the stopper 12c is pushed into the gap between the receiving base 12b and the propulsion tube 8 by fastening the nut 12bn, and the stopper 12c is moved to the side of the propulsion tube 8 to press the propulsion tube 8. When performing propulsion construction, by loosening the nut 12bn to separate the stopper 12c from the propulsion tube 8, the propulsion construction is performed without hindrance. <P>COPYRIGHT: (C)2013,JPO&INPIT |
