| 摘要 |
A pipe is installed between a pointed front section and a rear section of a tool, and the rear section is subjected to a drive force in the longitudinal direction, so that the pointed section and the pipe is pushed into loosely packed materials. In response to an inadvertent hindrance in the loosely packed materials, the tool and the pipe connected thereto is pulled back by exerting a tractive force on a line connected to the pointed front section and running through the pipe and rear section. |
