| 摘要 |
PURPOSE: To improve operability in weak ground by making the projection length of the pin of a ram boring machine smaller than the maximum stroke of a cutter in a striking direction, with a casing end driven into a main casing in the ram boring machine. CONSTITUTION: A collar 14 on a cutter 10 is disposed in a casing hole 13 and brought into contact with a rear stop 15, and the pin 16 of the cutter 10 is projected into the working chamber 17 of a striking pin 3 in a thread extension 7 at a casing end 6. A projection length 18 of the pin 16 is made smaller than a maximum stroke 19, over which the cutter collar 14 advances in striking direction 4 from the rear stop 15 position to a pin 12 which limits a front stop 20. After the cutter 10 has advanced a distance corresponding to the projection length 18, a striking piston 3 collides completely with the front 21 of the casing end 6 to prevent further advance of the cutter 10. Generation of repulsive impacts by the striking energy of the striking piston 3 in weak ground can thus be avoided. |
