| 摘要 |
PROBLEM TO BE SOLVED: To bore a very small diameter hole by providing a drive device for rotating a blade part in a pipe jacking machine, providing a pressure jetting pipe supplying slurry on the circumference of the blade part, and making the body inside an earth removing passage. SOLUTION: When a hydraulic motor is driven, a rotary shaft 4 is rotated to rotate a blade part 3, ground is excavated by a blade 3a, and water or slurry of high pressure is supplied from a water pressure jetting pipe 11 on the circumference of the blade 3a. Excavated muddy soil is carried to the inside of an excavator body 2a to be carried rearward. When the pressure of the muddy soil is higher than prescribed air pressure of the inside of an air valve 10, the air pressure of the valve 10 is lowered to enlarge a passage area between a cover 6 and the valve 10 so as to carry the muddy soil rearward. In addition, when the pressure of the muddy soil is lower than the prescribed air pressure, the air pressure of the valve 10 is heightened to lessen the passage area so as not to carry the muddy soil rearward. The muddy soil carried rearward is agitated by an agitator 14 and carried to the outside by a discharge device 15. Thereby boring of a small diameter hole can be performed.
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