SELF-PRESSURE SWITCHING VALVE AND LEADING BODY OF PROPULSION UNIT FOR GROUND BORER HAVING THE SELF- PRESSURE SWITCHING VALVE

摘要

PROBLEM TO BE SOLVED: To make a leading body of a propulsion unit for a ground borer in a small size and with a small diameter by utilizing excavating water for leveling soil to rock a rocking head to dispense with hydraulic devices such as an oil pressure tank and a hydraulic pump for operating a rocking cylinder and electric devices such as an electric wire and an electric motor which have been provided heretofore, so that a mechanism part for operating the rocking cylinder is simplified.;SOLUTION: This leading body of the propulsion unit for the ground borer is provided with a leading body main body 1 of a rotating and advancing propulsion unit for the ground borer, the rocking head 2 fitted to the main body 1 of the leading body 1 to freely rock and having an inclined pressure receiving surface 14 and an injection nozzle 16 for injecting fluid for excavation, the rocking cylinder 4 for rocking the rocking head 2, and a self-pressure switching valve 5 switched between one side and the other side switching positions by pressure of the inflow excavating water, and adapted to operate the rocking cylinder 4 by supplying excavating water to the desired side of the rocking cylinder 4.;COPYRIGHT: (C)2002,JPO