PURPOSE: To cope with a plurality of methods of construction by the same device by juxtaposing a planet gear row to the rotary driving device of a casing tube and installing a kelly-bar and a torque transmission gear, which can be engaged, as required to an internal gear.
CONSTITUTION: When a method of all casing construction is carried out, a casing tube 21 is fixed to a clamp 4, and internal soil and sand are excavated and removed by a hammer grab while the casing tube 21 is rotated and pushed in. When a method of earth drill construction is executed, the clamp 4 is loosened, and a bucket is hung by a kelly-bar 16, and inserted into a rotary driving device 3. Consequently, a yoke 17 is intruded from an upper section and engaged with stoppers 14, revolving torque is transmitted in order of an internal gear, the stoppers 14, the yoke 17, the kelly-bar 16 and the bucket, and excavation is conducted. When a method of reverse circulation drill construction is performed, the casing tube 21 is fixed to the clamp 4, a drill pipe 22 is connected at the lower end of the kelly-bar 16, a wing bit 23 is 1 rotated at high speed through a planet gear, and excavation is moved forward.
NARAHARA TOSHIAKI
MIZUTA SADACHIKA
