EXTENSION AND CONTRACTION DEVICE FOR INNER DIGGER ROD

摘要

PROBLEM TO BE SOLVED: To provide a device capable of rotating and driving an inner digger rod inserted into a hollow pile by the same driving source as that of the pile. SOLUTION: A casing 7 for rotating the pile for connecting the hollow pile 11 with a lower end and a rotary body 8 for rotating the inner digger rod are rotatably supported in a driving part 2 hoisted and held along a leader mast so as to elevate and lower freely in a drivable manner, respectively. The rotary body 8 supports one ends of a plurality of hydraulic cylinders 16 and connects a cylindrical outer cylinder 24 with the other ends of the hydraulic cylinders. It allows a cylinder bundling member 7 bundling the hydraulic cylinders and the outer cylinder to slide in the axial direction and is fitted in the direction of rotation to rotate integrally. Upper and lower liquid medicine passages 20, 23 provided in a central part of the cylinder bundling member and a central part of the outer cylinder and provided to communicate with a liquid medicine passage of the inner digger rod are mutually connected slidably in the axial direction. Pressure oil is uniformly supplied into and discharged from the plurality of hydraulic cylinders to expand and contract the inner digger rod 1 in the vertical direction. COPYRIGHT: (C)2005,JPO&NCIPI