Patent attributes
A pile driver includes a leader rotation/holding mechanism that can firmly hold a leader in a rotatable state and also reliably rotate the leader using a general-purpose, inexpensive hydraulic motor by keeping the hydraulic motor from action of a bending moment from the leader. The pile driver has a leader revolver that includes a mechanism for rotating a leader. The leader revolver includes an outer tube and an inner tube that is concentrically arranged inside the outer tube via a pair of tapered roller bearings provided at two upper and lower positions. A lower part of the leader is connected, in an integrally rotatable state, to an upper part of the inner tube protruding upward from an upper end opening of the outer tube. A hydraulic motor is placed in a lower part of the leader revolver.
