| 摘要 |
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 15 that includes a mechanism for rotating a leader 17. The leader revolver 15 includes a fixed-side outer tube 31 and a rotation-side inner tube 32 that is concentrically arranged inside the fixed-side outer tube 31 via a pair of tapered roller bearings 35, 36 provided at two upper and lower positions. A lower part of the leader 17 is connected, in an integrally rotatable state, to an upper part of the rotation-side inner tube 32 protruding upward from an upper end opening of the fixed-side outer tube 31. A hydraulic motor 33 is placed in a lower part of the leader revolver 15. One of a fixed flange 61 and a movable flange 62 of the hydraulic motor 33 is connected to a lower part of the rotation-side inner tube 32, and the other flange is connected to a lower part of the fixed-side outer tube 31.
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