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(11) | EP 0 276 845 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Pile driver |
(57) The present invention provides a pile driver comprising a vibration cylinder (3)
and a self-equilibration cylinder (7) so provided vertically in series with each other
that the axes of their respective rods lie on the center line passing through the
center of gravity of an inertial weight (1), the rods of the vibration and self-equilibration
cylinders being coupled to each other, the vibration cylinder having provided therein
a changeover valve (10) to supply and discharge a pressurized fluid to and from the
vibration cylinder, the self-equilibration cylinder having provided therein a control
valve (11) responsive to the rod of either the self-equilibration cylinder or vibration
cylinder to supply and discharge the pressurized fluid to and from a control chamber
in the self-equilibration cylinder. The piston of the self-equilibration cylinder
is supported with a low rigidity to the inertial weight by means of accumulators (14)
provided as communicating with the control chambers in the self-equilibration cylinder,
and also the self-equilibration cylinder or vibration cylinder has provided at the
lower end of the rod thereof a chuck (17) which grasps the pile. |