Abstract: Method and device for driving a pile (5) into and out of the ground. The device comprises a hammer (2) provided with a bush (8) protruding away from the hammer in an axial direction and being supported by the hammer and rotatable in relation thereto by remote control means (10). The inner surface of the bush (8) and the pile (5) to be extracted from the ground have been provided with locking dogs (11, 12 respectively). The bush (8) can be partially shoved and rotated onto the pile (5) in an axial direction, so that the top plane of the dogs (11) connected to the bush will come to lie beneath the bottom plane of the locking dogs (12) connected to the pile (5). Thereafter, the pile (5) can be driven out of the ground.

Abstract: Method for driving a hydraulic submerged tool whereby the hydraulic pressure energy is generated in a submerged power converter, being driven by pressurized surrounding water which after the energy transfer is exhausted into the surrounding water, said power converter consisting of one or more work cylinders (1, 2), each by means of a floating piston (3, 4) being divided in a space (5, 6) filled with the pressurized surrounding water and a space (7, 8), filled with a hydraulic work medium, switching means (17, 18) being provided, for alternately connecting said space (5, 6) either to a feed conduct (13) for pressurized surrounding water, or to an exhaust (14).

Abstract: Device for withdrawing a pile or the like which has been driven into the soil by a ram device which can perform blows downwardly and upwardly and which in upward direction has a lost-motion connection with the pile, which lost motion for efficient withdrawal is removed by the extension of hydraulic cylinders.

Abstract: A hydraulic pile driver including a housing having an impact weight mounted therein for reciprocating movement, the impact weight being fastened to a piston movable in a cylinder, a supply source for liquid under pressure, a supply conduit communicating with the supply source, a liquid discharge conduit, a control valve for alternatively connecting the supply and discharge conduits to a cylinder chamber at one side of the piston, whereby the piston can be moved by the liquid under pressure in a direction opposite to the direction of movement of the impact weight during the work stroke, the cylinder chamber during the work stroke of the impact weight being connected to the liquid discharge conduit. The piston at the side remote from the cylinder chamber is loaded by a second pressure medium, the overpressure of the second pressure medium being low with respect to the liquid pressure in the cylinder chamber prior to the working stroke, the overpressure being independent of the liquid pressure.