Abstract: A pile driver system for installing or removing foundation elements, such as piles, anchors, and conductors, in a subsea ground formation, includes a closed housing defining a cavity, an impact weight accommodated inside the housing, a hydraulic circuit for reciprocating the impact weight, which circuit comprises one or more valves, a cylinder, and a piston accommodated in the cylinder and connected to the impact weight, a pump for withdrawing water from the surroundings of the pile driver and providing pressurized water to the hydraulic circuit, and at least one outlet for returning water to the surroundings. The exhaust of the hydraulic circuit communicates with the cavity and the outlet is located in the wall of the housing.

Abstract: A pile driver system for installing or removing foundation elements, such as piles, anchors, and conductors, in a subsea ground formation, includes a closed housing defining a cavity, an impact weight accommodated inside the housing, a hydraulic circuit for reciprocating the impact weight, which circuit comprises one or more valves, a cylinder, and a piston accommodated in the cylinder and connected to the impact weight, a pump for withdrawing water from the surroundings of the pile driver and providing pressurized water to the hydraulic circuit, and at least one outlet for returning water to the surroundings. The exhaust of the hydraulic circuit communicates with the cavity and the outlet is located in the wall of the housing.

Abstract: The hammer of an underwater pile driving apparatus is movable upwards and downwards in a housing which, in operation, is filled with a liquid which is present both above and below the hammer, the hammer being driven at least on the upwards direction by a driving liquid which is pressurized by a motor driven pump located on or adjacent the housing and which is the same as the liquid in which the hammer moves.

Abstract: The combination of a pile driving apparatus having a hammer operating mechanism mounted above a downwardly extending pile sleeve having an internal cross-section dimensioned to receive the top of a pile of a first diameter, whereby the apparatus may be guided onto and supported on the top of a pile, with an adaptor fitted within the pile sleeve and having an internal cross-section dimensioned to receive the top of a pile of smaller diameter than said first diameter, said adaptor being fabricated as a unit and the adaptor unit and pile sleeve being interconnected preventing withdrawal of the adaptor unit from the pile sleeve.