Abstract: A portable hydraulic actuated machine for driving posts, ground anchors, concrete breakers, core drills and the like work pieces into the ground, pavements, or wall structures, maintains a continuing thrust on the work piece amplified by sequential hammer blows of controlled magnitude to advance the work piece at a rapid rate without damage to the impact receiving end of the work piece. The machine includes an automotive vehicle which is easily transported to the work site and which carries a turntable supporting an upstanding tower on which rides a carriage slidably mounting a spring loaded heavy hammer, a work piece engaging spring loaded anvil struck by the hammer and hydraulical hammer lifting mechanism. The tower is easily raised and lowered, adjusted toward and away from the vehicle and tiltable laterally to present the hammer and anvil to the work piece at the exact desired location in the plane of the work piece.

Abstract: The pile-driving arrangement can drive piles both above and below water. It includes a housing containing a gas-filled motion chamber and an impact body movable upward and downward in the motion chamber. A cylinder-and-piston mover includes a cylinder part and a piston part, one part connected with the housing and the other with the impact body, for effecting relative movement between the impact body and the housing. A drive unit on the housing includes a drive motor, a pump driven by the motor and a pressure fluid tank. The drive unit is connected with the housing for limited movement relative to the housing. The cylinder part and the pressure fluid pump are interconnected by flexible conduits leading from the pump to the opposite working chambers of the cylinder part, and a direction-changing device controls fluid flow through the conduits.

Abstract: A hammer assembly comprising a housing having opposing open ends and an internal passage extending between the open ends. A hammer element is positioned in the housing for reciprocal movement in the passage between first and second positions. The hammer element has an opening formed therein in which a biasing member is positioned. When enabled, the biasing member is capable of biasing the hammer element in a desired direction relative to the first and second positions. Means are also included for enabling the biasing member when the hammer element is in at least its first position. The housing is desirably fabricated of a self-lubricating material with the area of the opening at one of its ends substantially larger than the cross-sectional area of the hammer element, taken along a plane perpendicular to the axis of motion of the hammer element at such one end in order for air to be freely vented from the passage during reciprocal movement of the hammer assembly.

Abstract: The post driver apparatus of the instant invention is designed to be mounted on a truck chassis that can be readily moved from site to site and comprises a fluid-pressure impact hammer mounted in a shock absorbing cage assembly that permits rapid driving of posts into the ground without transmission of substantial shock forces to the frame and chassis on which the post driver is mounted. The apparatus is also equipped with means to vary the location and orientation of the impact hammer with respect to the truck chassis thereby minimizing the precision with which the truck chassis must be located.