Abstract: A pile hammer for driving down hollow piles from an upper end thereof includes a hollow pile cap adapted to rest and support the hammer on a upper end of the pile being driven. The cap has an anvil surface for receiving blows from a ram which is slidably disposed on a hollow tubular base extending downwardly from the pile cap and having a lower end portion extending into the hollow pile being driven below the level of the pile cap. The ram is slidable on an upper portion of the hollow tubular base and has an annular lower end face adapted to strike the anvil surface of the pile cap when the ram is released to drop from an elevated position above the pile cap. A ram lift system is provided in an upper portion of the hollow tubular base for lifting the ram to an elevated position a selected predetermined height above the pile for release to drop downwardly and strike a driving blow against the anvil surface on the pile cap.

Abstract: A vibratory hammer/extractor for use with elongated pilings and the like extended into the earth includes a clamping assembly for releasing and securing the hammer to an upper end portion of a piling extended into the ground. A vibratory exciter is mounted on the clamping assembly for generating vibratory forces to be imparted to the piling while clamped tightly, and a suspension device is provided for supporting the exciter and isolating the vibration thereof from a hammer supporting element such as a flexible cable extending downwardly from the boom of a crane. The vibratory exciter includes a hollow gear case having a lower end wall secured to the clamping assembly and at least one pair of eccentric weights mounted on shafts for rotation about an axis transversely of the clamped piling for imparting vibratory forces to the piling as the eccentrics are driven in rotation.

Abstract: A retaining assembly for retaining a key or the like within a slot that is defined in a housing includes a bar secured to the key. The bar includes an aperture through which passes a first end of a threaded rod. The rod includes a second end that is adapted to abutt against the housing. Threaded on the rod between the housing and the bar is a nut that may be threaded to bear against the bar producing a force against the bar that is transmitted to the key to prevent the key from sliding out of the slot. In the preferred embodiment, the slot and key are tapered.

Abstract: An assembly for tensioning cables on a percussion hammer or the like wherein each cable has a threaded end fitting. The assembly includes a lock nut threadably mounted on the end fitting for locking the end fitting relative to the hammer. Also included in the assembly is a jacking sleeve threadably mounted on the end of the cable fitting and adjacent to the nut. A hydraulic jack body is mounted around the jacking sleeve and nut and abuts a portion of the hammer at one end thereof. The jack body includes a hydraulic cylinder and piston wherein the piston is mechanically connected to the jacking sleeve by a split ring. Movement of the piston due to the introduction of hydraulic fluid into the chamber imparts a corresponding movement to the jacking sleeve resulting in tensioning of the cable.

Abstract: There is provided an improved percussion hammer having tie cables connecting the base of the hammer body with the upper cylinder. Cable tensioning jacks are used for preloading the tie cables. Each cable tensioning jack includes a jack body having a central opening for securing a cable, and having an annular groove defining a jack cylinder closed at one end and open at the other. An annular jack piston is slidably received within the jack cylinder. The annular cylinder is pressurized to expand the jack. In one embodiment of the invention high pressure grease provides the source of pressurized fluid.