Abstract: A pile driver arrangement including a reciprocal impact member connected to a piston rod which is also connected to a reciprocal piston located in a hydraulic cylinder having a lower rod end and an upper blind end. A hydraulic fluid tank and a pump for supplying hydraulic fluid from the tank to the lower rod end of the hydraulic cylinder to lift the piston and the impact member. A first hydraulic fluid conduit connecting the upper blind end of the hydraulic cylinder and the lower end of the hydraulic cylinder and a check valve to prevent the flow of hydraulic fluid from the lower end to the upper end of the hydraulic cylinder. A second hydraulic fluid conduit connecting the pump and the lower end of the hydraulic cylinder and a control valve in the second conduit for controlling the flow of hydraulic fluid from the pump to the lower end of the hydraulic cylinder.

Abstract: A vibratory pile driver having means for clamping onto a pile or similar structure to be driven or extracted substantially linearly, e.g. vertically, includes a hydraulic gear motor having two oppositely rotatable shafts and a pair of semicircular weights aligned in the same vertical plane. Each weight is rotatably secured to a shaft parallel to the motor shafts. Means, in the form of drive and driven pulleys, sprockets or the like connected by toothed timing belts, chains or the like, respectively, are provided for driving the weights from the motor shafts. Since the gears of the hydraulic gear motor operate in synchronization, the weights are driven synchronously to provide substantially linear, e.g. vertical, forces. Such an arrangement combines the synchronizing gears and the power source and makes it possible to eliminate relatively large gears, to use larger diameter weights and to achieve, under certain designs, a smaller overall machine width adjacent the pile to be driven.