Abstract: The device embodying the invention uses a phase shifter controlled by a dual-effect hydraulic acting element comprising a phase shifting chamber connected to the distributor output via a circuit comprising a nonreturn valve and a hydraulic accumulator whose load pressure can be limited by means of a limiter and a rephasing chamber whose pressure is controlled by a pressure regulator so that a predetermined phase shift corresponds with each regulator control value. The invention applies notably to the driving into the ground of objects such as stakes or sheet piles.

Abstract: A vibrator has two series of eccentric weights each comprising at least two weights turning in opposite directions and at least one motor coupled to the first series of weights by gearing and to the second series of weights by a transmission device including a phase-shifter in the form of two coaxial shafts each comprising helical teeth and an annular piston which slides between the two shafts, delimiting therewith at least one working chamber into which a pressurized hydraulic fluid can be injected. The piston has helical teeth meshing with those on the two shafts. The vibrator enables self-regulation of the amplitude of the vibrations that it produces according to the behavior of the object to which the vibrations are imparted.