Tamping machine, particularly for regenerating railway ballasts, comprising: - at least one supporting frame associable above at least one railway track, said railway track being of a type comprising at least two rails and a plurality of sleepers, - at least one tamping hammer extending along a prevalent development direction between an operative portion and a thrusting portion, the tamping hammer comprising an engaging portion, interposed between the operative portion and the thrusting portion, pivoted to the frame and suitable for enabling the hammer to rotate with respect to the frame, the tamping hammer being configured for being arranged in a working condition wherein the hammer is beside a track between a sleeper and an immediately following one along the track, the hammer, in the working condition, being configured for being transversally arranged to the rails and to the sleepers, particularly vertically to the ballast, with the operative portion facing said ballast, the tamping hammer being further configured for being arranged at least in an exclusion or receiving condition wherein the hammer is substantially positioned horizontally or in a sloped position with respect to the working position suitable for defining a starting position for tamping the sleeper, - at least a hydraulic actuator engaged, on a side, with the thrusting portion of the tamping hammer and, on the other side, with an abutment portion, the actuator comprising at least one first and one second sections (5, 6) axially aligned and engaged with each other, one of said first and second sections (5, 6) being engaged with the abutment portion while the other being engaged with the thrusting portion of the tamping hammer, the first section being extendable and configured for moving the hammer at least between the working condition and the receiving or exclusion condition, and vice versa, the second section being configured for being powered by distributing means having cyclic alternating functioning for enabling the tamping hammer to vibrate, characterized by the fact that the second section comprises at least one jacket extending between a first and second longitudinal ends (7a, 7b) and at least one piston slidingly moveable inside the jacket, the jacket being closed at the first and second longitudinal ends (7a, 7b), the piston having an overall axial size defined by respective opposite thrusting faces of the piston itself, which is entirely contained inside the jacket, wherein the second section comprises at least one connecting element stably constrained to and transversally emerging from the piston of the second section itself, the jacket of the second section comprising at least one longitudinal through groove arranged on a lateral wall of said jacket between the first and second longitudinal ends (7a, 7b) of the same, the connecting element of the piston passing through and being slidingly axially engaged inside the longitudinal groove, and wherein the jacket of the first section comprises at least one anchoring portion engaged with the connecting element of the second section, the jacket of the first section being, with the piston and connecting element of the first section, relatively movable with respect to the jacket of said second section. - at least one supporting frame associable above at least one railway track, said railway track being of a type comprising at least two rails and a plurality of sleepers, - at least one tamping hammer extending along a prevalent development direction between an operative portion and a thrusting portion, the tamping hammer comprising an engaging portion, interposed between the operative portion and the thrusting portion, pivoted to the frame and suitable for enabling the hammer to rotate with respect to the frame, the tamping hammer being configured for being arranged in a working condition wherein the hammer is beside a track between a sleeper and an immediately following one along the track, the hammer, in the working condition, being configured for being transversally arranged to the rails and to the sleepers, particularly vertically to the ballast, with the operative portion facing said ballast, the tamping hammer being further configured for being arranged at least in an exclusion or receiving condition wherein the hammer is substantially positioned horizontally or in a sloped position with respect to the working position suitable for defining a starting position for tamping the sleeper, - at least a hydraulic actuator engaged, on a side, with the thrusting portion of the tamping hammer and, on the other side, with an abutment portion, the actuator comprising at least one first and one second sections (5, 6) axially aligned and engaged with each other, one of said first and second sections (5, 6) being engaged with the abutment portion while the other being engaged with the thrusting portion of the tamping hammer, the first section being extendable and configured for moving the hammer at least between the working condition and the receiving or exclusion condition, and vice versa, the second section being configured for being powered by distributing means having cyclic alternating functioning for enabling the tamping hammer to vibrate, characterized by the fact that the second section comprises at least one jacket extending between a first and second longitudinal ends (7a, 7b) and at least one piston slidingly moveable inside the jacket, the jacket being closed at the first and second longitudinal ends (7a, 7b), the piston having an overall axial size defined by respective opposite thrusting faces of the piston itself, which is entirely contained inside the jacket,