Actuation unit of the articulated lever or cam type comprising - an actuating arm pivotable between an open position and an operative closed position; - a pneumatic cylinder comprising a stem movable linearly along a cylinder axis and operatively connected to the actuating arm to control the movement of the actuating arm between the open position and the operative closed position; - a closing device functionally interposed between the pneumatic cylinder and the actuating arm and configured to bring the actuating arm into rotation following a translational movement imparted by the pneumatic cylinder, wherein the closing device comprises a mechanism of irreversibility of movement configured to trigger when the actuating arm reaches the operative closed position; and - a braking unit configured to brake and/or stop the movement of the actuating arm, the braking unit comprising - a threaded shaft comprising a first end operatively coupled to the stem of the pneumatic cylinder in such a way that a translation of the stem determines a rotation of the threaded shaft, and a second end provided with a head portion comprising at least one surface portion configured to come into contact with at least one braking assembly; and - a braking assembly locked against rotation and axially movable relative to the head portion of the threaded shaft between a first non-braking configuration in which the braking assembly is not in contact with the at least one surface portion of the head portion and a second braking configuration in which the braking assembly is in contact with the at least one surface portion of the head portion; characterized in that the at least one surface portion of the head portion configured to come into contact with the braking assembly is in a non-orthogonal arrangement with respect to the axis of the cylinder and in that the braking assembly comprises plurality of rollers retained in the braking assembly with clearance at least with respect to a radial movement thereof, the rollers of the plurality of rollers being able to assume a first radial configuration not in contact with the at least one surface portion of the head portion and a second radial configuration in contact with the at least one surface portion of the head portion. - an actuating arm pivotable between an open position and an operative closed position; - a pneumatic cylinder comprising a stem movable linearly along a cylinder axis and operatively connected to the actuating arm to control the movement of the actuating arm between the open position and the operative closed position; - a closing device functionally interposed between the pneumatic cylinder and the actuating arm and configured to bring the actuating arm into rotation following a translational movement imparted by the pneumatic cylinder, wherein the closing device comprises a mechanism of irreversibility of movement configured to trigger when the actuating arm reaches the operative closed position; and - a braking unit configured to brake and/or stop the movement of the actuating arm, the braking unit comprising - a threaded shaft comprising a first end operatively coupled to the stem of the pneumatic cylinder in such a way that a translation of the stem determines a rotation of the threaded shaft, and a second end provided with a head portion comprising at least one surface portion configured to come into contact with at least one braking assembly; and a first end operatively coupled to the stem of the pneumatic cylinder in such a way that a translation of the stem determines a rotation of the threaded shaft, and a second end provided with a head portion comprising at least one surface portion configured to come into contact with at least one braking assembly; and - a braking assembly locked against rotation and axially movable relative to the head portion of the threaded shaft between a first non-braking configuration in which the braking assembly is not in contact with the at least one surface portion of the head portion and a second braking configuration in which the braking assembly is in contact with the at least one surface portion of the head portion;