Abstract: A hydraulic servo-control of a servo-controlled gearbox comprises hydraulic actuators defining chambers, a storing tank containing control fluid used by the actuators at room pressure, a hydraulic accumulator containing control fluid under pressure, a motor pump drawing the fluid from the tank and feeding it under pressure to the accumulator, and solenoid valves selectively connecting the chambers to the tank and accumulator. The accumulator includes an outer housing defining an inner cylindrical surface defining a first diameter, a piston arranged and axially slidable and mobile inside the housing and defining there a first variable-volume chamber for a gas and second variable-volume chamber for the fluid under pressure, and a limit stopper arranged at an open end of the housing, acting as a striker for the piston, and having an annular circlip defining an opening and overall second diameter approximating by excess the first diameter of the surface of the housing.

Abstract: A hydraulic servo-control of a servo-controlled gearbox provided with a hydraulic accumulator, having an outer housing and a piston that is slidable axially inside the outer housing and adapted to define a first variable-volume chamber for a gaseous material and a second variable-volume chamber for a control fluid under pressure; and at least one limit stop arranged at an open end of the outer housing which serve as a lower limit stop element; wherein the outer housing is provided with an upper limit stop element, which acts to limit the pressure value inside the first variable-volume chamber within a predetermined safety range.

Abstract: A hydraulic servo-control of a servo-controlled gearbox comprises hydraulic actuators defining chambers, a storing tank containing control fluid used by the actuators at room pressure, a hydraulic accumulator containing control fluid under pressure, a motor pump drawing the fluid from the tank and feeding it under pressure to the accumulator and solenoid valves selectively connecting the chambers to the tank and accumulator. The accumulator includes an outer housing, a piston arranged and axially slidable and mobile inside the housing and defining there a first variable-volume chamber for a gas and second variable-volume chamber for the fluid under pressure, and a limit stopper arranged at an open end of the housing, acting as a striker for the piston, and having an annular circlip and a perforated plate operatively interposed between the circlip and piston.

Abstract: A hydraulic servo-control of a servo-controlled gearbox provided with a hydraulic accumulator, having an outer housing and a piston that is slidable axially inside the outer housing and adapted to define a first variable-volume chamber for a gaseous material and a second variable-volume chamber for a control fluid under pressure; and at least one limit stop arranged at an open end of the outer housing which serve as a lower limit stop element; wherein the outer housing is provided with an upper limit stop element, which acts to limit the pressure value inside the first variable-volume chamber within a predetermined safety range.

Abstract: An actuation system for a servo-assisted transmission; the actuation system is provided with: a hydraulic circuit comprising a reservoir containing a control fluid, a hydraulic accumulator containing the pressurized control fluid, and a pump which draws from the reservoir and feeds the hydraulic accumulator; at least a hydraulic actuator comprising at least one actuation chamber and a mobile piston which slides within the actuation chamber; a solenoid valve for connecting the actuation chamber of the hydraulic actuator to the hydraulic accumulator and to the reservoir; and a recirculation circuit, which departs from at least one environment bordering with the actuation chamber of the hydraulic actuator and ends in the reservoir.

Abstract: An actuation system for a servo-assisted transmission; the actuation system is provided with: a hydraulic circuit comprising a reservoir containing a control fluid, a hydraulic accumulator containing the pressurized control fluid, and a pump which draws from the reservoir and feeds the hydraulic accumulator; at least a hydraulic actuator comprising at least one actuation chamber and a mobile piston which slides within the actuation chamber; a solenoid valve for connecting the actuation chamber of the hydraulic actuator to the hydraulic accumulator and to the reservoir; and a recirculation circuit, which departs from at least one environment bordering with the actuation chamber of the hydraulic actuator and ends in the reservoir.

Abstract: Unit for controlling the shaft for selection and engagement of gears, provided with a control shaft, which can be connected to the said shaft for selection and engagement of the gears, with a device for movement, which can impart to the shaft angular movements which are designed to implement the passage between two angular engagement positions of gears which belong to a single row, and with a cam-guide device, which can modify the said angular displacements, selectively by command, into combined axial and angular displacements, such as to implement the change of gear between consecutive gears which belong to consecutive rows; the cam-guide device being axially mobile along the control shaft, between a plurality of row-change positions, at each of which it can guide the control shaft in the said combined angular and axial displacement, which can implement the passage of gear between two consecutive gears which belong to two consecutive rows; the cam-guide device also being able selectively to use the angular d