Variable displacement hydraulic pump

Control system for a hydraulic pump in which the pump is provided with a displacement variation apparatus, the system comprising a control device for variation of displacement provided with a servo-control device with a cylinder and a piston provided with connection means to the displacement variation apparatus of the pump, the cylinder comprising a first semi-portion and a second semi-portion separated by the piston for delivery of a fluid under pressure for movement of the piston respectively in a first movement direction and in a second movement direction opposite to the first direction, the system comprising a control unit, a driving valve and a first solenoid and a second solenoid for control of the valve, the control unit comprising a displacement increase input and a displacement decrease input, a first output connected to the first solenoid and a second output connected to the second solenoid wherein the valve includes a body provided with conduits for delivery of the fluid alternatively in the first semi-portion or in the second semi-portion of the cylinder, the valve comprising a spool which is movable within a seat between at least three positions, a neutral position for blocking the fluid flow towards the cylinder, a first position for delivery of the fluid to the first semi-portion of the cylinder, a second position for delivery of the fluid to the second semi-portion of the cylinder, the spool being connected to an elastic element for return to the neutral position, the first solenoid and the second solenoid being current controlled solenoids, the system comprising a position detection device of the servo-control device for position feedback of the real position of the servo-control device, the control unit comprising a logic for current control of first output and second output with a dependency on the feedback of the position detection device, wherein the position detection device of the servo-control device comprises a pin which is connected to the servo-control device by means of a lever in such a way that a movement of the pin corresponds to a movement of the servo-control device, the elastic element for return to the neutral position being applied between a couple of arms provided with a fulcrum point, the spool being provided with an engagement element with the couple of arms for movement integral with the spool of at least one between the arms of the couple of arms and wherein the pin is in a contact condition with said couple of arms so that a movement of the pin corresponds to a movement of the piston of the servo-control device with corresponding increase of reciprocal distance of the couple of arms according to the position of the servo-control device, said reciprocal distance of the couple of arms by means of said pin constituting said position feedback of the real position of the servo-control device.