A baler connectable to a tractor for providing round bales, comprising: - a frame supported on a wheel axle; - a chamber for receiving crops and for housing a formed bale, the chamber having a fixed, predetermined size; - a tailgate connected to the frame and movable between a closed position, for cooperating with the frame to delimit the chamber, and an open position, for discharging the formed bale; - a conveying assembly, which delimits the chamber for imparting a rotating movement to the crops contained in the chamber, and has a first portion provided in the frame and a second portion provided in the tailgate; - a cylinder-piston actuator, which includes a closing chamber and is connected to the frame and to the tailgate to move the tailgate from the open position to the closed position, upon receiving an actuating fluid in the closing chamber; - a binder, configured for binding the formed bale with a fastening element; - a control unit, configured to generate an alert signal, - a pressure sensor for detecting a control signal representative of a pressure inside the closing chamber of the cylinder-piston actuator, wherein the control unit is programmed for generating the alert signal as a function of the control signal, wherein the cylinder-piston actuator is a double effect actuator, which includes, further to the closing chamber, an opening chamber, which can be fed with the actuating fluid for commanding a movement of the tailgate from the closed position to the open position, wherein the cylinder-piston actuator is a hydraulic actuator and wherein the baler comprises a hydraulic circuit including: - a first conduit and a second conduit, which are selectively connectable to a pressure source and are in fluid communication with the closing chamber and with the opening chamber of the cylinder-piston actuator, respectively, characterized in that the hydraulic circuit includes: - a setting valve which is connected between the first conduit and the second conduit and is configured to allow a flow of the actuating fluid from the first conduit to the second conduit, when a first pressure in the first conduit exceeds a second pressure in the second conduit of a predetermined first threshold value; - a safety valve which is connected between the first conduit and the second conduit and is configured to allow a flow of the actuating fluid from the first conduit to the second conduit, when the first pressure in the first conduit exceeds the second pressure in the second conduit of a predetermined second threshold value, wherein the second threshold value is higher than the first threshold value. - a frame supported on a wheel axle; - a chamber for receiving crops and for housing a formed bale, the chamber having a fixed, predetermined size; - a tailgate connected to the frame and movable between a closed position, for cooperating with the frame to delimit the chamber, and an open position, for discharging the formed bale; - a conveying assembly, which delimits the chamber for imparting a rotating movement to the crops contained in the chamber, and has a first portion provided in the frame and a second portion provided in the tailgate; - a cylinder-piston actuator, which includes a closing chamber and is connected to the frame and to the tailgate to move the tailgate from the open position to the closed position, upon receiving an actuating fluid in the closing chamber; - a binder, configured for binding the formed bale with a fastening element; - a control unit, configured to generate an alert signal, - a pressure sensor for detecting a control signal representative of a pressure inside the closing chamber of the cylinder-piston actuator, wherein the control unit is programmed for generating the alert signal as a function of the control signal, wherein the cylinder-piston actuator is a double effect actuator, which includes, further to the closing chamber, an opening chamber, which can be fed with the actuating fluid for commanding a movement of the tailgate from the closed position to the open position, wherein the cylinder-piston actuator is a hydraulic actuator and wherein the baler comprises a hydraulic circuit including: wherein the cylinder-piston actuator is a double effect actuator, which includes, further to the closing chamber, an opening chamber, which can be fed with the actuating fluid for commanding a movement of the tailgate from the closed position to the open position, wherein the cylinder-piston actuator is a hydraulic actuator and wherein the baler comprises a hydraulic circuit including: - a first conduit and a second conduit, which are selectively connectable to a pressure source and are in fluid communication with the closing chamber and with the opening chamber of the cylinder-piston actuator, respectively, - a setting valve which is connected between the first conduit and the second conduit and is configured to allow a flow of the actuating fluid from the first conduit to the second conduit, when a first pressure in the first conduit exceeds a second pressure in the second conduit of a predetermined first threshold value; - a safety valve which is connected between the first conduit and the second conduit and is configured to allow a flow of the actuating fluid from the first conduit to the second conduit, when the first pressure in the first conduit exceeds the second pressure in the second conduit of a predetermined second threshold value, wherein the second threshold value is higher than the first threshold value.