A baler (1) connectable to a tractor (2) for providing round bales comprises: a frame (3) supported on a wheel (4) axle； a chamber (5), for receiving crops and for housing a formed bale, the chamber having a fixed, predetermined size； a tailgate (6) connected to the frame and movable between a closed position, for cooperating with the frame (3) to delimit the chamber (5), and an open position, for discharging the formed bale； a conveying assembly, which delimits the chamber (5) for imparting a rotating movement to the crops contained in the chamber (5), and has a first portion provided in the frame (3) and a second portion provided in the tailgate (6)； a cylinder-piston actuator (7), which includes a closing chamber (701) and is connected to the frame (3) and to the tailgate (6) to move the tailgate (6) from the open position to the closed position, upon receiving an actuating fluid in the closing chamber (701)； a binder (12), configured for binding the formed bale with a fastening element； a pressure sensor (P1) for detecting a control signal representative of a pressure inside the closing chamber (701) of the cylinder-piston actuator (7)； a control unit, configured to generate an alert signal as a function of the control signal.
