Abstract: An agricultural machine includes a frame, and a lifting unit configured to vary a height of an operating unit with respect to a supporting surface for the machine. The lifting unit includes hydraulic cylinder with a liner and first and second pistons both slidingly housed inside the liner and arranged in series to define first and second chambers inside the liner, wherein the first and second pistons are controllable independently. The lifting unit includes a pressure stabilizer in fluid connection with the first chamber and that controls a pressure in the first chamber so that the first piston moves therein as a force generated on the first piston varies. A second control element for the second chamber carries out a volumetric control of the second chamber to control a position of the second piston regardless of a pressure inside the second chamber.