An agricultural machine comprising: - a frame; - at least one operating unit connected to the frame; - at least one wheel or crawler track rotatably attached to the frame to allow the movement of the machine on a supporting surface; - a lifting unit operatively interposed between the frame and the wheel or between the frame and the operating unit, configured to adjust the height of the operating unit with respect to said supporting surface of the machine; wherein said lifting unit comprises at least one hydraulic cylinder provided with: a liner; a first and a second piston both slidingly housed inside the liner and arranged in series to define at least a first and a second chamber inside the liner; said first and second piston are controllable independently of each other, wherein the agricultural machine comprises a control circuit provided with: a first control element for the first chamber that can be switched between an active configuration, in which it maintains the pressure inside the first chamber around a predetermined value, and a passive configuration, in which the first chamber is substantially unloaded, wherein in said active configuration the first control element is configured to control the pressure in the first chamber, in order to allow fluid to enter the first chamber when the pressure therein falls below a predetermined value and to exit the first chamber when the pressure therein rises above said predetermined value so that the first piston move as the force generated on said first piston varies, and a second control element for the second chamber configured to carry out a volumetric control of the second chamber in order to control the position of the second piston regardless of the pressure inside said second chamber, wherein said second control element can be switched between an active configuration, in which it controls the second piston by moving it towards or holding it in a predefined position, and a passive condition, in which the second chamber is substantially unloaded and wherein said first control element of the first chamber comprises at least one pressure stabilising valve. - a frame; - at least one operating unit connected to the frame; - at least one wheel or crawler track rotatably attached to the frame to allow the movement of the machine on a supporting surface; - a lifting unit operatively interposed between the frame and the wheel or between the frame and the operating unit, configured to adjust the height of the operating unit with respect to said supporting surface of the machine; a liner; a first and a second piston both slidingly housed inside the liner and arranged in series to define at least a first and a second chamber inside the liner; said first and second piston are controllable independently of each other, wherein the agricultural machine comprises a control circuit provided with: a first control element for the first chamber that can be switched between an active configuration, in which it maintains the pressure inside the first chamber around a predetermined value, and a passive configuration, in which the first chamber is substantially unloaded, wherein in said active configuration the first control element is configured to control the pressure in the first chamber, in order to allow fluid to enter the first chamber when the pressure therein falls below a predetermined value and to exit the first chamber when the pressure therein rises above said predetermined value so that the first piston move as the force generated on said first piston varies, and a second control element for the second chamber configured to carry out a volumetric control of the second chamber in order to control the position of the second piston regardless of the pressure inside said second chamber, wherein said second control element can be switched between an active configuration, in which it controls the second piston by moving it towards or holding it in a predefined position, and a passive condition, in which the second chamber is substantially unloaded and wherein said first control element of the first chamber comprises at least one pressure stabilising valve. a first control element for the first chamber that can be switched between an active configuration, in which it maintains the pressure inside the first chamber around a predetermined value, and a passive configuration, in which the first chamber is substantially unloaded, wherein in said active configuration the first control element is configured to control the pressure in the first chamber, in order to allow fluid to enter the first chamber when the pressure therein falls below a predetermined value and to exit the first chamber when the pressure therein rises above said predetermined value so that the first piston move as the force generated on said first piston varies, and a second control element for the second chamber configured to carry out a volumetric control of the second chamber in order to control the position of the second piston regardless of the pressure inside said second chamber, wherein said second control element can be switched between an active configuration, in which it controls the second piston by moving it towards or holding it in a predefined position, and a passive condition, in which the second chamber is substantially unloaded and wherein said first control element of the first chamber comprises at least one pressure stabilising valve.