The machine (1) has a transverse beam (2) supporting a working tool (3), a reference element (4) and a leveling board (5) extending between the working tool and the reference element. Height of the leveling board is adjusted with respect to the working tool. The leveling board includes a control bar (10) actuated by an adjusting device (12) to carry out centralized height adjustment of the board. A transform unit (11) transforms movement of rotation of the control rod into translation motion of the leveling board. The bar includes length equal to width of the machine.
