Device for moving a leaf door, consisting of an electric motor , a reduction gear box and a crown wheel-pinion transmission system , wherein the electric motor is kinematically connected to the reduction gear box , which in turn is kinematically connected to the crown wheel-pinion transmission system , wherein the reduction gear box comprises a worm screw and a helical toothed wheel, wherein the worm screw is kinematically connected in a rotationally fixed manner to a shaft of the electric motor, the helical toothed wheel is coupled to the worm screw and is kinematically connected in a rotationally fixed manner to an output shaft of the reduction gear box , wherein the crown wheel-pinion transmission system comprises a toothed pinion and a toothed crown wheel that are kinematically connected to each other by means of a roller chain , wherein the toothed pinion is kinematically connected in a rotationally fixed manner to the output shaft of the reduction gear box , and the toothed crown wheel is kinematically connected in a rotationally fixed manner to an output shaft of the moving device , characterized in that the reduction gear box has a reduction ratio R', defined as the ratio between the rotational speed ω1 of the motor shaft and the rotational speed ω2 of the output shaft of the reduction gear box , between 10:1 and 20:1 and is reversible, in that the crown wheel-pinion transmission system has a reduction ratio R", defined as the ratio between the rotational speed ω2 of the output shaft of the reduction gear box and the rotational speed ω3 of the output shaft of the moving device , between 4:1 and 6:1, and in that the chain of the crown wheel-pinion transmission system has a pitch between 6 mm and 8 mm and the toothed pinion has a number of teeth (z2) equal to 8. wherein the reduction gear box comprises a worm screw and a helical toothed wheel, wherein the worm screw is kinematically connected in a rotationally fixed manner to a shaft of the electric motor, the helical toothed wheel is coupled to the worm screw and is kinematically connected in a rotationally fixed manner to an output shaft of the reduction gear box , wherein the crown wheel-pinion transmission system comprises a toothed pinion and a toothed crown wheel that are kinematically connected to each other by means of a roller chain , wherein the toothed pinion is kinematically connected in a rotationally fixed manner to the output shaft of the reduction gear box , and the toothed crown wheel is kinematically connected in a rotationally fixed manner to an output shaft of the moving device , characterized in that the reduction gear box has a reduction ratio R', defined as the ratio between the rotational speed ω1 of the motor shaft and the rotational speed ω2 of the output shaft of the reduction gear box , between 10:1 and 20:1 and is reversible, in that the crown wheel-pinion transmission system has a reduction ratio R", defined as the ratio between the rotational speed ω2 of the output shaft of the reduction gear box and the rotational speed ω3 of the output shaft of the moving device , between 4:1 and 6:1, and in that the chain of the crown wheel-pinion transmission system has a pitch between 6 mm and 8 mm and the toothed pinion has a number of teeth (z2) equal to 8. <EOS>