Drive member for a door or main door, comprising at least drive means able to generate a motion having a determinate torque and a determinate speed, and reducing means able to be connected on one side to the output of said drive means and, on the other side, to said door, in order to vary in a desired manner the values of torque and speed of the motion generated by said drive means, so as to determine the correct movement of said door, wherein said drive means comprise an electric motor having a drive shaft able to transmit said motion, and a first reduction kinematism directly connected mechanically to said drive shaft and able to determine a first variation in the ratios of torque and speed of the motion, in order to transmit them to an associated first transmission shaft, wherein said reducing means comprise: - a second transmission shaft mechanically connected and coaxial to said first transmission shaft; - a second reduction kinematism mechanically connected to said second transmission shaft, and able to determine a second variation in the ratios of torque and speed of the motion; - a third reduction kinematism kinematically connected to said second reduction kinematism, and able to determine a third variation in the ratios of torque and speed of the motion; - a third transmission shaft mechanically connected to said third reduction kinematism; - a fourth reduction kinematism mechanically connected to said third transmission shaft, and able to determine a fourth variation in the ratios of torque and speed of the motion; and - a fourth transmission shaft, mechanically connected to said fourth reduction kinematism, and to which said door is able to be mechanically connected; wherein the fourth transmission shaft is located in an intermediate position between the second transmission shaft and the third transmission shaft; and the fourth transmission shaft is parallel to the third transmission shaft that is parallel to the second transmission shaft and to the first transmission shaft, wherein said second reduction kinematism comprises a grooved profile made directly on said second transmission shaft, and a coordinated toothed wheel engaging with said grooved profile and mounted idly on said fourth transmission shaft, and wherein said third reduction kinematism comprises at least a first toothed wheel coaxially and angularly constrained to said toothed wheel of the second reduction kinematism and mounted idly on said fourth transmission shaft, and a coordinated second toothed wheel engaging with the relative first toothed wheel and keyed onto said third transmission shaft, wherein said first reduction kinematism comprises at least a screw element keyed coaxially to said drive shaft, and a coordinated pulley engaging with said screw element and keyed coaxially onto said first transmission shaft, and wherein said drive shaft is disposed substantially orthogonally to said first transmission shaft whereby said electric motor is disposed substantially orthogonally to said second transmission shaft, third transmission shaft and fourth transmission shaft, and wherein said fourth reduction kinematism comprises a grooved profile made directly on said third transmission shaft, and a coordinated toothed wheel engaging with said grooved profile and keyed onto said fourth transmission shaft. - a second transmission shaft mechanically connected and coaxial to said first transmission shaft; - a second reduction kinematism mechanically connected to said second transmission shaft, and able to determine a second variation in the ratios of torque and speed of the motion; - a third reduction kinematism kinematically connected to said second reduction kinematism, and able to determine a third variation in the ratios of torque and speed of the motion; - a third transmission shaft mechanically connected to said third reduction kinematism; - a fourth reduction kinematism mechanically connected to said third transmission shaft, and able to determine a fourth variation in the ratios of torque and speed of the motion; and - a fourth transmission shaft, mechanically connected to said fourth reduction kinematism, and to which said door is able to be mechanically connected;