The elevator door machine is a body that is responsible for opening and closing the car door. When it is closed by the elevator, the door signal is controlled by the built-in control system, and the torque generated by the motor is transformed into a specific direction Force, close or open the door. When the closing force is greater than 150N, the door automatically stops closing, and reverse open the door, play a certain degree of closing the role of protection. Door machine technology through the mechanical door machine, frequency door machine and permanent magnet synchronous door machine development. Among them, supporting timing belt and synchronous pulley is particularly important, plays a role in supporting.