3. High performance of the servo motor (hereinafter referred to as servo motor) : used for efficient and complexity of surface processing of CNC machine tool, servo system will often in the frequent starting and braking requirement in the process of motor output torque and the moment of inertia ratio is large, to generate large enough acceleration or braking torque. For servo motor at low speed are sufficiently large output torque and smooth operation, so that the mechanical part as far as possible to reduce the intermediate links in the connection.