In actual production, CNC machine tools do not need to have constant power throughout the entire speed range. Generally, constant power transmission is required in the middle and high speed sections, and constant torque transmission is required in the low speed section. In order to ensure that the spindle of a CNC machine tool has a large torque and a wide range of speed changes when it is running at a low speed, some CNC machines are equipped with a gear speed change based on an AC or DC motor stepless speed change, making it a segmented stepless speed change.