The mechanical spindle refers to the shaft on a machine tool that drives the workpiece or tool to rotate. Generally, the main shaft components are composed of the main shaft, bearings, and transmission parts (gears or pulleys). In machines, it is mainly used to support transmission parts such as gears and pulleys, and transmit motion and torque, such as the machine tool spindle; Some are used for clamping workpieces, such as mandrels.