When confirming the contents of the operation instructions for generator parts, it shall not only compare with relevant standards, but also combine the current situation of the enterprise. For example, if the machining allowance for the machining process of the mounting surface of the bearing seat on the rack is not combined with the accuracy of the enterprise equipment, it is only set according to the national standards, so that the product quality is difficult to be guaranteed. After knowing the root cause of the machining allowance setting, the supervisor can timely adjust the witness focus. So that the quality of the process can be fully controlled. As the water-cooled alternator greatly inhibits the temperature rise of stator, rotor and regulator, it can correspondingly increase the excitation current. The larger the excitation current is, the higher the output voltage is. Therefore, when the water-cooled alternator rotates at low speed, it will also have good charging performance. This low-speed charging performance is very important for the normal use of urban vehicles.