The working principle of the electric torque wrench is that after the motor decelerates through the planetary gear mechanism, the power is transmitted to the impact head. The two convex heads of the impact head drive the pull shaft to rotate through the pull shaft claw, and the power output is completed by the pull shaft. After using for a period of time, the output power of the electric torque wrench began to drop. With the continuous use of the equipment, the output power continued to drop until it could not work.

其实，有用延长电扭矩动扳手的使用寿命，就一定要解决磨损问题。并且由于扳轴磨损比冲击头要更严重，所以，扳轴磨损的问题是关键。若此问题得以解决，冲击头磨损问题也就迎刃而解了。将整体式的扳轴改为拆分式的，扳轴的工作面可以拆卸，在使用一段时间后，可视其磨损情况进行更换。

In fact, to prolong the service life of the electric torque wrench, we must solve the problem of wear. And because the wear of the pull shaft is more serious than that of the impact head, the wear of the pull shaft is the key. If this problem can be solved, the problem of impact head wear will be solved. The working face of the pull shaft can be disassembled. After a period of use, it can be replaced according to its wear condition.

活动工作面可单独选用适合的材料，通过合理的加工工艺过程，达到较高的机械性能。因此选用高碳钢，进行先淬火后中温回火的热处理工艺。这样加工后的活动工作面既有较高的硬度又有一定的韧性，使其在经受冲击时不会发生断裂。且可以进行大批量的加工，一次加工即可满足长期更换的使用要求。

Suitable materials can be selected for the movable working face, and high mechanical properties can be achieved through reasonable processing technology. Therefore, high carbon steel is selected for the heat treatment process of quenching first and then tempering at medium temperature. In this way, the working face after processing has both high hardness and certain toughness, so that it will not fracture when subjected to impact. And it can be processed in large quantities, and one processing can meet the requirements of long-term replacement.