1. Pull the wrench gently and evenly. Do not use short and impulsive force to pull, because the jerk will produce an impulse. At the moment of stopping the force, the screw or bolt may have been over twisted.

2、污染物会妨碍得到准确的扭矩值。如果零件和螺孔有污染物，将不可能有正确的扭矩值。

2. Contamination will prevent accurate torque values from being obtained. If the parts and screw holes are contaminated, it is impossible to have the correct torque value.

3、摩擦是普遍存在的现象，但也有好坏两方面的作用。好的方面是使得零件保持结合在一起；坏的方面是，在扭紧时，它可能带来错误结果。一个技工用手拧紧联接的力只有百分之10-20用于拉紧方面，而在很多情况下，有百分之40-50的扭矩是用来克服螺栓头和零件之间的摩擦的，沿螺栓和螺孔的配偶螺纹表面还产生附加的摩擦。所以在拧紧螺栓时，应把所有这些摩擦因素以及其它一些因素都考虑进去。

3. Friction is a common phenomenon, but it also has good and bad effects. The good thing is to keep the parts together; The bad side is that when tightening, it can lead to wrong results. Only 10-20% of the force of a mechanic's hand tightening connection is used for tensioning, while in many cases, 40-50% of the torque is used to overcome the friction between the bolt head and parts, and additional friction is generated along the mating thread surface of the bolt and screw hole. Therefore, when tightening bolts, all these friction factors and other factors should be taken into account.

4、在拧紧螺纹上有损伤或障碍的螺母或螺栓时，要注意通过损伤部位需要附加的扭矩有多大，将此附加扭矩加到推荐的扭矩值上。

4. When tightening the nut or bolt with damage or obstacle on the thread, pay attention to the amount of additional torque required to pass through the damaged part, and add this additional torque to the recommended torque value.