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、污染物會(huì)妨礙得到準(zhǔn)確的扭矩值。如果零件和螺孔有污染物，將不可能有正確的扭矩值。

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、摩擦是普遍存在的現(xiàn)象，但也有好壞兩方面的作用。好的方面是使得零件保持結(jié)合在一起；壞的方面是，在扭緊時(shí)，它可能帶來錯(cuò)誤結(jié)果。一個(gè)技工用手?jǐn)Q緊聯(lián)接的力只有百分之10-20用于拉緊方面，而在很多情況下，有百分之40-50的扭矩是用來克服螺栓頭和零件之間的摩擦的，沿螺栓和螺孔的配偶螺紋表面還產(chǎn)生附加的摩擦。所以在擰緊螺栓時(shí)，應(yīng)把所有這些摩擦因素以及其它一些因素都考慮進(jìn)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、在擰緊螺紋上有損傷或障礙的螺母或螺栓時(shí)，要注意通過損傷部位需要附加的扭矩有多大，將此附加扭矩加到的扭矩值上。

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.