Common misunderstandings in the use of standard parts:

01 Substitute coarser for finer

For important couplings on the machine, such as drive shafts, flyshafts, etc., the bolts mostly use fine thread. When parts are missing in the repair, someone replaces them with coarse-threaded bolts. Because of the larger inner diameter, smaller pitch and outer angle, the fine pitch bolt has the advantages of high strength, good self-locking performance, etc., and strong ability to withstand impact, vibration and exchange load; it is easy to loosen or fall off and break after being replaced by coarse-threaded bolts. , Causing a mechanical accident.

02 Pore does not match

The bolts (such as drive shaft bolts, flywheel bolts) on the machine that bear the lateral load and shearing force, their fit with the bolt holes are transitional fits, and the assembly should be strong and reliable, and can withstand lateral forces. Someone did not pay attention to the inspection during the assembly, and the bolt was still installed when there was a large gap between the bolt and the bolt hole. As a result, the bolt was loose or cut off.

03 Thick nut

Some people often mistakenly believe that thickening the nut can increase the number of working turns of the thread, thereby improving the reliability of the coupling. In fact, the thicker the nut, the more uneven the load distribution between the threads of each circle, and the easier it is to loosen the coupling.