In addition to the nut that never loosens, there is no other way to prevent the bolt from loosening. Relaxation measures commonly used in production are as follows:

1, double nut double nut lock, also known as the top nut lock, when the two top nuts are tightened, there is always interaction pressure between the two top nuts, and any one of the two nuts needs to be turned to overcome the friction between the screw threads. Even if the external load changes, the pressure between the top nuts is always present, so it can play a relaxing role.

2. Lock nut

The self-locking nut generally relies on friction, and its principle is to press into the preset hole of the sheet metal through the embossed teeth, and the aperture of the general square preset hole is slightly less than that of the riveted nut. The nut is connected to the locking mechanism. When the nut is tightened, the locking mechanism locks the bolt thread.

3, thread locking adhesive

Thread locking adhesive is a adhesive composed of (methyl) acrylate, initiator, promoter, stabilizer (inhibitor), dye and filler, etc., which are combined together in a certain proportion.

4. After the cotter pin nut is tightened, insert the cotter pin into the nut slot and the bolt tail hole, and open the cotter pin tail to prevent the relative rotation of the nut and bolt.

5, high-strength bolt connection generally does not need to apply additional anti-loosening measures, because high-strength bolts generally require the application of a relatively large pre-tightening force, such a large pre-tightening force produces a strong pressure between the nut and the connected part, this pressure will produce friction torque to prevent the nut from rotating, so the nut will not loose.