How does the locknut prevent the nut from loosening?

A locknut is a kind of screw that has undergone an anti-loosening treatment, called an anti-loosening screw, which is suitable for fixing moving parts. So how does the locknut prevent the nut from loosening?
1. Prevent loosening by friction: This is a widely used method to prevent loosening. In this way, a positive pressure that does not change due to external forces is generated between the lock nut pair, friction is generated, and the relative rotation of the lock nut pair is prevented. power. This positive pressure can be obtained by pushing a pair of locknuts axially or simultaneously. Elastic washers, double nuts, self-locking nuts, plug-in locknuts, etc.
2. Riveting, punching, anti-loosening: After tightening, using punching, welding and bonding methods, the lock nut pair loses the performance of the movement pair, and the connection becomes an immovable connection. The disadvantage of this method is that the bolt can only be used once, it is difficult to disassemble, and it must be destroyed before disassembling a pair of bolts.
3. Prevent mechanical loosening: limit the relative rotation of the nut. Use open gear pins, serial wires, stop washers, etc. Since there is no pre-tightening force on the lock nut plug, the lock nut plug only works when the lock nut is loosened to the stop position, so it will not actually loosen and prevent it from falling.
4. Locking structure: adopts a lock nut replica structure, that is, a locking system that locks the nut downwards.