In some important occasions we will take some prevention measures, to ensure the reliability of the nut lock. Among them using the lock nut is a locking measure among them. Working principle of the nut is using self-locking of friction between the nut and bolt. But in the dynamic load will reduce the reliability of the self-locking.
There are three kinds of lock nut:
The first is to use the same two nut screw with a bolt, attach a tightening torque between two nut, bolt connection is reliable.
The second is a dedicated locknut, need and a locking washers are used together. Dedicated locknut is not hexagonal nut, but a kind of round nut, ball screw the nut on the circumference of a circle having 3 ~ 8 gap (depending on the size of nut and manufacturers products vary), these a few gap is the focus of tightening tools, and locking washers bayonet card into place.
The third one is in the cylindrical surface to the inner circle of nut thread runs through the thread hole is drilled surface (generally is 2 ~ 3, the outer circle are angled uniform), used to screw into the small diameter countersunk head screws, the purpose is to put a thread under direction of the centripetal force, prevent loosen lock nut. The lock nut on the downside, difficult to remove and repeated loading and unloading.