Other names: root mother, anti-loosening nut, nazi.
Purpose: To lock the outer joint of the harness or other pipe fittings.
The working principle of the nut is self-locking by the friction between the nut and the bolt. However, the reliability of this self-locking under dynamic load will be reduced. In some important occasions, we will take some anti-loosening measures to ensure the reliability of the lock nut. The use of a lock nut is one of the anti-loosening measures.
There are also three types of lock nuts:
The first is to use two identical nuts to screw on the same bolt, and add a tightening torque between the two nuts to make the bolt connection reliable.
The second type is a special lock nut, which needs to be used together with a lock washer. The special lock nut is not a hexagonal nut, but a middle round nut. There are 3, 4, 6 or 8 gaps on the circumference of the nut (depending on the size of the nut and the product series of the manufacturer). Several notches are not only the focus of the tightening tool, but also the entry point of the locking washer.
The third type is to drill through threaded holes from the outer surface of the nut to the inner threaded surface (usually two, distributed at 90 on the outer surface) to screw in small-diameter countersunk screws. It is to apply a centripetal force to the thread to prevent the lock nut from loosening. A lock nut with better quality on the market is inlaid with a small piece of copper that is consistent with the thread of the lock nut on the inner surface of the nut to prevent the radial jack screw from directly contacting the locked thread and damaging the latter . This kind of lock nut has gradually begun to be applied in the occasion of the shaft end locking of rotating parts, such as the anti-loosening of the bearing at the mounting end of the ball screw.
The second anti-loose method is more reliable than the first, but the structure is relatively complicated. Compared with the first two, the third clock has the characteristics of better anti-loosening effect, simpler and more beautiful structure, and smaller axial size.
