Locknut

[2] Free-spinning locknuts exist which carry the advantage of not requiring extra torque until seated.

[3] There are various kinds of specialised lock nuts, including: Prevailing torque[7] differentiates a locknut from a free spinning nut based on a value of how much torque is required during installation before clamp loading.

For example, on a nylon-insert nut, it is the torque needed to overcome the resistance of the nylon dragging across the mating thread.

Tolerance ranges for torque are specified in some standards such as (ISO, DIN, IFI, ASME, SAE, AN-, MS-, NAS- NASM-).

Other methods include safety wire, lock washers, and thread-locking fluid.