Reusable prevailing torque nut

Claim 1

A prevailing torque female fastener element for use in combination with a male threaded element having a standard thread form with standard flank angles, said female element comprising a nut body having a threaded hole at least partly therethrough, the threaded hole being characterized by a thread form having a first depth along a first portion thereof and a second reduced thread depth along a second portion contiguous with the first portion, said second reduced depth being formed by a truncation of the thread flanks thereby to define a flat surface of truncation at the major diameter of said second portion, the nut body being constructed to exhibit greater radial compliance in the portion of reduced thread depth, the increased radial compliance being achieved by a reduced wall thickness in the nut body surrounding the portion of reduced thread depth, thus to permit radial and circumferential expansion of the nut body when engaged with a male fastener element or standard thread form, at least the trailing flank angle of the nut body being greater than the corresponding mating flank angle of a standard male thread form so as to provide longitudinal clearance therebetween when threadedly engaged.