Preloaded locknut

Claim 1

A fastener assembly comprising an internally threaded nut having a thread of substantially uniform pitch with a wedge ramp at the root thereof diverging with respect to its central axis in a direction toward one end thereof, said nut having a truncated conical external portion divergent toward and located at the other end thereof, an externally threaded element having a standard thread sized so as to be receivable in said internally threaded element, the thread of said externally threaded element having a crest that exhibits an interference fit with the wedge ramp on the thread of said internally threaded element when said assembly is under load, and a preload washer permanently assembled with said nut and having a dished section normally spaced from the other end of said nut and a radially outer periphery engaged at all times with the other end of said nut, said washer having a conical flange at the outer periphery thereof extending axially and radially inwardly generally parallel to the conical portion of said nut and engageable therewith to maintain said nut and washer in the assembled condition, deflection of the dished section of said washer maintaining a bias on said nut relative to said externally threaded element in a direction toward said one end thereof whereby the crest of the threads on said element are maintained in engagement with the wedge ramp on said internal thread, the flanged portion of said washer having a plurality of longitudinally extending slots therein, the opposed side walls of said slots being disposed in convergent relation when said assembly is unloaded and parallel relation when said assembly is fully loaded so as to give visual indication of said loaded condition.