Tamper-proof two-way locking nut

Claim 1

A locknut comprising: an annular conical nut body having a relatively thick base and a relatively thin tip; female threads within said body, extending substantially from end to end thereof; a generally radial wrenching shoulder provided by one side of a slot extending generally parallel to the nut axis in the side of the nut; the alternate side of said slot being defined by a chamfer; said slot having a chordal bottom parallel to the nut axis; said bottom and chamfer subtending a dihedral angle, to prevent rotation of the nut by a spanner wrench in a back-off direction; said nut body having an external circumferential groove encircling it substantially midway between its ends and intersecting said slot; the bottom of said groove being at a distance no less than the radial distance of the bottom of said slot frOm the nut axis; and a thread lock comprising a radially inwardly deformed portion of a web of the nut body wall defining the bottom of said slot in the intersection of said groove and slot; the remainder of the wall of said nut body and the threads of both ends thereof beyond said circumferential groove, retaining a true circular cross-section; said nut body having respective end portions of substantially equal length extending axially from both sides of said circumferential grooves; the said locations of said circumferential groove and thread lock and the true circular cross sections adapting said nut for easily threading it onto a complementary threaded member either base-first or tip-first.