Prevailing torque fastener assembly
OwnerGeorge S. Winginventor
Life of this patent
Estimating the term…
Abstract
A tri-lobular section of a bolt receives a mating tri-lobular bore of a washer to prevent the washer from rotating. Roll formed male threads on the tri-lobular section of the bolt receive a cooperating nut. The nut has a base shaped for wrench engagement, a thin walled barrel, a spring temper, and a threaded bore. The thread of the nut has two thread diameters: a large diameter thread in the base and a smaller diameter thread in the barrel continuing from the base thread; both thread sections have the same pitch. The barrel thread is substantially circular when relaxed. The barrel elastically flexes in response to the lobes of the nut as the lobes turn in the barrel, and when rotation stops, the barrel generally conforms to the tri-lobular shape of the bolt to form a thread lock, but the base does not.
Claims22
An improved fastener assembly of a male fastener with a threaded shank engaged with a female fastener with a threaded axial bore comprising:
- (a) a tri-lobular shape of the shank having three equiangularly spaced lobes with a side between each lobe, the tri-lobular shape having the same diametric dimension regardless of where taken around 360.degree.;
- and
- (b) the female fastener having a base and a barrel, the threaded bore extending through both the base and the barrel as a continuous thread with the thread in the barrel having a smaller pitch diameter than the thread in the base, a radius to the tip of a lobe being greater than a radius to the root of the thread in the barrel, the female thread in the barrel when unstressed being substantially circular in cross-sections taken perpendicular to the axis of the female fastener but being elastically deformed into substantial conformity with the tri-lobular shape by the thread engagement between the barrel and the shank to form a prevailing torque thread lock, the female thread in the base being in threaded engagement with the shank and in such engagement being circular in cross-sections taken perpendicular to the axis of the nut.
In a spindle assembly having an axle for mounting a wheel, a male threaded shank, a barrier washer, and an adjusting nut, an improvement comprising:
- (a) the shank having a tri-lobular shape with three lobes and a side between each lobe, the shank having the same dimension between any two diametric points on its perimeter, the shank being circumferentially continuous without any axial slots, the thread on the shank being roll formed;
- (b) the nut having a base and a barrel with a threaded axial bore through both, the thread having a smaller pitch diameter in the barrel than in the base, a radius to the tip of a lobe being greater than a radius to the root of the thread in the barrel, the thread in the barrel when unstressed being substantially circular in cross-sections taken perpendicular to the axis of the nut, but being elastically deformed into substantial conformity with the tri-lobular shape by the thread engagement between the barrel and the shank to form a prevailing torque thread lock, the thread in the base being in engagement with the thread in the shank and being substantially circular in cross-sections taken perpendicular to the axis of the bore;
- and
- (c) the barrier washer having a tri-lobular in perimeter axial bore mating with and received by the shank with the washer being captured by the shank against relative rotation.
Dependencies are inferred from the claim text.