Russell, Burdsall & Ward Corporation

Other

John C McMurray

Arthur G Kudelko

A tri-lobular, all metal, prevailing torque nut is disclosed providing a cone having three locking sections, each of which extends around the threaded opening for about one-third of the surface of its thread. Each locking section provides a minimum radial distance at its center and extends with gradually increasing radial distance to the ends thereof. When the nut is threaded onto a mating threaded fastener, portions of each locking section are radially displaced from their unstressed condition to the circular shape of the mating fastener, producing frictional engagement between the nut and the fastener to resist unintentional loosening. Each locking section is arranged so that it provides a maximum resistance to deflection at its center and decreasing resistance to deflection at locations progressively spaced from the center so that excessive pressures are not developed which would tend to produce excessive wear or permanent deformation. Consequently, the locking torque or friction is maintained at satisfactory levels, even when the nut is assembled and disassembled with a mating threaded fastener a number of times. The nut is produced by forming a nut blank with a cone having three lobes symmetrically positioned around the cone which are deformed radially inward during staking to produce the locking sections along the threaded passage adjacent to the cone end of the nut.

Prevailing torque lock nut and method of forming same

A self locking threaded fastener is disclosed wherein the self locking system includes a plurality of bearing surfaces contained within a bearing plane and positioned in an annulus around the thread means. Extending inwardly from each bearing surface is a ramp surface which is inclined inwardly and back from the bearing plane. An axially extending shoulder joins one edge of each ramp surface. When the fastener is tightened against a mating part to clamp such part, the engagement causes sufficient pressure to displace material of the mating part by cold flow or other type of displacement into the recesses between the ramp surfaces and shoulders. Continued tightening rotation does not encounter excessive torque since the ramp surfaces provide a camming action but loosening rotation is resisted by the interference between the displaced material and the shoulders. As displacement occurs, additional portions of the ramp surface engages displaced material to increase the effective bearing area and locking interference and provide a self limiting action with respect to the extent the fastener embeds in the mating surface.

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Painesville, OH, United States of America

John C McMurray