Prevailing torque locknut

Claim 2

A prevailing torque locknut comprising a polygonal body having base and top ends, a central threaded bore extending from the base end to the top end, at least six longitudinal side walls arranged about the threaded bore, and a locking zone in said bore longitudinally spaced at least from the base end sufficiently to provide a plurality of thread turns of normal configuration for free-running initial engagement with a threaded bolt, the locking zone being formed by a single transversely arcuate punched indentation in each of a plurality of alternate side walls of the body in an initially flat portion of said wall intermediate said base and top ends, the major portion of said indentation being an arcuate surface substantially concentric with the axis of said threaded bore, each indentation having a longitudinal length greater than the pitch of the thread and a transverse length less than the width of said side wall and being of a depth sufficient to displace at least two thread crests and at least one thread root radially inward of the original thread diameter in the area of the thread bore normal to the indentation, said displaced thread root and adjacent thread flanks having a substantially parabolic curvilinear configuration in longitudinal section, said displaced thread crests at each side of said displaced thrEad root being longitudinally displaced a distance greater than the original pitch of the thread, the thread crests and roots in the areas normal to the unindented intervening side walls being displaced radially outward of the original thread diameter.

Claim 3

The locknut claimed in claim 1, wherein each indentation has a longitudinal length of from one to three times the pitch of the thread, whereby at least two thread crests and at last one thread root therebetween are displaced radially inward of the original thread diameter in the area of the thread bore adjacent and normal to said indentation.

Claim 4

The locknut claimed in claim 2, wherein said thread crests and root in the area adjacent and normal to each indentation are displaced radially inward a distance substantially greater than the distance which said crests and roots in the area adjacent and normal to each unindented side wall are displaced radially outward.

Claim 5

The locknut claimed in claim 1, wherein each said arcuate portion merges smoothly at each end thereof with an upward, outwardly sloping surface.

Claim 6

The locknut claimed in claim 1, wherein the depth of indentation of at least one side wall differs from the depths of indentation of the others.

Claim 7

A prevailing torque hexagonal locknut comprising a polygonal body having base and top ends, a central threaded bore extending from the base end to the top end, six longitudinal side walls arranged about the threaded bore, and a locking zone in said bore longitudinally spaced at least from the base end a distance sufficient to provide a plurality of thread turns of normal configuration for free-running initial engagement with a threaded male member, the locking zone being formed by a single transversely arcuate punched indentation in each of three alternate side walls of said body in an initially flat portion of said wall intermediate said base and top ends, the major portion of said indentation being an arcuate surface substantially concentric with the axis of said threaded bore, each indentation having a longitudinal length from one to three times the pitch of the thread and a transverse length less than the width of said side wall and being of a depth sufficient to displace at least two thread crests and at least one thread root therebetween radially inward of the original thread diameter in the area of the thread bore normal to the indentation, said displaced thread root and adjacent thread flanks having a substantially parabolic curved configuration in longitudinal section, said displaced thread crests at each side of said displaced thread root being longitudinally displaced a distance greater than the original pitch of the thread, the thread crests and roots in the areas normal to the unindented intervening side walls being displaced radially outward of the original thread diameter.

Claim 8

A prevailing torque hexagonal locknut comprising a polygonal body having base and top ends, a central threaded bore extending from the base end to the top end, six longitudinal side walls arranged about the threaded bore, and a locking zone in said bore longitudinally spaced at least from the base end a distance sufficient to provide a plurality of thread turns of normal configuration for free-running initial engagement with a threaded male member, the locking zone being formed by a single transversely arcuate punched indentation in each of three alternate side walls of said body in an initially flat portion of said wall intermediate said base and top ends, the major portion of said indentation being an arcuate surface substantially concentric with the axis of said threaded bore, each indentation having a longitudinal length from one to three times the pitch of the thread and a transverse length less than the width of said side wall and being of a depth sufficient to displace at least two thread crests and at least one thread root therebetween radially inward of the original thread diameter in the area of the thread bore normal to the indentation, said displaced thread root and adjacent thread flanks having a substantially parabolic curved configuration in longitudinal section, said displaced thread crests at each side of said displaced thread root being longitudinally displaced a distance greater than the original pitch of the thread, the thread crests and roots in the areas normal to the unindented intervening side walls being displaced radially outward of the original thread diameter.