Nut and sleeve fastener

1. A fastener, comprising:

a nut having an anterior portion, a posterior portion and a threaded bore with a center axis extending from said anterior portion to said posterior portion, the outer surface of said posterior portion having an annular flat camming block surface perpendicular to the center axis and a frustoconical camming surface concentric with said center axis, the camming surface having a radius that decreases along the direction of the center axis away from the anterior portion toward the posterior portion and the camming block having an inner radius greater than the maximum radius of the camming surface and being adjacent thereto; and

a cylindrical sleeve having a first end having an annular flat camming block surface perpendicular to the center axis and an internal frustoconical camming surface that engages said nut camming surface concentrically with said center axis and a second end having a thrusting surface, said sleeve being axially longer than said nut camming surface, the camming block having an inner radius greater than the maximum radius of the camming surface and being adjacent thereto, wherein tightening said fastener on an externally threaded member applies a force to said thrusting surface parallel to said center axis resulting in said nut camming surface and said sleeve camming surface cooperating to compress a portion of said threaded bore toward said threaded member, the compression being limited by engagement of said camming block surfaces.

2. A fastener according to claim 1 , wherein said posterior portion of said nut includes an annular flared out portion and the interior of the sleeve includes an annular lip, the flared portion and the lip cooperating to retain the nut and the sleeve together while permitting independent rotation about the central axis.

3. A fastener according to claim 1 , wherein said sleeve second end includes a crush portion that is crushable to provide a specific thrust load.