Abstract: A lock nut capable of improving a fastening force of a fastening nut and the lock nut is provided. The lock nut includes a body having a threaded throughhole and a groove formed at a circumferential edge thereof. A plurality of projections are formed in the groove and each includes an outer side face directed toward a center of the body from a border between a seat surface and the groove. An inner side face serves as an extension of an inner face of the threaded throughhole. A depth of the groove is such that if the projections are crushed when the lock nut is fastened against a bolt, they do not enter a space between a seat surface on the side of the body of the fastening nut and the seat surface of the lock nut body.

Abstract: A retaining member (26) is constructed undersized from a memory metal for permitting a member (26) disposed in an element retaining position to recover and grippingly engage a stud (12) on which the member (26) is arranged. The retaining member (26) can be used alone, or in combination with a load-carrying nut (16) for greater strength. Providing a convex face (46) on the retaining member (26), and a concave surface (40) on the load-carrying nut (16), permits the total height of the arrangement to be limited to only slightly more than the height of the load-carrying nut alone in order to meet existing space limitations.