Patent ID: 7192232

Claim:
A self-locking fastening device for engaging a screw or nut for fastening at least a first member to another member, wherein the fastening device comprises a washer having a central bore hole and two surfaces, one of said surfaces being a concave side and the other of said surfaces being a convex side, having rib profiles configured to prevent self-actuated unscrewing, said washer being configured in such a resilient manner that said washer is compressible counter to its resilience thereof by being cambered in an axial direction, wherein the rib profile on the convex side is positioned in an inner area of the washer, proximate the bore hole, and the rib profile on the concave side is positioned in an exterior area of the washer, proximate to an exterior edge of the washer, and that the rib profiles of each of the convex and concave sides each extend over at least half and at most tow thirds of the width of the washer, said width being an area between the bore hole and the exterior edge of the washer.