Patent ID: 7392676

Claim:
A key blank for a cylinder lock comprising: a bow, a blade longitudinally extending from said bow to a tip, and having a longitudinally extending upper edge having a front portion to be cut with coded bitting for mating with a tumbler stack of a cylinder lock and a spaced, longitudinally extending lower edge, and side faces which connect said edges; upper and lower projections extending outwardly on respective edges adjacent the bow, the upper projection rising about a vertical centerline from a reference elevation e 0 below the elevation e 1 of the front portion of the upper edge to a nose at an elevation e 3 above said elevation e 1 , and extending a length parallel to the upper edge that is greater than a width transverse to the edge; wherein said upper projection has a convexly contoured longitudinal cam surface facing the tip of the blade and a convexly contoured longitudinal cam surface facing the bow, which converge toward said nose.