Expansion shell assembly

Claim 1

A mine roof expansion shell assembly comprising, in combination: a. a one-piece ring having concentric interior and exterior surfaces of first and second diameters, respectively, and a planar lower surface; b. four expansion fingers formed integrally with said ring and extending substantially axially thereof from the surface opposite said lower surface in spaced relation to one another, defining therebetween four spaces of predetermined width at 90* intervals, each of said fingers being of substantially the same length and having a free end opposite the juncture with said ring; c. a wedge disposed at least partly within the space enclosed by the free ends of said fingers and having a central, threaded aperture coaxial with said ring, and four wedge faces, each in contact with a respective internal surface of one of said fingers and sloped with respect to the axis of said aperture and ring so that movement of said wedge toward said ring forces said fingers outwardly; and d. a substantially U-shaped strap extending over the end of said wedge farthest from said ring, and through two opposite ones of said four spaces, the width of said strap being less than said predetermined width, and passing through said ring to terminal end portions which are bent over to extend in closely adjacent, overlying relation to said lower surface and terminate at ends spaced by a distance not greater than said second diameter and biased toward outward movement; e. the space between the opposing portions of said strap extending through said ring being at least as great as the major diameter of said threaded aperture, and the length of said strap from said end portions to the end extending over said wedge being less than the combined length of said fingers and said wedge, whereby said strap serves to retain said wedge within the space enclosed by the free ends of said fingers.