Expansion shell

Claim 1

AN EXPANSION SHELL ASSEMBLY FOR MINE ROOF SUPPORT AND THE LIKE CONSISTING OF AN EXPANSION SHELL AND WEDGE, SAID EXPANSION SHELL COMPRISING A ONE PIECE MALLEABLE IRON CASTING IN THE FORM OF A GENERALLY HOLLOW CYLINDRICAL MEMBER, SAID MEMBER HAVING A PLURALITY OF SLITS EXTENDING LENGTHWISE THEREOF SUBDIVIDING THE SHELL INTO FOUR SUBSTANTIALLY EQUAL ARCUATE SEGMENTS, SAID SEGMENTS EACH HAVING A SERIES OF UNIFORMLY LENGTHWISE SPACED ARCUATE GRIPPING TEETH ON THEIR EXTERNAL FACES OVER A SUBSTANTIAL PORTION OF THE LOWER HALF OF THE LENGTH OF THE SHELL, AND HAVING TRANSVERSELY CONCAVE AND LONGITUDINALLY CONVEX CAMMING SURFACES BEHIND SAID TEETH ON THEIR INSIDE FACES, SAID CAMMING SURFACES EXTENDING UPWARDLY AND FLARING OUTWARDLY, SAID SHELL HAVING A PAIR OF SPACED PARALLEL UPWARDLY EXTENDING ARMS INTEGRAL WITH AND EXTENDING UPWARDLY FROM AT LEAST TWO OF SAID SEGMENTS THAT ARE OPPOSITELY DISPOSED, AND SAID ARMS BEING IN ALIGNMENT WITH TWO OF SAID SLITS THAT ARE OPPOSITELY DISPOSED, AND INTEGRAL DEFORMABLE TAB MEANS EXTENDING INWARDLY TOWARD THE AXIS OF THE SHELL AT THE UPPER END THEREOF IN THE PLANE OF SAID ARMS, SAID EXPANDING WEDGE HAVING AN UPPER CYLINDRICAL PORTION HAVING LENGTHWISE EXTENDING GROOVES ON ITS EXTERIOR EMBRACING SAID ARMS TO CONFINE THE WEDGE WITHIN THE SHELL AND RESIST RELATIVE ROTATION THEREBETWEEN, AND A TAPERED WEDGE PORTION EXTENDING UPWARDLY AND TAPERING OUTWARDLY FROM ITS LOWER END AND COMPLEMENTAL TO A PORTION OF SAID CAMMING SURFACES OF SAID SEGMENTS, SAID WEDGE MEMBER HAVING AN AXIAL THREADED BORE TO RECEIVE THE THREADED END OF AN EXPANSION BOLT, AND SAID TAB MEANS EXTENDING AT LEAST PARTIALLY ACROSS THE THREADED BORE, AND ADAPTED TO ENGAGE THE END OF AN EXPANSION BOLT WHEN THREADED THROUGH THE WEDGE BORE TO PROVIDE INITIAL DOWNWARD THRUST OF SAID WEDGE TO SPREAD SAID SEGMENTS.