Mine roof bolt expanding shells

Claim 1

A MINE ROOF BOLT EXPANSION ASSEMBLY COMPRISING A SHELL COMPOSED OF TWO SEPARATE SEMI-CYLINDRICAL MALLEABLE IRON SECTIONS, EACH SECTION HAVING A SLOT EXTENDING CENTRALLY FROM THE UPPER END TO A POINT SHORT OF THE LOWER END TO PROVIDE A PAIR OF SEGMENTS AND INTEGRAL MEANS CONNECTING THE SEGMENTS OF EACH SECTION AT THE LOWER END, EACH SEGMENT HAVING EXTERNAL GRIPPING TEETH AND UPWARDLY AND OUTWARDLY FLARING INSIDE CAMMING SURFACES, SAID CAMMING SURFACES BEING STRAIGHT CROSSWISE OF THE SEGMENTS, AND CONVEX LENGTHWISE SUBSTANTIALLY THE ENTIRE LENGTH OF THE SEGMENTS, A U-SHAPED BRIDGING RESILIENT STRAP HAVING A DEPENDING SUBSTANTIALLY PARALLEL SIDE PORTIONS TERMINATING WITH DOVETAIL END PORTIONS AFFIXED IN COMPLEMENTAL DOVETAIL RECESSES IN THE OUTSIDE UPPER END OF ONE SEGMENT OF EACH OF SAID SECTIONS, THE SIDE WALLS OF SAID RECESSES BEING SWAGED OVER AND RIGIDLY ENGAGING THE DOVETAIL END PORTIONS, AND A WEDGE MEMBER AXIALLY DISPOSED IN THE UPPER ENDS OF SAID SHELL SECTION AND HAVING AN AXIALLY THREADED BORE, SAID WEDGE MEMBER HAVING FOUR WEDGE FACES DISPOSED AT ANGLES OF 90 DEGREES FROM ONE ANOTHER AND EACH FACE BEING STRAIGHT TRANSVERSELY AND CONCAVE LENGTHWISE THEREOF AND COMPLEMENTAL TO SAID CAMMING SURFACES RESPECTIVELY AT THEIR UPPER ENDS, SAID WEDGE MEMBER HAVING OPPOSED SIDE GROOVES LOOSELY EMBRACING THE SIDE PORTIONS OF SAID STRAP AND OPPOSED WINGS DISPOSED IN A PLANE 45 DEGREES FROM THE PLANE OF SAID GROOVES AND ADAPTED TO SLIDE IN THE SLOTS BETWEEN THE SEGMENTS OF EACH SECTION.