Stab type pipe coupling with gasket back up ring

Claim 1

IN A PIPE JOINT, A PAIR OF MEETING PIPE ENDS TO BE JOINED EACH HAVING A PLAIN OUTER CYLINDRICAL SURFACE AND A FREE END, A COUPLING SLEEVE RECEIVING SAID PIPE ENDS AND HAVING AN INNER CONICAL SURFACE AT EACH END TERMINATING AT ITS OUTER END IN A PIPE RECEIVING APERTURE, THERE BEING AN INNER CYLINDRICAL SURFACE ADJACENT TO AND MERGING IN WITH THE LARGER END OF EACH OF SAID CONICAL SURFACES, THE OUTER SURFACE OF EACH PIPE END AND THE ADJACENT CONICAL AND CYLINDRICAL SURFACES OF SAID SLEEVE DEFINING A GASKET RECEIVING RECESS, A GASKET OF A FIRM ELASTOMER MATERIAL IN EACH OF SAID RECESSES, EACH OF SAID GASKETS HAVING AN INNER BORE ENGAGING THE RESPECTIVE PIPE END, AN OUTER TAPERED SURFACE ENGAGING THE CONICAL SURFACE OF THE SLEEVE, AND AN OUTER CYLINDRICAL SURFACE ENGAGING THE CYLINDRICAL SURFACE OF THE SLEEVE, THE COEFFICIENT OF FRICTION BETWEEN THE BORE OF THE GASKET AND THE OUTER SURFACE OF THE PIPE BEING AT LEAST TWO TIMES AS GREAT AS THE COEFFICIENT OF FRICTION BETWEEN THE ENGAGING TAPERED AND CONICAL SURFACES, AND A PAIR OF BACK UP RINGS WITHIN SAID SLEEVE THERE BEING ONE BACK UP RING BETWEEN THE FREE END OF EACH PIPE END AND THE GASKET THEREABOUT, SAID BACK UP RINGS HAVING PIPE ENGAGING MEANS AND GASKET ENGAGING MEANS TO PREVENT WALKING MOVEMENT OF SAID GASKETS TOWARD THE FREE ENDS OF SAID PIPE ENDS.