Bell and spigot tile and seal joint therefor

Claim 1

A TILE HAVING A SPIGOT AT ONE END AND A BELL AT THE OTHER END, THE BELL HAVING FORMED THEREON A TRUED ANNULAR INTERNAL SEALING SURFACE OF CIRCULAR CROSS SECTION, THE SPIGOT END HAVING FORMED THEREON A TRUED ANNULAR EXTERNAL SEALING SURFACE, SAID SURFACES BEING CIRCULAR IN CROSS SECTION AND SO POSITIONED ENDWISE OF THE TILE AND OF SUCH A DIAMETER THAT, SHOULD THE TILE BE JOINED WITH TWO DUPLICATE TILES, THE SEALING SURFACES OF THE SPIGOT AND BELL, RESPECTIVELY, WOULD BE ALIGNED RADIALLY WITH, AND IN RADIALLY SPACED RELATION TO, THE COOPERABLE SEALING SURFACES OF THE BELL OF ONE DUPLICATE TILE AND OF THE SPIGOT OF THE OTHER DUPLICATE TILE, FOR ACCOMMODATING RESILIENT SEALING GASKETS IN COMPRESSED CONDITION RESPECTIVELY, BETWEEN THE ALIGNED SEALING SURFACES, SAID GASKETS EACH BEING A PREFORMED ANNULUS OF RESILIENT ELASTOMERIC MATERIAL NORMALLY OF SMALLER INTERNAL DIAMETER THAN THE SPIGOT SEALING SURFACE AND IN TIGHT STRETCHED FITTING ENGAGEMENT WITH THE SEALING SURFACE OF ITS ASSOCIATED SPIGOT, EACH ANNULUS HAVING A TAPERED PORTION WITH AN EXTERIOR PERIPHERAL SURFACE WHICH IS SMOOTH AND, INSTALLED POSITION OF THE ANNULUS, IS CIRCULAR IN CROSS SECTION AND OF PROGRESSIVELY INCREASING DIAMETER IN A DIRECTION AWAY FROM THE SPIGOT END OF THE ASSOCIATED TILE, AND WHICH IS DISPOSED WITH ITS SMALLER DIAMETER AT THE SPIGOT END OF THE ASSOCIATED TILE, SAID ANNULUS HAVING A SEALING PORTION WITH A CYLINDRICAL SEALING SURFACE OF SUBSTANTIAL EXTENT ENDWISE OF THE TILE, ADJACENT THE LARGER END OF THE TAPERED PORTION, AND SAID BELL AND SPIGOT EACH HAVING A LOAD BEARING SURFACE PORTION ADJACENT THE END OF ITS SEALING SURFACE, SAID LOAD BEARING SURFACE PORTIONS OF AN INTERFITTING BELL AND SPIGOT BEING AT THE END OF THE CYLINDRICAL SEALING SURFACE OF THE ANNULUS OPPOSITE FROM SAID TAPERED PORTION, AND OF RADIAL EXTENT SUCH THAT, IN INTERFITTING DUPLICATE TILES, THEY WILL BE RADIALLY SPACED A LIMITED DISTANCE SO AS TO ENGAGE AND LIMIT THE TRANSVERSE MOVEMENT OF THE INTERFITTING BELL AND SPIGOT TO LESS THAN THAT WHICH WOULD BE PERMITTED BY FULL COMPRESSION OF THE SEALING PORTION OF THE ANNULUS AT ONE SIDE OF ITS AXIS AND TO LESS THAN THAT WHICH WOULD PERMIT THE ANNULUS TO REACH ITS SUBSTANTIALLY FULLY UNCOMPRESSED CONDITION AT THE DIAMETRICALLY OPPOSITE SIDE OF THE AXIS, SAID SPIGOT HAVING AN ANNULAR RADIALLY EXTENDING POSITIONING SHOULDER ADJACENT THE INNER END OF ITS SEALING SURFACE AND FACING THE ADJACENT END OF THE TILE, AND THE ANNULUS HAVING AN ANNULAR RADIALLY EXTENDING SHOULDER AT ITS INNER END JUXTAPOSED THEREAGAINST.