Rock drilling tool

Claim 1

IN A ROCK DRILLING TOOL, A BIT COMPRISING A BODY HAVING A PLURALITY OF DOWNWARDLY TAPERING RIBS PROJECTING RADIALLY OUTWARDLY FROM THE PERIPHERY THEREOF, SAID RIBS HAVING A PLURALITY OF INCLINED STEPPED FLAT SURFACES FORMING SEATS THEREON, SAID RIBS PROVIDED WITH A PLURALITY OF TAPERED CONICAL BORES OPEN AT EACH END AND OBLIQUELY DISPOSED RELATIVE TO THE LONGITUDINAL AXIS OF SAID BIT, ONE END OF EACH OF SAID BORES COMMUNICATING WITH A RELATED SEAT, SAID BODY ALSO HAVING AN INTERNALLY THREADED OPENING AT ITS INNER END AND A CENTRALLY DISPOSED SEAT AT ITS OUTER END AND DISPOSED TRANSVERSELY THEREOF, A CUTTER OF GENERALLY TRAPEZOIDAL SHAPE REMOVABLY SECURED IN SAID SEAT, A PLURALITY OF REMOVABLE AND INTERCHANGEABLE CUTTERS EACH HAVING A HEAD AND A TAPERED CONICAL SHANK DEPENDING THEREFROM, THE SHANK OF SAID CUTTER FITTED IN A RELATED BORE AND THE CUTTER HEAD RESTING ON A RELATED SEAT, AT LEAST ONE EDGE OF SAID HEAD ABUTTING AN ADJACENT EDGE OF SAID SEAT TO RESIST ROTATION DURING THE DRILLING OPERATION, AND A PLURALITY OF AIR DUCTS COMMUNICATING WITH THE INTERNALLY THREADED OPENING IN SAID BODY AND THE OUTER WALL OF SAID BODY IN AN AREA BETWEEN SAID RIBS.