Earth boring equipment for core recovery

Claim 1

IN AN EARTH BORING TOOL ADAPTED FOR CORE RECOVERY, INCLUDING A HOLLOW MAIN BIT, A SECTIONAL TUBULAR DRILL STRING OF PIPE SECTIONS HAVING THE SAME EXTERNAL SIZE AND THE SAME INTERNAL SIZE CONNECTED END TO END TO FORM A SMOOTH UNOBSTRUCTED INNER SURFACE AND AT ONE UNCONNECTED END TO A HOLLOW MAIN BIT, A PILOT BIT OF A SIZE TO BE MOVABLE INTO SAID HOLLOW MAIN BIT THROUGH SAID TUBULAR DRILL STRING AND ADAPTED TO BE INDEPENDENTLY MANIPULATED BY AN AUXILIARY DRILL STRING EXTENDING THROUGH SAID MAIN DRILL STRING AND CONNECTED TO SAID PILOT BIT, THE IMPROVEMENT IN SAID EARTH BORING TOOL OF MEANS FOR SEPARATELY CONNECTING SAID PIPE SECTIONS END TO END AND TO SAID HOLLOW MAIN BIT COMPRISING, (A) A COLLAR SECURED TO THE OUTSIDE OF A PIPE SECTION SPACED FROM ONE END THEREOF TO FORM THEREWITH AN EXTERNALLY STEPPED TUBULAR END, (B) A COLLAR SECURED TO THE OUTSIDE OF A PIPE SECTION TO OVERHANG ONE END THEREOF TO FORM THEREWITH AN INTERNALLY STEPPED TUBULAR END, (C) MEANS FORMING CIRCUMFERENTIALLY SPACED JAWS ON THE RADIAL OUTER FACE OF EACH OF SAID COLLARS ARRANGED TO INTERLOCK WHEN SAID EXTERNALLY STEPPED TUBULAR END IS TELESCOPED WITH SAID INTERNALLY STEPPED TUBULAR END SO AS TO LOCK SAID PIPES AGAINST RELATIVE ROTATION AXIALLY THEREOF, (D) APERTURES FORMED IN ONE OF SAID COLLARS AND IN ONE OF SAID PIPE ENDS LOCATED TO REGISTER WHEN SAID JAWS ARE INTERLOCKED, (E) AND PIN MEANS REMOVABLY SECURED IN SAID APERTURES AND PROJECTING FROM THE OUTSIDE OF SAID DRILL STRING INTO BOTH APERTURES TO THE INSIDE SURFACE OF THE PIPE SECTION ONLY TO PROVIDE FOR UNOBSTRUCTED PASSAGE OF SAID PILOT BIT.