Bounding mass drilling tool

Claim 1

AN IMPROVED DRILLING TOOL FOR USE IN THE ROTARY DRILLING OF BOREHOLES WHEREIN A DRILLING FLUID IS CIRCULATED THROUGH THE BORE OF THE TOOL WHICH COMPRISES AN UPPER TUBULAR MEMBER ATTACHABLE TO THE LOWER END OF A ROTARY DRILL PIPE STRING, AN OUTER CASE SLIDABLY ATTACHED TO SAID UPPER TUBULAR MEMBER AND CO-ROTATABLE THEREWITH AND CONTAINING A DOWNWARD FACING INTERNAL SHOULDER IN THE UPPER BORE THEREOF, A LOWER TUBULAR MEMBER SLIDABLE IN SAID OUTER CASE BELOW SAID UPPER TUBULAR MEMBER AND HAVING A PISTON FACE ON ITS UPPER END, A VALVE SEAT ON THE UPPER END OF SAID LOWER TUBULAR MEMBER, A TAPERED VALVE PLUG MOUNTED ON THE END OF A VALVE STEM THAT IS SLIDABLY ATTACHED TO A BRACKET THAT IS MOUNTED IN SAID OUTER CASE ABOVE SAID VALVE SEAT, SAID VALVE PLUG ADAPTED TO SEAT IN SAID VALVE SEAT WHEREBY THE BORE OF SAID DRILLING TOOL IS CLOSED DIRECTING FLUID ABOVE SAID VALVE SEAT ONTO SAID DOWNWARD FACING INTERNAL SHOULDER TO MOVE SAID OUTER CASE UPWARD TO UNSEAT SAID VALVE PLUG DIVERTING FLUID PRESSURE ON SAID PISTON FACE ON SAID LOWER TUBULAR MEMBER TO THRUST SAID LOWER TUBULAR MEMBER DOWNWARD, AN ANNULAR CUTTING ELEMENT CONNECTED TO THE LOWER END OF SAID SLEEVE, AND A CENTRAL CUTTING ELEMENT CONNECTED TO THE LOWER END OF SAID LOWER TUBULAR MEMBER WITHIN SAID ANNULAR CUTTING ELEMENT.