Drilling shaft coupling having pin securing means

Claim 1

A SECTIONAL, HIGH TORQUE, ROTATABLE DRILLING SHAFT, COMPRISING SEPARABLE, FIRST AND SECOND TUBULAR DRILLING SHAFT ELEMENTS, EACH FORMED TO INCLUDE A CENTRAL DRILLING FLUID PASSAGEWAY, AND A SLIPJOINT CONNECTION BETWEEN SAID ELEMENTS SUBJECTED TO A HIGH DEGREE OF TORQUE DURING DRILLING, SAID JOINT COMPRISING: (A) A TUBULAR BOX AT AN END OF THE FIRST DRILLING ELEMENT, SAID BOX INCLUDING SIDE WALL MEANS FORMING AN AXIALLY EXTENDING BOX OPENING, CONSTITUTING AN END PORTION OF THE DRILLING FLUID PASSAGEWAY IN SAID FIRST DRILLING SHAFT ELEMENT, WITH AT LEAST ONE PAIR OF OPPOSED, INWARDLY TAPERING OPENINGS EXTENDING LATERALLY THROUGH SAID SIDE WALL MEANS; (B) A TUBULAR PIN AT AN END OF THE SECOND DRILLING SHAFT ELEMENT, SNUGLY INSERTABLE INTO SAID BOX OPENING, SAID PIN INCLUDING SIDE WALL MEANS FOR AT LEAST ABOUT THE SAME THICKNESS AS THE WALL MEANS FORMING SAID BOX, AND FORMING A PASSAGEWAY IN THE PIN THAT CONSTITUTES A REDUCED DIAMETER END PORTION OF THE DRILLING FLUID PASSAGEWAY IN SAID SECOND DRILLING SHAFT ELEMENT, WITH AT LEAST ONE PAIR OF OPPOSED, INWARDLY TAPERING OPENINGS EXTENDING LATERALLY THROUGH SAID SIDE WALL MEANS AND BEING REGISTERABLE WITH THE SAID INWARDLY TAPERING OPENINGS OF SAID BOX, WHEN THE PIN IS IN THE BOX OPENING, TO FORM A PAIR OF OPPOSED, INWARDLY TAPERING BORES; AND (C) A COUPLING ASSEMBLY COMPRISING A PAIR OF PLUG ELEMENTS INSERTABLE INTO SAID INWARDLY TAPERING BORES, AND EACH BEING OF ONE-PIECE CONTINUOUS FORM AND INCLUDING TAPERED SIDE SURFACES OF LIKE TAPER AS ITS BORE, AND EACH SIZED TO SNUGLY FIT WITHIN ONE OF SAID BORES, AND BOLT MEANS DETACHABLY CONNECTABLE TO SAID PLUG ELEMENTS FOR PULLING THEM TOGETHER AND THEIR TAPERED SIDE SURFACES INTO TIGHT ENGAGEMENT WITH THE SIDE SURFACES OF SUCH BORES, WITH THE COMBINED LENGTH OF SAID BOLT MEANS AND SAID PAIR OF PLUG ELEMENTS WHEN IN THE ASSEMBLED POSITION BEING NOT MORE THAN ABOUT THE OUTER DIAMETER OF SAID TUBULER BOX.