Torsional drive coupling

Claim 1

A TORSIONAL DRIVE COUPLING FOR ROTARY DRILL PIPE STRINGS, COMPRISING CONCENTRIC TELESCOPICALLY DISPOSED TUBULARE OUTER AND INNER COUPLING ELEMENTS CONNECTIBLE RESPECTIVELY TO THE UPPER AND LOWER SECTIONS OF A ROTARY DRILL PIPE STRING, MEANS CONNECTING SAID COUPLING ELEMENTS FOR RELATIVE ROTATION, SAID MEANS INCLUDING LONGITUDINALLY SPACED UPPER AND LOWER COLLAR MEMBERS DISPOSED BETWEEN THE INNER AND OUTER COUPLING MEMBERS, SAID UPPER COLLAR MEMBER BEING SECURED TO SAID OUTER COUPLING MEMBER AND ROTATABLE ABOUT SAID INNER COUPLING MEMBER, SAID LOWER COLLAR MEMBER BEING SECURED TO THE INNER COUPLING MEMBER AND ROTATABLE RELATIVE TO SAID OUTER COUPLING MEMBER, AT LEAST ONE LONGITUDINALLY EXTENDING VANE SECURED TO EACH OF THE COUPLING ELEMENTS, THE VANES BEING ANGULARLY INTERSPERSED AND EXTENDING RADIALLY IN OPPOSED DIRECTIONS ACROSS THE ANNULAR SPACE BETWEEN THE COUPLING ELEMENTS INTO REOTATIONALLY SLIDABLE SEALING ENGAGEMENT WITH THE WALL OF THE OPPOSED COUPLING ELEMENTS WHEREBY TO DIVIDE THE ANNULAR SPACE BETWEEN THE COUPLING ELEMENTS INTO AT LEAST TWO ARCUATE CHAMBERS SEALED FROM EACH OTHER AND EXPANDABLE AND CONTRACTABLE IN RESPONSE TO RELATIVE ROTATIONAL MOVEMENT OF THE COUPLING ELEMENTS, PORT MEANS THROUGH THE WALL OF THE INNER COUPLING ELEMENT COMMUNICATING THE BORE THEREOF WITH THE INTERIOR OF ONE OF SAID CHAMBERS, AND PORT MEANS THROUGH THE WALL OF THE OUTER COUPLING ELEMENT COMMUNICATING THE INTERIOR OF THE OTHER OF SAID CHAMBERS WITH THE EXTERIOR OF SAID OUTER ELEMENT.