Earth boring equipment including two part rotary cutting head

Claim 1

IN A DRILL HEAD FOR SUBSURFACE EXPLORATION, HAVING A HOLLOW OUTER PART PROVIDED WITH A CENTRAL OPENING AT ONE END, CUTTING BITS MOUNTED ON SAID HOLLOW OUTER PART AROUND SAID CENTRAL OPENING, MEANS FOR CONNECTING A HOLLOW DRILL STRING TO SAID HOLLOW OUTER PART, A PASSAGE IN SAID HOLLOW OUTER PART FORMING A CONTINUATION OF THE PASSAGE IN SAID HOLLOW DRILL STRING, A PLUG-LIKE INNER PART SELECTIVELY MOUNTABLE AND DEMOUNTABLE IN SAID HOLLOW OUTER PART, SAID PLUG-LIKE INNER PART BEING SLIDABLE THROUGH THE DRILL STRING AND INTO SAID PASSAGE FOR CLOSING SAID OPENING, AND A PILOT BIT CARRIED BY SAID PLUG-LIKE INNER PART AND PROTRUDING FROM SAID OPENING, THE IMPROVEMENT COMPRISING, (A) SHOULDER MEANS ON SAID PLUG-LIKE INNER PART AND IN SAID PASSAGE ENGAGEABLE TO LIMIT MOVEMENT OF SAID PLUG-LIKE INNER PART INTO SAID HOLLOW OUTER PART, (B) RETRACTABLE LATCH MEANS BETWEEN SAID PLUG-LIKE INNER PART AND SAID HOLLOW OUTER PART INCLUDING A PASSAGE IN AND TRANSVERSE OF SAID PLUG-LIKE INNER PART, A PASSAGE AXIALLY OF SAID PLUG-LIKE INNER PART INTERSECTING SAID FIRST PASSAGE, A LATCH PIN SLIDABLY MOUNTED IN SAID TRANSVERSE PASSAGE, A CAM SURFACE ON SAID LATCH PIN DISPOSED IN SAID AXIAL PASSAGE, A CIRCUMFERENTIAL CHANNEL IN THE PASSAGE-DEFINING INNER WALL OF THE SAID OUTER PART AND OPENING INTO SAID PASSAGE FOR RECEIVING SAID LATCH PIN, AND SPRING MEANS MOUNTED WITHIN SAID TRANSVERSE PASSAGE IN THE PLUG-LIKE INNER PART ADAPTED TO URGE SAID LATCH PIN INTO SAID CHANNEL, (C) A KEY IN SAID CHANNEL ENGAGED BY SAID LATCH PIN TO HOLD PLUG-LIKE INNER PART AND SAID OUTER PART AGAINST RELATIVE ROTATION WHEN HELD AGAINST RELATIVE AXIAL MOVEMENT BY ENGAGEMENT OF SAID PATCH PIN, AND (D) AN OPERATOR MOVABLE IN SAID PASSAGE AXIALLY OF SAID INNER PART AND HAVING A PART ACCESSIBLE THROUGH SAID HOLLOW DRILL STRING, MEANS ON SAID OPERATOR COOPERATING WITH SAID CAM SURFACE ON SAID LATCH PIN FOR RETRACTING SAID LATCH AND FOR WITHDRAWING SAID PLUG-LIKE INNER PART FROM SAID CUTTING HEAD AND DRILL STRING TO THEREBY OPEN SAID THROUGH PASSAGE FOR SAMPLE TAKING OPERATIONS.