Safety joint for oil well drilling string

Claim 1

A RELEASING TOOL, WHICH COMPRISES A PAIR OF PARALLEL ELONGATED ELEMENTS CAPABLE OF MOVEMENT BOTH LONGITUDINALLY AND ROTATIONALLY RELATIVE TO EACH OTHER WHEN IN PREDETERMINED POSITIONS RELATIVE TO EACH OTHER, A PLURALITY OF INDIVIDUAL KEYS PROVIDED ON ONE OF SAID ELEMENTS IN ALIGNMENT LONGITUDINALLY OF SAID ONE ELEMENT AND SPACED FROM EACH OTHER LONGITUDINALLY THEREOF, A PLURALITY OF INDIVIDUAL KEYS PROVIDED ON THE OTHER OF SAID ELEMENTS IN ALIGNMENT LONGITUDINALLY OF SAID OTHER ELEMENT AND SPACED FROM EACH OTHER LONGITUDINALLY THEREOF, THE DIMENSION OF EACH OF SAID LAST-MENTIONED KEYS LONGITUDINALLY OF SAID OTHER ELEMENT BEING LESS THAN THE CORRESPONDING SPACE BETWEEN EACH PAIR OF ADJACENT KEYS ON SAID ONE ELEMENT, THE SPACES BETWEEN SAID KEYS ON SAID ONE ELEMENT CORRESPONDING TO THE POSITIONS OF SAID KEYS ON SAID OTHER ELEMENT WHEREBY SAID KEYS ON SAID OTHER ELEMENT MAY MOVE BETWEEN SAID KEYS ON SAID ONE ELEMENT DURING ROTATION OF SAID ONE ELEMENT AND OTHER ELEMENT RELATIVE TO EACH OTHER WHEN SAID ELEMENTS ARE IN PREDETERMINED LONGITUDINAL POSITIONS RELATIVE TO EACH OTHER, MEANS PROVIDED ON SAID ONE ELEMENT TO STOP THE RELATIVE ROTATIONAL MOVEMENT OF SAID OTHER ELEMENT WHEN SAID KEYS ON SAID OTHER ELEMENT HAVE ROTATED PAST SAID KEYS ON SAID ONE ELEMENT AND MAY THEREFORE SHIFT LONGITUDINALLY RELATIVE TO SAID ONE ELEMENT TO LOCK POSITIONS AT WHICH SAID KEYS ON SAID ELEMENTS ARE CIRCUMFERENTIALLY ADJACENT EACH OTHER, SPRING MEANS CONNECTED BETWEEN SAID ONE ELEMENT AND SAID OTHER ELEMENT TO SHIFT SAID ELEMENTS LONGITUDINALLY RELATIVE TO EACH OTHER UNTIL SAID KEY ELEMENTS ARE IN SAID CIRCUMFERENTIALLY ADJACENT LOCK POSITIONS, THRUST MEANS TO PREVENT SHIFTING OF SAID ELEMENTS RELATIVE TO EACH OTHER PAST SAID LOCK POSITIONS AT WHICH SAID KEYS ARE CIRCUMFERENTIALLY ADJACENT EACH OTHER DESPITE THE CONTINUED BIAS OF SAID SPRING MEANS, AND STOP MEANS TO LIMIT THE LONGITUDINAL MOVEMENT OF SAID ONE ELEMENT AND OTHER ELEMENT RELATIVE TO EACH OTHER WHEN SAID ELEMENTS ARE IN SAID PREDETERMINED LONGITUDINAL POSITIONS RELATIVE TO EACH OTHER.