Releasable fluid control apparatus for retrieving subsurface well devices

Claim 1

IN COMBINATION: A DEVICE ADAPTED TGO BE DISPOSED IN A WELL BORE AND HAVING A DOWNWARDLY FACING SHOULDER; A MEMBER ADAPTED TO BE CONNECTED TO A RUNNING-IN STRING FOR MOVEMENT IN THE WELL BORE AND TO BE DISPOSED OVER THE DEVICE; LATCH MEANS CARRIED BY AND MOVABLE LONGITUDINALLY OF SAID MEMBER AND MOVABLE INHERENTLY INWARDLY TO A POSITION UNDER SAID SHOULDER TO BE ENGAGED THEREWITH; SAID MEMBER HAVING SHIFTING MEANS ENGAGING SAID LATCH MEANS WHEN SAID LATCH MEANS MOVES IN ONE DIRECTION LONGITUDINALLY OF SAID MEMBER TO HOLD SAID LATCH MEANS LATERALLY INWARDLY UNDER SAID SHOULDER AND IN COUPLING RELATION TO THE DEVICE; AND FLUID OPERATED MEANS RESPONSIVE TO THE PRESSURE OF THE FLUID IN THE WELL BORE EXTERNALLY OF SAID MEMBER FOR MOVING SAID LATCH MEANS IN THE OPPOSITE DIRECTION LONGITUDINALLY OF SAID MEMBER AWAY FROM SAID SHIFTING MEANS TO ALLOW SAID LATCH MEANS TO BE SHIFTED BY SAID SHOULDER LATERALLY OUTWARDLY TO UNCOUPLED RELATION FROM THE DEVICE.