Core barrel head assembly and method

A method in earth drilling, the method comprising:

• providing a core head barrel comprising
• an upper body comprising a central passage,
• a pair of latches arranged in the central passage, wherein each latch comprises a hook at a first end and a pivot point on an outside surface in the hook, and wherein the hook of each latch extends through a hook slot such that the latches rotate about the pivot point and each latch pivoting about the pivot point at the first end, each latch comprising a latch release at a second end and an outer tube surface engaging surface between the first end and the second end, a retracting case including a first end configured to engage at least the latch release of the latches, and
• inserting each latch through a slot in the upper body such that the hook extends around a bridge in the upper body;
• and
• rotating the latches about the pivot, thereby bringing the second end of the latches toward the core barrel head assembly
• wherein the outer tube surface engaging surface of each latch extends through a latch slot in an outer wall of the upper body and such that the latches rotate about the pivot point, and wherein the latches are movable between an extended position and retracted position by the retracting case with a mechanical advantage;
• engaging the core barrel head assembly with an overshot;
• and
• removing the core barrel head assembly from a hole.