Patent ID: 7004265

Claim:
A piston assembly for providing a fluid seal within an inner barrel assembly of a core barrel apparatus, the inner barrel assembly including an interior wall, the piston assembly comprising: a piston configured to provide a fluid seal between an outer cylindrical surface of the piston and the interior wall of the inner barrel assembly; at least one laterally movable locking element associated with the piston, the at least one laterally movable locking element configured to engage a cooperative structure of the interior wall of the inner barrel assembly when the at least one laterally movable locking element is at a first position and to disengage the cooperative structure when the at least one laterally movable locking element is at a second position; and a slidable piston rod associated with the piston, the slidable piston rod located and configured to maintain the at least one laterally movable locking element at the first position when the slidable piston rod is at one position, the slidable piston rod further configured for travel relative to the piston to another position where the at least one laterally movable locking element is free to move to the second position.