A coupling device having a first member provided with threads, a second member having an opening into and out of which the first member is inserted and removed, threaded elements within the second member mounted for movement between a first position where the first member may be threaded with the second member and a second position where the threaded elements have a diameter larger than the diameter of the threads of the first member permitting the first member to slide axially in and out of the second member, pull/lock/torque pins associated with the threaded elements and a manually operable mechanism for moving the threaded elements longitudinally into engagement with the pins expanding the threaded elements to their second position. The second member including an outer body provided with oval openings through which the pull/lock/torque pins pass and the threaded elements may include oval indentations against which the ends of the pull/lock pins abut, and wherein the threaded elements may include shoulders against which the pull/lock/torque pins abut.

A male coupling with movable threaded segments, consisting of a shaft, a sleeve mounted to move along the shaft, a plurality of threaded segments surrounding the shaft and mounted to move inwardly and outwardly relative to the shaft to effectively vary the outer diameter of the assembled threaded segments, the sleeve and threaded segments including surfaces adjoining each other such that movement of the sleeve in one direction causes the threaded segments to move inwardly toward the shaft, and a spring resiliently urging the threaded segments outward.