Threaded fastener with improved resistance to backing out of a blind hole

A machine, being a threaded fastener with superior resistance to failure of pre-torque in blind holes, comprising:

• a) a threaded body, having a main axis, and consisting of two portions, namely a lower threaded body and an upper threaded body;
• b) said lower threaded body, having an outer threaded surface, and having a lower interfacing surface in loose contact with a corresponding upper interfacing surface of said upper threaded body, featuring one or more mechanisms selected from the group consisting of dog clutches, toothed clutches, loose dowel joints, or other equivalent mechanisms, whereby torque about said main axis of said threaded body may be transmitted between said lower threaded body and said upper threaded body, while simultaneously allowing substantial freedom of axial movement between said lower threaded body and said upper threaded body;
• c) said upper threaded body, having said upper interfacing surface;
• d) a head, connected rigidly to the upper threaded body, and provided with means to be forcibly rotated by hand-held or non-hand-held tools, selected from the group consisting of hexagonal-head drive surfaces about the perimeter, square-head drive surfaces about the perimeter, hexagonal recesses known commonly as Allen head recesses, slots, cruciform slots or recesses, or other common means for driving threaded fasteners;
• and
• e) a means for transmitting tensional forces between said lower threaded body and said upper threaded body, which can be activated or allow for the varying of said tensional forces at least one time after said machine is threaded into an internally threaded hole.