Releasable screw and nut bearing mechanism

A releasable screw and nut bearing mechanism comprising a central internal threaded screw, an external nut coaxial therewith and provided with internal threads or circular grooves forming a socket, the outer diameter of the screw being smaller than the inner diameter of the nut in order to provide a free annular gap therebetween, a plurality of rolling members provided with threads or circular grooves on their outer peripheral surfaces disposed at spaced angular intervals in said annular gap and in engagement simultaneously with the external threads of the screw and the internal threads or grooves of the socket, means for recycling the rolling members to bring them into their original position when the relative angular movement of the screw in the socket has caused an axial movement of said rolling members equal to a thread of the screw, said socket comprising segments adapted to move radially apart to a disengaged position wherein the screw is free from any engagement with said rolling members at any time, whether the mechanism is stationary or rotating indifferently in one or the other direction, irrespective of the axial load applied thereto, and means which automatically cause re-engagement of the rolling members with the screw and the socket when the component parts of the socket are brought by axial centripetal movement to an initial operating position.