Patent ID: 8753057

Claim:
A combination comprising a tightening member and at least one screw-fastener element, which combination is adapted for securing the at least one screw-fastener element to a mating fastener element with a predetermined tightening torque, the at least one screw-fastener element having a continuous engaging surface that extends continuously along a complete periphery of the at least one screw-fastener element and the tightening member having a corresponding continuous engaging surface that extends continuously along a corresponding complete periphery of the tightening member such that the tightening member is held both axially and in rotation relative to the screw-fastener element by tight-fit surface interference of the continuous engaging surfaces of the tightening member and the at least one screw-fastener element and such that the tightening member and the at least one screw-fastener element rotate with one another as continuously increasing torque is applied to the tightening member which is less than the predetermined torque, the continuous engaging surface of the tightening member including at least one peripheral spline complementary to at least one peripheral spline of the engaging surface of the at least one screw-fastener element, a projecting surface portion of the at least one peripheral spline of the tightening member being in tight-fit surface interference with a projecting surface portion of the at least one peripheral spline of the engaging surface of the at least one screw-fastener element when the tightening member and the at least one screw-fastener element rotate together, wherein the tightening member and the at least one screw-fastener element rotate relative to each other when a torque transmitted by the tightening member to the at least one screw-fastener element reaches the predetermined tightening torque and without destruction of the tightening member, whereby at the predetermined tightening torque, there is a maximum friction force between the projecting surface portion of the at least one peripheral spline of the continuous engaging surface of the tightening member and the at least one screw-fastener element beyond which there is no longer friction drive force between the continuous engaging surfaces of the tightening member and of the at least one screw-fastener element.