A self-securing fastening means for interacting with an external thread in order to apply a tensioning force to a component which is to be secured, with: • a screw nut, comprising a through-opening with an internal thread for screwing with the external thread, a drive for interacting with a tool for tightening the screw nut in a tightening circumferential direction in order to move the screw nut in an axial screwing-in direction in the direction of the component which is to be secured, • at least a first cam surface, which is provided on a lower face side of the screw nut or on an optional cam plate arranged beneath the lower face side of the screw nut and having an opening aligned with the through-opening, • an annular element arranged axially adjacent to the screw nut or to the optional cam plate, which annular element has an insertion opening, aligned with the through-opening of the screw nut, for the insertion of the external thread, and which has on an upper face side, facing the screw nut, at least a second cam surface, which engages into the first cam surface, in order to move the screw nut and the annular element axially relative to one another on a relative rotational movement between screw nut and the annular element, wherein the first cam surface and/or the second cam surface, viewed in the tightening direction, rise(s) counter to the axial screwing-in direction, • braking means for increasing the friction between the screw nut and the external thread, characterized in that • the screw nut or the optional cam plate has at least a first tightening stop surface, active in the tightening direction, for interacting with a second tightening stop surface of the annular element, so that the screw nut or the optional cam plate carries along the annular element upon force activation of the drive of the screw nut by the tool in the tightening direction in the tightening direction, in particular once the first cam surface has slid along the second cam surface, and • that the braking means are designed and constructed such that they prevent rotation of the screw nut upon rotation of the annular element counter to the tightening direction, in order that, when the annular element is subjected to the action of force counter to the tightening circumferential direction, the screw nut and the annular element are adjusted axially away from one another, in order thus for the screw nut and the annular element to be braced to a more pronounced extent in relation to one another. • a screw nut, comprising a through-opening with an internal thread for screwing with the external thread, a drive for interacting with a tool for tightening the screw nut in a tightening circumferential direction in order to move the screw nut in an axial screwing-in direction in the direction of the component which is to be secured, • at least a first cam surface, which is provided on a lower face side of the screw nut or on an optional cam plate arranged beneath the lower face side of the screw nut and having an opening aligned with the through-opening, • an annular element arranged axially adjacent to the screw nut or to the optional cam plate, which annular element has an insertion opening, aligned with the through-opening of the screw nut, for the insertion of the external thread, and which has on an upper face side, facing the screw nut, at least a second cam surface, which engages into the first cam surface, in order to move the screw nut and the annular element axially relative to one another on a relative rotational movement between screw nut and the annular element, wherein the first cam surface and/or the second cam surface, viewed in the tightening direction, rise(s) counter to the axial screwing-in direction, • braking means for increasing the friction between the screw nut and the external thread, • the screw nut or the optional cam plate has at least a first tightening stop surface, active in the tightening direction, for interacting with a second tightening stop surface of the annular element, so that the screw nut or the optional cam plate carries along the annular element upon force activation of the drive of the screw nut by the tool in the tightening direction in the tightening direction, in particular once the first cam surface has slid along the second cam surface, and • that the braking means are designed and constructed such that they prevent rotation of the screw nut upon rotation of the annular element counter to the tightening direction, in order that, when the annular element is subjected to the action of force counter to the tightening circumferential direction, the screw nut and the annular element are adjusted axially away from one another, in order thus for the screw nut and the annular element to be braced to a more pronounced extent in relation to one another.