Abstract: A device is provided for tensioning lines (ropes, cables or wires). In order to improve a device for gripping and tensioning ropes, cables or wires, particularly in sheet or hoisting winches or windlasses, in tackles or pulley blocks or pulley lifting tackle, permanently or operationally interconnected coniform discs are provided which can be actuated by motor or by hand via a crank or a tackle line, and which exhibit surface contours, such that with only a single loop of the tensioning line a secure clamping effect of the coniform discs on cable put through in only a single loop is attained without the occurrence of wear or snapping of the tensioning line. Putting through and releasing (slackening) of the line is facilitated, and the improvement takes effect with respect to both rotation directions independent of the direction. The surface contouring of the discs is implemented as inwardly directed radial waves of the described form which are designed as straight lines or curves.