“The FUM catenary renewal machine developed by Plasser & Theurer is also highly suited for the installation of high-strength grooved contact wires such as AC-150, CuMg 0.5” This is the conclusion of a study by Vienna University of Technology, Ao. Univ.-Prof. DI Dr. techn. Rudolf Heuer, Head of the Laboratory of Structural Model Dynamics at the Research Center of Mechanics and Structural Dynamics of the Institute for Building Construction and Technology. TU Wien examined the mode of operation of the FUM. The machine installs the contact wire and carrying cable under a defined final and constant nominal tension. The initial tension reduces vertical waves in the contact wire, which would otherwise have a considerable negative effect on the interplay between current collector and contact strip, affecting the quality of current collection significantly. The special design of the FUM friction winch unit made by Plasser & Theurer demonstrably prevents this. The FUM generates the tension in the wire gradually, taking the technological characteristics of the contact wire materials into account. The result is an optimal overhead line system with a contact wire under ideal initial tension, free of residual ripple, allowing train operation at the permissible maximum line speed immediately after the completion of the installation and without the need for re-tensioning.