Remarkably Unremarkable: Tensioning Systems in Urban Transport

With TENSOREX, PFISTERER had already established a compact and innovative tensioning solution for railway systems. One of its most popular areas of use? Narrow tunnels. When, in 2009, the Berlin and Leipzig transport authority were looking for a solution for its trams that was practically invisible but still robust, Pfisterer developed the TENSOREX C+. A compact spiral spring on the inside, and two discs and a maintenance-free, enclosed roller bearing on the outside.

At a glance

  • Automatic tensioning system for overhead lines on electric railways
  • Subtle appearance thanks to compact springs
  • Robust, maintenance-free mechanical system

The purely mechanical tensioning system has since become the benchmark for use in areas surrounded by historical buildings, cafés, and public meeting points. But was the low-key system robust enough? A four-week load endurance test with 86.400 load changes per day and a crash test at 30 kN with a sudden removal of load provided the evidence: Tension levels can easily remain reliable for 30 years and the material will also remain undamaged, even if the wire snaps. Power has been running uninterrupted along the tram lines in Berlin and Leipzig for years, no matter what the temperature.