Voith and Knorr-Bremse Lead DAC Hybrid Coupler Testing for EU Freight

Europe’s rail freight is entering a new era. With hybrid couplers, DAC trials, and real-world testing, Voith and Knorr-Bremse are taking the lead.

Europe’s rail freight sector is taking a major step towards digitalisation with the successful testing of hybrid locomotive couplers, developed by Knorr-Bremse and Voith Turbo, which support both traditional and digital automatic coupler (DAC) systems. It's a critical milestone in the continent’s transition to a fully digital freight network, led by the Europe’s Rail Joint Undertaking under the TRANS4M-R Flagship Project 5.

Compatibility Breakthrough: DAC Meets UIC

According to a recent update by Knorr-Bremse on LinkedIn, hybrid coupler systems were successfully installed in Siemens Vectron locomotives as part of initial compatibility tests. These hybrid units — Knorr-Bremse’s Hybrid Link and Voith Turbo’s CargoFlex Hybrid — were able to couple seamlessly with both DAC-equipped and conventional UIC screw coupler wagons.

"This is a real game changer for the sector," stated Knorr-Bremse, noting that the successful DAC mode compatibility test demonstrated the technical feasibility of mixed operation between legacy and modern systems. As the testing phase concludes, measures for refinement and final installation are now in motion.

CargoFlex Hybrid: Voith’s Flexible DAC Solution

Voith Turbo’s CargoFlex Hybrid is considered a strategic interim solution for rail operators preparing for DAC integration. The hybrid system allows automatic coupling to DAC-compatible railcars and manual coupling to traditional wagons, with the coupler head easily adjustable between the two modes. As Markus Ilg, Senior Sales Manager at Voith Turbo, explains: "With the CargoFlex Hybrid coupler, we are putting operators in the position to become pioneers in this epoch-making revolution in rail freight transport." The system offers gradual migration and positions operators to join the EU-funded Pioneer DAC Trains programme — a two-year trial involving 100 test trains running across European corridors.

According to Voith Turbo, the DAC transformation will affect 23,000 locomotives and 450,000 freight wagons across Europe by 2030. Operators are encouraged to start with locomotive retrofits — a critical first step in managing the mixed-fleet phase during which both traditional and DAC systems will coexist. Thomas Spill, Director of Technical Service Rail at Voith Turbo, says: "Anyone wanting to continue to have flexible use of their locomotives needs a system that is compatible with both technologies. And that’s exactly what the CargoFlex Hybrid coupler offers."

Voith’s Competence Center for Locomotives in Kiel plays an important role in this rollout, offering end-to-end services — including feasibility analysis, installation, and regulatory support. The Kiel facility, with a rail siding and workshop infrastructure, ensures that retrofitting is done efficiently and with full safety compliance. Spill also notes that manual coupling using heavy draw hooks is not only labour-intensive but also dangerous, proving how DACs significantly enhance occupational safety — especially as Europe’s rail sector grapples with workforce shortages and aging infrastructure.

Siemens Mobility Joins the Push

In a parallel development, Siemens Mobility has selected Knorr-Bremse to provide braking and coupling systems for Munich’s next-generation S-Bahn trains. As confirmed in a Knorr-Bremse press release, this marks the first integration of coupling technology from Knorr-Bremse into a Siemens Mobility train project. Dr. Nicolas Lange, Board Member at Knorr-Bremse AG, stated: "We’re proud to contribute to boosting system efficiency and sustainability in the rail sector through innovative modular couplers and advanced braking systems."

With the hybrid systems now successfully tested, and operators preparing for Pioneer DAC Train participation, the EU’s transition to a digitally connected, safer, and more sustainable rail freight network is firmly in motion.

Sources: Knorr-Bremse; Voith Turbo; Siemens Mobility