Press Release
Metro Gearboxes for Hamburg: ZF Supplies Technology for Germany’s Largest Subway Project
- Major order for almost 3,000 gearboxes over a period of around 15 years
- Quiet, powerful, reliable: Gearboxes for the DT6 vehicles impress with their noise- and weight-optimized design
- ZF and Alstom: Strong partnership of around four decades
Friedrichshafen / Hamburg. Germany's largest subway project will start operations with ZF driveline technology. For the new U5 subway line and for the modernization of the existing fleet, Hamburger Hochbahn has placed an order with Alstom for 374 new rail vehicles. They will be equipped with ZF's newly developed two-stage spur gear drive – a total order volume of 2,992 units. The project continues the nearly four-decade-long partnership between ZF, vehicle manufacturer Alstom and the Elbe region.
24 stations along more than 29 kilometers of track, fully automated and driverless service running at 90-second intervals, around 315,000 passengers per day, according to conservative estimates: The new U5 line of the Hamburger Hochbahn is a key pillar in Hamburg's mobility transition. "With this volume of journeys and passengers, everything has to mesh perfectly," says Markus Gross, Head of the Rail Drive Systems product line at ZF. After all, with roughly 15 years of construction, the U5 is Germany's largest subway project. Accordingly, the expectations placed on the technology used are very high. "Anyone operating a cosmopolitan public transport system needs driveline technology that lives up to that standard. And this is exactly what we are now providing to support our partner Alstom and the City of Hamburg."
To meet the demand of the new metro line, Hamburg has also ordered an entire fleet of new-generation DT6 electric multiple units from Alstom. ZF, in turn, is supplying a specially developed gearbox for this new generation of vehicles. The new DT6 vehicles will not only be operated on the U5 line, but also gradually replace parts of the existing fleet across the rest of the network.
Tried-and-tested, reliable, remarkably smooth: ZF's spur gear drive for Hamburg's new U5
ZF has developed the new gearbox for the DT6 from scratch. The two-stage spur gear drive can handle a maximum axle load of 10,000 kg and process an engine output of 95 kW or an engine torque of 378 Nm at 2,400 rpm. ZF placed particular emphasis on noise behavior. The gearbox operates with exceptionally low noise, thanks to engineers optimizing both the housing contour and the gearing. The housing itself is made of aluminum, which reduces the weight. As a result, the dry system only weighs around 210 kg. Compared to competing products, the spur gear drive also requires less oil which not only saves resources but also reduces the required maintenance effort and the associated costs. This is also supported by the fact that removing the gearbox from the wheelset axle is easier than before thanks to a defined separation plane through the output. Thanks to this, the respective vehicle's wheels can be overhauled with less effort reducing vehicle downtime and ensuring smooth operation.
ZF produces the new gearbox at its location in Friedrichshafen and delivers it to Alstom. On behalf of the City of Hamburg, the French company is installing the transmission in the new DT6 rail vehicles. In the first call-off, ZF will produce 384 gearboxes for 48 vehicles. The first test gearbox will be delivered at the end of 2026, the production models as of the first quarter of 2027.
After the initial batch of 48 vehicles, another 20 units are planned annually as a follow on option. Over a period of around one and a half decades (mirroring the overall construction time of the U5 line), ZF will produce a total of 2,992 gearboxes and deliver them in series.
ZF and Alstom: Strong partnership for the Elbe region
"When the U5 starts passenger service as planned in 2029, we will be able to look back on more than four decades of partnership between our companies and the city of Hamburg," says Markus Gross. After all, the cooperation between ZF and Alstom for Hamburger Hochbahn dates back to 1987. Back then, Hurth (which later became part of ZF) was already producing gearboxes for the DT4 vehicle type on behalf of Bombardier (which was taken over by Alstom). Gearboxes for the DT5 followed between 2008 and 2022.
"We have had good experience with gearboxes from ZF in Hamburg. In terms of reliability, smooth running and service quality, they are exactly what we once again need for our demanding operation on the new U5 line," says Jörg Petersen, Head of Rail Vehicles at Hamburger Hochbahn AG.
"Together, we have already brought generations of Hamburg residents and countless tourists safely and comfortably to their destinations – and we will continue to do so. That is something we can truly be proud of," Gross says.
