DB is planning the conversion of more than 300 diesel-hydraulic locomotives built in the 1970s, which are used by DB Cargo, to a diesel/battery hybrid electro-mechanical configuration. DB believes the planned conversion will be more economic than buying new locomotives and could extend the working lives of the locomotives concerned by 16-20 years whilst also reducing fuel consumption, emissions, and noise.
DB Systemtechnik has undertaken the development and design of the new system, which will see the existing diesel hydraulic transmission removed from the locomotives replaced by an advanced electro-mechanical “plantetary” gearbox.
The rebuilt locomotives will be able to operate via both direct diesel-mechanical transmission or diesel-electric transmission using energy saved in lithium-ion batteries - or a mixture of both power sources. Regenerative braking will be fitted to recover braking energy for reuse.
Toshiba has ten years of experience in the production of its branded SCiB lithium titanium oxide batteries for rail use - 25 type HD300 locomotives used by JR Freight in Japan have been rebuilt with these batteries in a project which reduced fuel consumption by 36% and cut nitrous oxide emissions by 61%.
Henschel has developed the 3.2 tonne "planetary gearbox" required for the project. This has 20 gears, 46 bearings and 50 litres of lubricating oil. Its purpose is to divide engine output into both mechanical power for propulsion whilst also enabling storage of any excess power via the battery system. The gearbox is also designed to enable operation using only battery power or only diesel mechanical power - or any variation of combination of the two.
As well as direct mechanical transmission of the power provided by the diesel engine, both the generator and two traction motors supplied by Toshiba will be directly connected to the planetary gearbox. These are in turn supplied with electricity via a Toshiba power traction convertor system.
Toshiba will also supply power control software enabling the hybrid system to operate and the locomotives will be equipped with traction batteries rated at 92kWh (773V dc) using SCiB technology.
The pilot project will involve rebuilding two existing DB class 294 locomotives at Cottbus works. These were upgraded with remote control equipment in the 1990s and re-engined with MTU 4000 8B engines between 2003 and 2005. Both the engines and remote control equipment will remain after the conversion to electro mechanical transmission hybrid operation.
The conversion work is now underway and the first locomotives will be extensively tested at various locations in Germany during 2017 - 2019.
DB Systemtechnik anticipates the rebuilt locos will consume 20% less fuel and reduce CO2 emissions by at least 20%. If the project is successful DB Cargo plans the conversion of more than 300 class 294/295 locomotives and evaluation of the scope for using the technology in smaller diesel hydraulic shunting locomotives.