DBAG Class 425
Encyclopedia
The Classes 425 and 426 EMUs are a class of electric multiple unit
s built by a consortium of Siemens, Bombardier and DWA and operated by DB Regio
in Germany. They are essentially the same vehicle, but the class 425 EMU consists of four segments, while the class 426 EMUs only have two parts.
superstructure was built as flat as possible, both to minimize drag and to ease automated cleaning. The acceleration is achieved by distributing traction motor
s among eight of the train's ten axles including two of the three jacobs bogie
s.
The trains have become infamous for their braking problems: On slippery tracks, the original braking software tended to optimize rolling friction towards a local maximum rather than the absolute maximum, resulting in a severe loss of braking power. In some instances trains overran platforms and signals for several hundred meters. New software and sand sprinklers have solved these problems.
Electric multiple unit
An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages...
s built by a consortium of Siemens, Bombardier and DWA and operated by DB Regio
DB Regio
DB Regio AG is a subsidiary of Deutsche Bahn which operates short and medium distance passenger train services in Germany, and operates light and heavy rail infrastructure in the United Kingdom.-Germany:...
in Germany. They are essentially the same vehicle, but the class 425 EMU consists of four segments, while the class 426 EMUs only have two parts.
Description
It is a high-powered, light-weight vehicle with high acceleration for short- and medium-distance services with frequent stops. The aluminiumAluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
superstructure was built as flat as possible, both to minimize drag and to ease automated cleaning. The acceleration is achieved by distributing traction motor
Traction motor
Traction motor refers to an electric motor providing the primary rotational torque of a machine, usually for conversion into linear motion ....
s among eight of the train's ten axles including two of the three jacobs bogie
Jacobs bogie
Jacobs bogies are a type of rail vehicle bogie commonly found on articulated railcars and tramway vehicles....
s.
The trains have become infamous for their braking problems: On slippery tracks, the original braking software tended to optimize rolling friction towards a local maximum rather than the absolute maximum, resulting in a severe loss of braking power. In some instances trains overran platforms and signals for several hundred meters. New software and sand sprinklers have solved these problems.