Once upon a time, shortly after 1971, after having successfully introduced a new system of first-class-only express trains (the InterCity system), Deutsche Bundesbahn saw that it was good. Then they set out for new shores: high speed. Yes, technically some trains were high-speed, as the 103 could power light trains at 200 km/h. But there was no real dedicated high speed train, and so DB thought that a light-weight high-speed EMU would be a nice idea.
What happened then looks only superficially like a very strange idea: the design for the new EMU was based on an S-Bahn train of all things, namely the 420 EMU. The resulting ET 403 (ET means "Elektrotriebwagen", i.e. EMU) was decades ahead of its time: a streamlined, ultra-light-weight all-aluminium four-car tilting train with automatic bumper coupling and pneumatic suspension. All axles were driven and the electric installations hid under the floors and over the roofs of the cars. It looked a little like Donald Duck (which was to become its nickname) and it could accelerate to 200 km/h in two minutes.
Only three were ever built (by AEG, BBC, LHB, MBB, MAN and Siemens). They went into regular service in 1973, but no further acquisitions were made - for several reasons: the dining compartment and pantry were too small; the tilting technology made people sick and thus had to be kept deactivated; there weren't many lines in DB's network where high-speed was of use; and all in all, the vehicles were too expensive to acquire and maintain. DB decided to go back to loco-driven trains, and thus the ET 403s were retired when the InterCity system went two-class in 1978. High-speed service with EMUs would come back, though: see InterCity Express.
Beginning with 1983, the ET 403 saw active duty again in a DB-Lufthansa cooperation where high-speed trains would replace short-range transfer flights. Aluminium/iron contact corrosion struck the final blow: all ET 403s had to be retired in 1991. Deutsche Bahn tipped their hat to this legendary vehicle around 2000 by labeling the ICE 3, the first ICE to be a real EMU with more than two powered cars, Baureihe (Class) 403.
Technical fact sheet:
- Concept: Bo'Bo'+Bo'Bo'+Bo'Bo'+Bo'Bo' layout (four cars with four axles in two bogies each), all axles driven; complete electrical installation in every car, pantographs only on end cars, high-voltage lines between cars; up to three units could be MUed together
- Power: 3840 kW
- 200 kN maximum
- Top speed: 220 km/h, 200 km/h in regular service
- Total weight: 235 tonnes (between 14.5 and 15.6 tonnes per axle)
- Length: 109.22 m
- Width: 2.80 m
- Height over rail: 4.02 m
- Suspension: pneumatic; the suspension bellows doubled as tilt actuators
- Maximum tilt angle: 4° in theory, limited to 2° by the pantographs; tilting switched off in practice because it made passengers feel uncomfortable
- Seats: 159 (all first class), 24 in restaurant