Prussian ET 551/552 to 669/670 Altona

For the electrification of the suburban network of Hamburg and Altona, the Prussian State Railway ordered 60 two-car units to be delivered between 1905 and 1907. Their bodies were built like regular commuter cars, but had traction equipment for 6 kV at 25 Hertz. Each two-car unit was called a “Viertelzug” (“quarter train”) and in service, usually two to four of these were coupled together.

Each car had a two-axle bogie at the front and a single axle in the middle. 54 two-car units got their electrical equipment from AEG and had three powered axles in total. The six others had equipment from SSW, got series-wound motors and had only two powered axles in total. Starting in 1925, they were rebuilt, after this they all only had two traction motors. The last ones were retired by the Bundesbahn in 1952.