The Prussian State Railways had a total of ten electric double locomotives running under the numbers EG 551 to EG 570, which were built for freight service on topographically challenging lines. Instead of designating the parts of the locomotives with the same running number and the suffix a/b/c, as in the case of the EG 538 etc., each half of the locomotive was given its own number in this class. This is an indication that these were independent vehicles that contained all the required parts. However, two identical locomotives were always permanently coupled in operation and formed a unit.
Each half of the locomotive consisted of a three-axle chassis on which the cab was arranged in the middle. Here, too, the space behind was used for a luggage compartment, so one can speak of baggage locomotives. This entire interior was made of wood, but covered with sheet metal on the outside.
In addition to a force-ventilated transformer and cooling systems, the front hoods also housed the remaining electrical equipment, all of which were supplied by BBC. The hoods were flush with the roof of the cab and the luggage compartment and were only slightly narrower than these. Thus, even with these locomotives, there was only a narrow field of vision on both sides of the cab. A double traction motor was flexibly suspended within the chassis between the second and third axles. The power was transmitted via a countershaft to the jackshaft and finally via connecting rods to the axles. Since the chassis had an outside frame, Hall cranks were used.
Although the order for the locomotives had already been placed in 1912, production and introduction into service were delayed by a few years due to the war. Thus, the first one was not ready for service on the Silesian Mountain Railway until 1919. Due to the low axle load, it was also possible to use the locomotives off the main line. There they could even be seen with passenger trains, while the speed on the main line was only sufficient for freight trains.
The Reichsbahn classified them as E 905 and gave them the numbers from E 90 51 to E 90 60. From now on, each double locomotive had only one serial number, while the halves were designated a and b. With the advent of more powerful and faster electric locomotives, they were increasingly forced out of service with heavy trains, followed by the first withdrawals. After the Second World War there were still three, all of which had to be handed over to the Soviet Union. Together with other locomotives they came back to the GDR in 1952/1953, but had to be scrapped a short time later due to their desolate condition.