After the First World War, the Reichsbahn operated the route in the Giant Mountains between Hirschberg (today Jelenia Góra) and Polaun (today Korenov) in cooperation with the CSD. The Prussian EG 551/552 to EG 569/570, which were actually designed for freight trains, were used for passenger transport, which was a major cost factor in relation to the very low passenger density in some sections. In addition, on the Czechoslovak section of the route, the CSD billed the usage fees according to axle-kilometres. This economic imbalance was to be ended by the introduction of railcars.

For the first time, a self-supporting car body in all-steel construction was realized on a railcar. The transformer with an output of 500 kW was located in its own compartment in the middle of the car body. A maximum of 468 kW of this went to the two suspension motors, which were each located on the inner axle of the two bogies. At the ends of the carriages, in addition to a gangway door, there was also the wiring for multiple controls and an electric train heater. The passengers quickly gave the railcars the nickname “Rübezahl”, after a mountain spirit from the Giant Mountains.

Eleven power cars and a total of 40 two-axle standard passenger cars were procured as trailers. Usually two railcars with eight trailer cars coupled in between were used and on less frequented sections one railcar was sometimes uncoupled and used alone. From 1934 the vehicles were also used on the Giant Mountain Railway to Krummhübel and the trailers were exchanged for a total of eight driving trailers, which were referred to as ES 89, analogous to the power cars. In 1945 three pieces came to Bavaria, where one of them was used until 1959. After the end of the war, the rest were located in the former German territory in what is now Poland and were not used by the PKP. There, the usable part of the electrics was removed and the rest of the vehicles were scrapped after 1954.