The E 251, from 1970 class 251 or class 171 at Deutsche Bahn, was an electric locomotive that was specially developed for the Rübelandbahn in Saxony-Anhalt. Although the route had already been rebuilt in the 1930s, the slopes of the Harz Mountains still required gradients of up to six percent. Finally, in the 1960s, due to the increasingly heavy lime and ore trains, it was decided that the line should be electrified. In contrast to the remaining routes in Germany, this was done in the system with 25.000 Volts and 50 Hz, which led to the development of the E 251.

Based on the DR electric locomotives E 11 and E 42, this resulted in a more powerful, six-axle design whose systems were designed for the special power system. Since the route did not allow high speeds, the speed was reduced to 80 km/h. This further increased the tractive power and now also made a cheaper drive with nose-suspended motors possible. In addition, the tighter curves on the Rübelandbahn were taken into account with a special design of the chassis. Now it was possible to pull freight trains of 600 tonnes up the steep inclines, each with a train engine and a pusher engine. The total of 15 locomotives that were built proved themselves on this route and still pulled both freight and passenger trains in the days of the Deutsche Bahn. However, the latter fell away in 2000 due to new regulations on automatic door controls, until the class finally had to hand over its service in front of freight trains to modern multi-system locomotives in 2004.