The E 44 was a four-axle electric locomotive for all train types, which broke new ground for German electric locomotive construction with its design and can be regarded as a model for almost all later classes. It was the first electric locomotive in Germany to be built in more than 100 units and the last examples were used in both German states until the 1980s.
The trend-setting feature of the E 44 was its chassis, consisting of two bogies, each with two axles and a nose-suspended motor. In previous series, the driven axles were usually in one or more main frames, sometimes even in bogies, but up until then most electric locomotives had running axles. Since the entire weight now rested on the powered axles, the total mass could be used as adhesive weight. Although the axle load of 19.5 tonnes was in the upper range for the time, the maximum hourly output of 2,200 kW represented a good value for this weight class. The transformer was housed in the engine room between the driver's cabs, and there were a few other electrical assemblies in short hoods. The same principle was applied to the general design and chassis of the six-axle E 93 and E 94. Initially, other express locomotives with powered axles in the main frame and additional carrying axles were developed, but eventually the design with bogies and no carrying axles also prevailed in the high speed range.
The production of the engines used by the Reichsbahn, which were primarily used in southern Germany, ran from 1932 to 1945, with a total of 174 units being completed. During the war, production was changed so that only local materials were used. From then on, the E 44 was known as “Kriegselektrolokomotive 1” (War Electric Locomotive 1, KEL 1) and the E 94 became “Kriegselektrolokomotive 2” (KEL 2). Since no new designs were initially permitted in the western occupation zones after the war and many E 44s had not survived the war, more examples were manufactured. In the end, however, only seven new ones were added in 1950 and 1951, and shortly afterwards the first new-build electric locomotives were built.
Four modified llocomotives were built as the E 244 for the Höllentalbahn in the Black Forest, which was electrified in the power system with 20,000 volts and 50 hertz. They were all designed to operate on steep grades and all had different electrical equipment. Among other things, different rectifiers and commutator motors were used. The E 244 01 was the only one without small hoods. After the conversion of the Höllentalbahn to the electricity system customary in Germany, one example was scrapped, one was taken to the German Museum and two were converted for operation under 15,000 volts. At the same time, road number E 244 21 received the equipment for operation under 25,000 volts in France.
Some conversions were made to adapt to new requirements. Some engines were given an electrically controlled tap changer so that they could be operated from a driving trailer. Others have been fitted with a dynamic brake for better use on inclines. These two variants were known as the E 44 G and E 44 W. From 1968 the locomotives became class 144 and the examples with dynamic brakes became class 145 .
In the later GDR, the existing E 44s, like all other electric locomotives and the overhead lines, were initially handed over to the Soviet Union. After they had been re-gauged there and used for trials, most returned to the Reichsbahn in a desolate condition. Due to the lack of locomotives, they were refurbished. Due to the condition of the route network and to reduce wear and tear, the top speed was temporarily reduced to 75 km/h. After being redesignated as class 244, they increasingly came into low-level service over time, until the last engunes still used in shunting operations were retired in 1991.