In the development of a single-axle drive for electric locomotives, one of the approaches was to use the Buchli drive, as used in Switzerland. The 21 examples of the series initially designated as the Bavarian ES 1 were equipped with it and put into operation by the Reichsbahn as the E 16. They were used by the Bundesbahn until 1980 and were still the only locomotives in Germany with this technical solution. The Buchli drive was characterized by the fact that one traction motor was located above the axle in the locomotive body and its power was transmitted by a one-sided mechanism on the axle. Power was again transmitted between the large gear wheel and the axle via coupling rods. This design is externally recognizable by the cover of the gear wheel. Although the technology was highly complex, the engines could be completely decoupled from the impacts of the ground.

Control was via a new type of linear mechanical tap changer, which had been used shortly before on the E 32. Its further development was later also used in the standard electric locomotives. The chassis of the first five locomotives was designed with two bogies, each consisting of one leading axle and two powered axles. This solution did not work, and so the following locomotives were designed with driving axles in a main frame and Krauss-Helmholtz bogies. The first five were also converted to this form directly afterwards.

The first ten machines were given the Bavarian designation ES 1 when they were delivered in 1926. They had an hourly and continuous output of 2,340 and 2,020 kW and were soon renumbered E 16 01 to 10. Seven more followed in the following year as road numbers E 16 11 to 17. Their output had increased to 2,580 and 2,400 kW respectively. Finally, four more machines were ordered in 1932 with the numbers E 16 18 to 21. Due to technical advances, the output was now 2,944 and 2,655 kW.

Despite their unusual propulsion technology, the locomotives were used for a very long time. Only two were lost in the war, all the rest were taken over by the Federal Railways. There only the E 16 12 had to be retired in 1967 due to an accident, all other 18 locomotives were redesignated in 1968 as class 116. These were retired between 1973 and 1980.

After many lines in central Germany had been electrified, the 2,800 kW E 17 was used there for the time being. However, these were shifted to the south when the important line between Munich and Stuttgart was also electrified. For this reason, the somewhat weaker E 04 was developed for the relatively flat routes in central Germany.

Like the E 17, the new locomotive was developed by AEG, but was given one less axle to accommodate the lower output. The now three powered axles were located with an asymmetrical wheelbase in the middle of the locomotive and were each connected to the motors directly above via a helical-spring gear. To carry the weight, a leading axle was attached under each end of the locomotive. The speed was initially set at 110 km/h, which was actually sufficient for the planned operations. After the E 04 09 reached 151.5 km/h on a test run with a load of cars, it and all other E 04s were approved for 130 km/h. The E 04 23, which was the last locomotive produced, was the only one to receive push-pull train controls a few years later.

23 examples were built, of which only two did not survive the Second World War. Due to their main area of application, 15 of the remaining vehicles came to the Reichsbahn of the GDR after the war, where they were used most frequently in front of passenger trains in the Halle and Magdeburg areas. The E 04 23 was used between Halle and Leipzig, where it benefited from its push-pull train controls. From 1970 they formed the class 204. Initially, the Bundesbahn had its home in Munich and later in Osnabrück. They became the class 104 in 1968 and remained in service until 1982.

SSW and Henschel developed the E 05 as a competitor to the E 04 when the Reichsbahn was looking for a light electric express locomotive for central Germany. This model was also a 1-C-1 locomotive with an output of just over 2,000 kW, which was built in different versions for 110 and 130 km/h. Like the E 04, the three prototypes of the E 05 each received three individually driven axles. The differences lay in the fact that the E 05 had only 1,400 mm large drive wheels, which were also less suitable for high speeds due to their design with nose-suspended motors and cheaper production and maintenance. Because both the main transformer and the traction motors were individually cooled, there were no thermal problems despite the higher speeds compared to the competition.

The different top speeds made it possible to use different complex chassis designs. On the E 05 001 and 002, the carrying axles were combined with the adjacent powered axle to form a relatively simple steering frame. In contrast, the E 05 103 (designated as E 05¹), which had a top speed of 130 km/h, used further developed Krauss-Helmholtz bogies. In addition, the middle axle was designed to be laterally displaceable by 15 mm, while it was still fixed in the frame on the first two machines. In terms of performance, the three machines could keep up with the E 04, but due to the nose-suspended motors and the chassis, the smooth running at high speeds left a lot to be desired in a direct comparison. It remained with the three vehicles, which were hardly ever used in the period that followed and mainly served as a replacement for electric railcars that had failed.

Since all three machines were still in the Central German network after the end of the Second World War, they had to be handed over to the Soviet Union. Two of them returned to the GDR in 1952, where they initially stayed in the scrap yard. Road number E 05 002 remained there until it was retired in 1962, and only road number E 05 103 was rebuilt in 1959. The latter was only in use for a few years, as the use of the single locomotive soon no longer paid off and it was also retired in 1964.

In the first planning phase of standard electric locomotives, the Reichsbahn still thought of models with large motors and rod drive, but at that time there were already different approaches for single-axle drives elsewhere. Thus, five prototypes were ordered for delivery in the years 1926-1928, among which this locomotive was. It was first designated E 18 01, but later redesignated E 15 01. Its sisters in the trials were the E 16 101, E 21 01, E 21 02 and E 21 51.

In the search for the optimal axle arrangement, the use of two bogies was tested in the E 18 01. These each consisted of a leading axle with 1,000 mm wheels and two powered axles with 1,400 mm wheels, with the leading axle being movably mounted within the bogie by means of a bissel frame. A coupling between the bogies was used to better distribute the forces. Instead of the originally planned higher arrangement of the traction motors with reduction gear and quill, the drive was finally designed as a nose-suspended motor with a simple reduction gear. To cool the engines, two fans were housed in the engine room, each of which directed the air to the two powered axles of a bogie. 

From the end of 1927, the test drives took place in Central Germany, especially on the Magdeburg-Halle route. The locomotive impressed with its smooth running and was able to meet its specification of pulling 600-tonne express trains on the flat at 95 km/h. From 1930 it was tested in heavy mountain use in Silesia, where it achieved monthly mileages of more than 10,000 km. The signs of wear on the chassis, which were first observed in the lowlands, increased, which ultimately led to the E 15 not being mass-produced.

Although the production locomotives of the E 17 with their 1-D-1 wheel arrangement that had already been produced in the meantime were more based on the E 16, the E 15 came back to Central Germany and continued to be used there. Since the new express locomotives of the 1930s were to be called E 18 in the future, based on the class 18 Länderbahn steam locomotives, road number E 18 01 was renamed E 15 01 in 1933. After the war it was sent to the Soviet Union as reparation, from where it returned to the GDR in 1952 together with many other locomotives, but due to its very poor condition it could no longer be used and was later scrapped.

The E 17 was the first of a series of electric locomotives for express service, which had a 1-D-1 wheel arrangement and were equipped with quill drives. It thus formed the basis for the E 18 with a top speed of 150 km/h and the E 19, which was produced in smaller numbers and had a top speed of 180 km/h, and each represented a milestone for its time.

After good experiences had already been made with the E 21 with the power transmission by means of a quill drive, this solution was also decided on for the new express locomotives to be developed. At 120 km/h, the maximum speed was in the range that the steam-powered express trains of the time also reached. The four double traction motors acted on drive wheels measuring 1,600 mm and achieved a total of 2,800 kW or a continuous 2,300 kW over an hour. The E 17 was primarily intended for medium express trains, but trains weighing 630 tonnes could also be pulled at 95 km/h on the flat.

The area of operation extended over southern Germany, the area then known as Central Germany and the Silesian routes. Since most of the 38 locomotives were saved to southern Germany shortly before the end of the war, the Bundesbahn subsequently received 26 units. Only a few pieces remained standing in the Soviet occupation zone or in Poland. From a total of three pieces in the later GDR, two were in the USSR until 1952 as reparations. After their return, these were refurbished into two operational locomotives together with the third locomotives. At the Bundesbahn, all E 17s were modernized in 1960/1961 and redesignated as class 117 in 1968. The last of them remained in service until 1980, while the two sisters had already been decommissioned by the Reichsbahn in 1968.

As early as the first half of the 1930s, the Reichsbahn noticed that electric locomotives would soon be needed for speeds well in excess of 120 km/h. The E 04 that had just been introduced could be approved for running at 130 km/h without any problems, but with its three traction motors it only achieved an hourly output of 2,190 kW. However, this was not enough to reach and maintain higher speeds with heavier express trains. As a result, two prototypes of a new locomotive were built in 1935, which could make up to 150 km/h with a chassis similar to the E 17 with an hourly output of 3,040 kW.

Despite the four powered axles mounted in the frame, it was possible to achieve smooth running at high speeds by combining the outer powered axles together with the adjacent carrying axle to form an AEG Kleinow bogie and thus being able to move laterally. Thanks to the return springs, the locomotives ran stably on track at any speed. Contrary to what was still common practice at the time, the power taps were not controlled by a steering wheel, but by an up-down control supported by an electric motor. This was accompanied by a seated position for the driver, whereas until then he had to stand in electric locomotives. A new feature was a streamlined locomotive body with low skirts at both ends. The latter caught large amounts of snow and dirt in winter, so they were later removed by the Bundesbahn and shortened by the Eastern Reichsbahn.

A total of 53 examples were put into service until 1939. Meanwhile, the E 18 was awarded a Grand Prix at the Paris World Fair in 1937, while in the country attempts to replace some of the engine's components with “native materials” failed. The planned use from Munich to Berlin could not take place in one go, since the different design of the overhead line in Central Germany would have required other pantographs. Instead, the locomotives were used in southern Germany, where many routes had already been electrified.

In 1937, the BBÖ ordered eight units with adjustments for use in the mountains as class 1870. These adjustments included a higher arrangement of the ventilation grilles to protect against snow and a reduction in the top speed to 130 km/h. After being incorporated into the Reichsbahn, they were taken over as the E 18² and some of the adjustments were reversed. After the war, these eight engines, together with a “real” E 18, remained in service for a very long time and underwent several modifications that brought them closer to the ÖBB standard. After a few changes of color scheme, the last ones were only removed from regular service in 1992.

In Germany, a total of 39 units remained with the Bundesbahn, of which 34 could be made operational again. The fleet was reinforced in 1953 by five purchased from the GDR, which had returned from the Soviet Union as former reparations. In the years 1954 and 1955, two more new locomotives were built. The E 18 became the class 118 from 1968 and was retired by 1984. Although the Reichsbahn in the GDR had already sold its five operational engines, between 1958 and 1960 the components of six damaged machines parked in Hennigsdorf were put together to form a total of three operational engines. Two of them were later converted to a speed of 180 km/h in order to be able to test new vehicles. The last one was not retired until 1991.

The E 18, manufactured from 1935, was already a step forward in terms of top speed and performance compared to the earlier electric locomotives, but the Reichsbahn was already planning to operate at even higher speeds at this point. The goal was a non-stop connection from Berlin to Munich at speeds of up to 180 km/h. The 2.9 percent of the Frankenwaldbahn had to be overcome, which required sufficient power. Therefore, in 1937, the Reichsbahn ordered road numbers E 19 01 and 02 from AEG and road numbers E 19 11 and 12 from SSW.

The locomotives were designed differently, but all represented a further development of the E 18 and also looked very similar to it. Since even higher speeds were planned for the future, the locomotives were technically designed for speeds of up to 225 km/h. The hourly output was 4,000 kW for the AEG locomotives and 4,080 kW for the SSW locomotives. More welded parts were used than before and a more powerful brake system and a dynamic brake were installed. Locomotives 11 and 12 differed significantly from the E 18 and had, among other things, double motors. The transformer windings were made of aluminum to reduce dependence on copper imports. Since these were very prone to failures, they were later replaced with copper.

Intensive test runs were undertaken with the locomotives, during which power levels of over 5,000 kW and speeds of around 200 km/h were reported. It soon became apparent that, despite the reinforced braking system, the distant signal distance of 1,000 meters could no longer be maintained at such high speeds, which made operation without technical aids too unsafe. Due to the cessation of express traffic at the beginning of the war, there was no series production of the E 19. After the war, all were stationed in Nuremberg by the Bundesbahn and used in commercial operation. Since high speeds were no longer required and were initially not possible on the existing network, the maximum speed was limited to 140 km/h. They were listed as class 119 from 1968 and retired between 1975 and 1978. Today, two locomotives are preserved in a museum, namely the E 19 01 in Berlin and the E 19 12 in Koblenz-Lützel.

The E 21⁰ included two of the five electric express locomotives that were procured between 1926 and 1928 to test the single-axle drive (see E 15). In contrast to the E 15 and E 16, these, like the E 21 51, had seven axles. It was the asymmetrical wheel arrangement 2-D-1 and also an asymmetrical body. Each of the four axles mounted directly in the main frame was driven by two motors, which passed on their power via a helical-spring gear. This was a form of quill drive in which the spokes were cushioned relative to the hollow shaft. This reduced both the bumps from the tracks and the jerky changes in torque when starting off.

At one end of the locomotive, the body formed a flush finish and underneath was a two-axle bogie. At the other end there was a half-height hood in front of the cab and a single carrying axle. On the E 21 01 this was still designed as an individually movable Bissel axle, but on the E 21 02 it was combined with the adjacent driving axle to form a Krauss-Helmholtz bogie, which improved the running characteristics in curves.

Test drives showed that even the first locomotive was significantly more powerful than the specifications had envisaged. A speed of 95 km/h could be reached on the flat with express trains of up to 1,905 tonnes, which was more than three times the required weight. It could reach its top speed of 110 km/h with trains of up to 1,050 tonnes, which was still much heavier than most express trains.

The second was ordered while the first model was being tested. After testing, both went into regular service in the Giant Mountains and stayed there until the end of the war. They then came to the Soviet Union as reparations until they returned in 1952 and 1953 and were temporarily parked. After around seven years of service, they were refurbished by the Reichsbahn, but were only used occasionally in the years that followed. A few years later, enough new electric locomotives had been delivered, which meant that not only the old machines with rod drives became superfluous, but also small classes with single-axle drives. Both were parked again in 1965, officially retired in 1966 and finally scrapped in 1967.

The E 21 51 was one of the electric locomotives with single-axle drive procured at the end of the 1920s, which was assigned to the same series due to the structural similarity with the E 21 01 and 02. In contrast to these, however, it was built by Linke-Hoffmann-Busch and Bergmann and differed significantly from its sisters in terms of appearance and, above all, technical details.

Like these, it also had a 2-D-1 wheel arrangement, two small motors per powered axle and a top speed of 110 km/h, but these were the only similarities. Their power was chosen to be as high as the four driving axles would allow. At 1,400 mm, the diameter of the driving wheels was 350 mm smaller than on the E 21⁰, which was compensated for by a higher gear ratio. The car body was constructed symmetrically and was flush with the driver's cab at both ends. Compared to other electric locomotives of the time, the fronts were slightly rounded to create less drag. In contrast to the power transmission, this feature was adopted in a similar form in later locomotives such as the E 18 and E 19 and also in the new locomotives after the war.

The axles were initially driven via a reduction gearbox, which was not particularly convincing in terms of smooth running. After a short time, teeth broke and spokes cracked, which is why a new power transmission via hollow shaft was installed. This also proved its worth, but the decision had already been made in favor of the helical-spring gear at that time.

Like the two examples of the E 21⁰, the E 21 51 was used in the Giant Mountains and was rescued to Central Germany in the last months of the war. In the end, it too had to be handed over to the Soviet Union and returned to the GDR at the same time as the others. However, it was parked without being refurbished and finally retired and scrapped together with its sisters.

To mark the 50th anniversary of the Staatsspoorwegen in the Dutch East Indies, the line between Batavia (today Jakarta) and Buitenzorg (today Bogor) was electrified in 1925. Direct current with 1,500 volts was used and the required locomotives were obtained from different manufacturers in the Netherlands, Germany and Switzerland. For use in front of express trains on the flatter routes, four six-axle locomotives were used, the mechanical part of which came from SLM and the electrical part from BBC.

The Java bogie was used for the first time on these locomotives, which SLM later successfully used on several locomotives. In addition to the two driving axles fixed in the middle of the frame, there was one of these bogies at each end of the locomotive, each consisting of a leading and a driving axle. The pivot point was close to the driving axles, so that the one-sided Buchli drive could also be attached to these driving axles. 

In the years 1924 and 1927 two of these vehicles were delivered each, which were given the numbers 3001 to 3004. At the KAI they were later given numbers 1 to 4. They remained in service throughout their lives on the same line and were retired in 1976 after being replaced by Nippon Sharyo EMUs.