When the line from Freilassing over Bad Reichenhall to Berchtesgaden was electrified as one of the first in Bavaria, the State Railways ordered a number of locomotives for testing. These had to cope with gradients of up to 4.08 percent and curve radii of 180 metres. Among these were two four-axle locomotives for freight service built by Krauss with the electric part from Bergmann. They were among the first in Germany with single-axle drive and no carrying axles. 

Although they became known as EG 1, they were originally called EG 4x1/1 due to the four individually driven axles. With an hourly output of 1,074 hp and a top speed of 50 km/h, they were well suited for freight traffic on this line. Additionally, the absence of leading or trailing axles reduced the total length. After the successful trials, they were put into regular freight service. The Reichsbahn designated them E 73⁰. Their careers ended in 1937 and 1941.

Another type of electric locomotives imported from abroad in the 1980s was the 8K, supplied by Alstom. The reason for ordering a heavy goods train locomotive was the lack of capacity to haul large quantities of coal, which was urgently needed in Shanxi Province in particular. In order to be able to achieve sufficient traction with two-axle bogies, the 8K was designed as a double locomotive with two four-axle sections. The basis used was the BB 15000, which had been used by the SNCF since 1971. 148 units were delivered from France and two more were built in the Zhuzhou locomotive works in order to gain knowledge of modern technology.

Visually, the locomotives built for China differed from their originals in that they lacked the “Nez Cassé”, i.e. the bent fronts. In terms of power train technology, the biggest difference was that each axle had its own motor and not the typical French monomotor bogies were used. As with the 6K, traction motors with 800 kW each were used, resulting in a total output of 6,400 kW. The top speed was also set at 100 km/h.

As planned, the locomotives were mainly used to pull coal trains, which usually weighed around 4,000 tonnes. Later, train weights of 6,000 tonnes with one locomotive or 10,000 tonnes with two locomotives were tested. Although the power of the locomotives was sufficient, only the tests with 6,000 tonne trains were successful. With the heavier trains, it had been shown that the couplings were not up to the loads. Outside of their normal area of operation, the 8Ks were also used to haul passenger trains during the Chinese New Year celebrations, when passenger traffic was extremely high. The retirement took place between 2010 and 2015 due to the increasingly serious lack of spare parts. Four examples have been preserved for posterity, but not in working condition.

The SS1 was the first mainline electric locomotive to be manufactured in China. The “SS” stood for “Shaoshan”, Mao’s birthplace. The first seven prototypes with the designation 6Y1 were built between 1958 and 1966 with Soviet help and were based on the ВЛ60. In the area of electronics, experience from the 6Y2 supplied by Alsthom was also incorporated.

In the years that followed, the prototypes were continuously improved. The actual production locomotives were ultimately only built between 1980 and 1988. Including all prototypes, 826 SS1s were built, which were used for various types of trains and the first of which had reached the end of their service life after almost 30 years. The last one ran for the last time on September 19, 2014.

The SS4 is a member of the third generation of electric locomotives built in China. Built for heavy freight service due to growing demands in the eighties, it is a two-section locomotive with a total of eight axles. It delivers 6,400 kW and has a starting tractive effort of 628 kN, at a top speed of 100 km/h. Three prototypes were designed and built by Zhuzhou in 1985 and production was started in 1989. After 158 of the original variant, production switched to the improved SS4G. This incorporated a more modern electrical part that used advancements from the imported 6K and 8K locomotives. A total of 1,474 SS4G were built at Zhuzhou, Datong, Ziyang and Dalian.

The SS4B is a variant with completely overhauled electrical part built between 1995 and 2010. Due to their higher price, the 260 locomotives were only used by Shenhua Group for heavy coal traffic. Finally, there is the SS4C of which only two were built in 1997. These have an axle load of 25 instead of 23 tonnes to increase traction on freight trains of 5,000 tonnes. But no further locomotives of this variant were built since the increased axle load alone did not substantially improve haulage capacity.

In 1921 ALCO-GE built twelve electric locomotives for the Paulista of which eight were designed for freight traffic. The first line that had been electrified with 3 kV DC was the one between Jundiahy and Campinas that was 45 km long and had inclines of 1.8 percent. The main reason for electrification was that fire wood for steam locomotives had become scarce and good coal was difficult to obtain.

The freight locomotives had two two-axle bogies with a 420 hp traction motor on each axle and a boxcab body that led to the nickname “Quadradinha”. Haulage capacity on 1.8 percent inclines was 700 tonnes at speeds between 19 and 26 km/h. When running downhill, they could use their regenerative brake. Originally numbered 204 to 211, they were later renumbered to 401 to 408. When FEPASA was founded in 1971, they became class 6400. They were withdrawn between 1974 and 1978.

Although the classes 499.0 and 499.1 were also used in front of freight trains, the tractive effort in this role was limited. When the E 499.157 was damaged in an accident, the opportunity was taken to provide it with a different gear ratio for a top speed of 90 km/h as part of the repairs. Due to the limited adhesion, the starting tractive effort did not increase, but bigger pulling power was available at the usual speeds for freight trains. Although this locomotive was dismantled after testing, 85 examples of the new freight version were built in 1960 as the class E 469.1. These locomotives also had electric train heating and could therefore also pull passenger trains, but this only happened rarely due to the lower maximum speed.

When there was a further need for freight locomotives for 3.000 volts direct current, another series of 55 units was built in 1967 as E 469.2. These had a revised body and cabs based on the E 669.1 and were the first Czechoslovak DC electric locomotive to have multiple controls. When some steam locomotives still had to be replaced a few years later, another 29 were built in 1971 as E 469.3. The three batches later became the classes 121, 122 and 123. Since after the division of Czechoslovakia no major railway lines in Slovakia were electrified with direct current, they all came to CD. According to their age, the 469.1 were the first to be either retired or sold to private railways by 2006. Most examples of the newer batches were retired between 2010 and 2020.

The E 669 is a series of six-axle freight locomotives designed by Škoda for operation under 3 kV DC. The first two prototypes were built in 1958 and 1959 as a development of the four-axle E 499.0. They had a top speed of 120 km/h, what turned out to be too high for heavy trains in the Slovak Tatra mountains. For this reason, the subsequent production models had a gear ratio for 90 km/h, what increased their starting tractive effort from 231 to 345 kN. The two prototypes were later also rebuilt to 90 km/h and used until 1996.

The first series was the E 669 .1 of which 150 were built in 1961 and 1962. The first 80 were additionally suited for 1.5 kV DC. The demand for more locomotives led to the E 669 .2, of which 168 were delivered between 1963 and 1965. Still more demand led to the E 669 .3 that was built 43 times in 1971. From the second batch of the E 669 .1 to the E 669 .3, all were nearly identical.

In 1988, the sub classes 0 to 3 became the new classes 180 to 183. After the breakup of Czechoslovakia, the sub classes were split among Czechia and Slovakia depending on their former area of operation. The 181 only came to the ČD, the 182 came to both the ČD and the ZSSK and the 183 only came to the ZSSK. Later they lost many services to four-axle locomotives like the class 163 which do less damage to the rails. From 2005, many came to private operators which will use them for some more years.

To test the optimum technology for electrification with 25,000 V and 50 Hz, the SNCF had four different types of electric locomotives built by different manufacturers. Testing took place on the line between Lille and Thionville, where heavy freight trains had to be moved over steep gradients. In addition to the BB 12000, BB 13000 and CC 14100, 20 CC 14000 were built with three-phase traction motors and a rotating converter. Although the electrical operation was a success in itself, the complexity of the CC 14000's technology meant it could not stand the test.

The CC 14100 was one of the electric locomotives ordered by the SNCF to find the right type of traction electrics for their new 25,000 V AC lines. In contrast to the CC 14000's complex three-phase system, it only had DC traction motors. But in this case, the 25,000 V current was first transformed to 3,000 V and fed into an electric motor that was connected to two generators. The power from these two generators was then used to feed the six traction motors. 

Like all its sisters, it had a crocodile-like appearance with a central cab and two long and low hoods. Due to this, these were all called “fer à repasser” (flatiron). These locomotives showed to be more reliable than the CC 14000. Despite their lower power, they managed to haul trains of 1,850 tonnes up a 1.1 percent incline and up to 3,500 tonnes on 0.5 percent, although at low speeds.

But since their area of operation was to haul heavy trains loaded with coal, ore, steel or scrap on winding secondary lines, these characteristics were well suited. In the seventies when transport volumes in this area sank, it was hard to find many other tasks due to the low top speed of 60 km/h. The first withdrawals took place in 1984, but it took until 1997 for all locomotives to disappear.

When the demand for high-speed freight locomotives increased in the 1960s, a further development of the E 50 was examined. The requirements stipulated on gradients of 0.5 percent to run express freight trains with 120 km/h and 1.000 tonnes or regular freight trains with 80 km/h and 2.000 tonnes. A change in the gear ratio of the E 50 failed because its traction motors, which were weaker than those of other standard electric locomotives, would not have been sufficient at higher speeds. However, a completely new development was ruled out due to time constraints. The solution now consisted of finding a compromise between the proven technology of standard locomotives and more modern assemblies.

Since the traction motors of the E 50 were not suitable for a larger increase in output, the traction motors from the E 10 and E 40 were further developed. With a total of six of these traction motors, an hourly output of 6,288 kW and a braking power of 6,600 kW over a short period could be achieved. Since the bogies and the electrical equipment of the E 50 were not suitable for this power, the technology of the class 103 was used. To facilitate maintenance, new design principles were used, which had also been used with the 103. The entire paneling of the engine room consisted of three large hoods, which, like the driver's cabs, could be removed as a whole. Compared to the previous class, the interior of the driver's cabs has been modernized in terms of comfort and ergonomics.

According to their design, the locomotives were used almost exclusively in front of fast or heavy freight trains. Nevertheless, they had the necessary equipment to be able to pull passenger trains when there was a shortage of locomotives. Only on the Franconian Forest ramp they were used in front of scheduled passenger trains, which has not been permitted since 2003 due to the lack of door blocking.

The heaviest freight trains used in Germany were ore trains, initially weighing 4,000 and later 6,000 tonnes, which ran from the North Sea ports to the steelworks inland and were each pulled by two class 151 locomotives. Since these loads were too great for the screw couplings common in Central Europe, 20 locomotives and a sufficient number of freight cars were equipped with central buffer couplings. When these services were discontinued in the 1990s, the locomotives were fitted with screw couplings again and assigned to other areas of application.

In contrast to the other standard locomotives, most of the locomotives remained painted in their original chrome oxide green color scheme into the 1990s. Their importance decreased with the increasing number of four-axle three-phase current locomotives for freight train use, since the DB wanted to quickly part with locomotives with three-axle bogies due to the increased wear on wheels and rails.

Since 2003, they have mostly only been used to push vehicles up ramps. At the same time, sales began to private companies, who will continue to use the locomotives for longer due to their performance and reliability. The largest customer was a consortium of Railpool and Toshiba, which signed the contract for the purchase of 100 of the 170 machines manufactured in 2017. At Deutsche Bahn, the locomotives are now being phased out when the maintenance deadlines expire.