The Vladikavkaz Railway was convinced that an express locomotive needed a leading bogie. Thus, instead of the 2-6-0 wheel arrangement, the 4-6-0 wheel arrangement was chosen and the series A was designed with it. These were two-cylinder compound machines, of which six were manufactured in Kolomna in 1892. The production machines were slightly heavier with a larger low-pressure cylinder. Their production started in 1894 also at German manufacturers. Some of the locomotives were later oil-fired.

The railway administrations of the Tsarist Empire combined eight-coupled freight locomotives under the letter О, which made it to a number of more than 9,000 in different versions. The series went back to a type from Maschinenfabrik Esslingen, which had been supplied to several railway administrations from 1878 onwards. In order to follow the trend of the time, the Vladikavkaz railway had two-cylinder compound locomotives based on this type manufactured in Kolomna in 1890, which marked the beginning of the О series.

O_в No. 324 in August 2015 at the Podmoskovnaya depot in Moscow

Andreykor

From 1893 a unified standard type was manufactured, which had a wheel diameter of only 1,150 mm and cylinders with a diameter of initially 500 and 710 mm with a stroke of 650 mm. After 129 examples were produced, the diameter of the low-pressure cylinder was increased to 730 mm. A total of 1,373 examples of the standard type from 1893 were manufactured by 1899, which were also supplied from Germany and Austria due to the limited capacities of the Russian factories.

Armoured locomotive O_? No. 5067 in the Central Museum of the Russian Armed Forces

Valery Ded

In 1897 a new standard type appeared, of which a total of 3,172 were built by eight Russian factories by 1903. This variant, designated О^д, now had a driver diameter of 1,200 mm and a boiler pressure increased from 11 to 11.5 bar.

After two prototypes were completed in 1899 with a Heusinger type valve gear instead of the problematic Joy valve gear, a total of 4,178 examples were built between 1901 and 1907, which also had a Heusinger valve gear. The diameter of the cylinders had been increased to 510 and 740 mm. The two types were designated О^в and О^k and were alternatively known as the 1901 standard type and the 1904 standard type. Between 1908 and 1915 another 190 examples of the О^в were made.

When superheated steam became established in locomotive construction, a few locomotives with superheaters and simple expansion were built between 1908 and 1915. These were given the designation О^п and soon other examples of the earlier series were rebuilt in the same way. After the October Revolution, another 72 pieces were made between 1925 and 1928. Later, some locomotives received boilers with a pressure of 14 bar during conversions. After the introduction of more powerful freight locomotives from the 1930s, they were increasingly used for shunting. The last operations on the route took place in 1964 on a branch line of the Trans-Baikal.

In order to speed up freight trains, the series Р (R) was developed with a 2-8-0 wheel arrangement to replace the existing 0-8-0 locomotives. The special feature was the tandem compound engine, in which the high and low pressure cylinders were located one behind the other on both sides. This saved the need for a cranked axle, but the special arrangement of the cylinders meant that there was a lot of maintenance work. Since the speed was soon no longer sufficient on flat land lines and more powerful locomotives were available on mountain lines, the locomotives were only used on industrial railways from around 1940.

Shortly after the turn of the century, the Central Siberian Railway required powerful passenger locomotives for its winding mountain routes with light rails. In order to ensure sufficient mobility and to comply with the axle loads, the B^K was created in the Mallet design with a 2-4-4-0 wheel arrangement. Kolomna initially made five locomotives with compound engines and four with four equal-sized cylinders, which had a slightly larger boiler with a lower pressure.

103 more followed until 1909, all of which had compound engines. They were soon renamed to І by the Russian State Railways. They did not reach a larger number because they had a higher consumption and more complex maintenance than locomotives with a one-piece frame. Nevertheless, they remained in use for a long time, so that the last machine was not retired until 1954.

The Russian railways used the letter Б (B) to group express locomotives with a 4-6-0 wheel arrangement, i.e. in Russian notation 2-3-0. Between 1896 and 1903, locomotives with four-cylinder compound engines were manufactured for several railway administrations. The driver's cab was closed off to the rear by the tender. They had cylinder diameters of 370 and 580 mm with a stroke of 650 mm and a coupling wheel diameter of 1,730 mm. In Russian conditions, especially in the harsh winters, maintenance of the four-cylinder engine proved too complicated. They also proved to be too fuel-intensive on long, straight stretches. As a result, many locomotives were converted to simple engines from around 1910 and fitted with superheaters. The new cylinders had a relatively long stroke of 700 mm with a diameter of only 550 mm.

In 1907, the Moscow-Kyiv-Voronesh Railway ordered three locomotives from the Bryansk works, which already equaled the two-cylinder superheated version ex works. From 1909 other railways ordered more examples of this design, so that the number increased to 252, of which 99 were built in Luhansk. The locomotives reached up to 125 km/h in test drives and were certified for 105 km/h. This was later increased to 115 km/h. With the introduction of more modern locomotives, the Б series locomotives were later moved to the eastern, more sparsely populated areas and finally retired in the 1950s.

The letter Э (E) designated a family of tender locomotives with a 0-10-0 wheel arrangement on the Russian and Soviet railways. With a number of more than 10,000 and a production period of 45 years, it is the most-built steam locomotive of all time. Not only factories in Russia and the Soviet Union were involved, but also factories in other European countries.

The design came from Wacław Łopuszyński from the Vladikavkaz Railway. Here, for the first time, five coupled axles were necessary because the axle loads were limited and a sufficiently strong freight locomotive was required for the increasing train weights. The Gölsdorf system was used here, in which some of the axles could be moved sideways. Other requirements included a Belpaire firebox and a Schmidt-type superheater. 

The first 15 locomotives were delivered from Lugansk in 1912 only to the Vladikavkaz railway. Other railway administrations soon followed and from 1915 production was also handed over to other works. The cylinder diameter increased from initially 600 to 630 to 650 mm. A total of 1,528 of the basic variant had been manufactured by 1925.

Since industrial capacity had declined significantly after the October Revolution and a large number of freight locomotives were needed for the reconstruction, manufacturers were now sought in the West. They first turned to NoHAB in Sweden, where 1,000 copies of the Э^ш were to be manufactured. The letter ш (Sch) stood for “Sweden”. The first 18 locomotives were delivered by rail in a cumbersome and time-consuming process, since the track gauges differed from country to country. The rest was then transported by ship.

Although many subcontractors were involved in the production, the ordered 1,000 locomotives could not be delivered. Now a large number of German manufacturers were also taken on board, so that ultimately between 1921 and 1924 500 were manufactured in Sweden and 700 in Germany. The German locomotives were designated Э^г, with the г (G) standing for “Germany”.

Production capacities were soon available again in the Soviet Union, but the industry was not yet ready for a complete redesign. Thus the Э^У (E^U) was developed, which achieved an additional performance of 15 percent thanks to a newly developed superheater. 2,535 of these were made between 1926 and 1931.

This was followed by the Э^М (E^M), which was primarily adapted to the increased transport volumes with a higher boiler pressure. Since weight had been saved in some places by welding and the omission of the feed dome, the axle loads were distributed unevenly. Nevertheless, a total of 2,325 of this variant were made between 1931 and 1935.

The problems with the Э^М were solved with the Э^Р, which had a longer firebox and again a feed dome. In addition, it achieved an increase in output of ten to 15 percent with an eight percent increase in efficiency. During World War II some came to Finland where they were used as Tr2. Since the Soviet industry was no longer able to produce sufficient quantities of freight locomotives itself after the end of the war and no new design was possible, further Э^Р were built in their own country and also in other countries of the Warsaw pact. When production ended in 1957, a total of 3,044 Э^Р had been built.

Due to its large number, the Э was distributed throughout the country. It was not only used in front of freight trains, but also in front of passenger trains. Over the years it has been used for various trials, such as thermic syphons, improvements to the firebox or pulverized coal firing. Although production continued into the 1950s, many of the older variants were already being moved to shunting service or handed over to industry during this period. In the sixties the decommissioning started in larger numbers.

After entering the First World War, the Russian Empire urgently needed heavy freight locomotives in order to be able to transport war supplies over mountainous sections. The aim was to replace the outdated Series Ф (F) Fairlie locomotives. It was planned to order a single-frame locomotive with five coupled axles. Since there was no way at that time to produce large numbers in Russia in a short time, the locomotives were ordered in North America.

20 years earlier Baldwin had delivered two four-cylinder compound locomotives in 2-10-0 wheel arrangement to the Transcaucasian Railway, which were known as the Д_K (D-K) series. Now there was the opportunity to purchase 400 locomotives from North American manufacturers in a short time. 250 came from Baldwin, 100 from ALCO and 50 from the CLC. The designs originated in Russia and were adapted to imperial dimensions in America for ease of production. The grate area was set at six square meters in order to be able to burn coal of a lower quality. The first 400 locomotives from the three manufacturers were named E^Ф for Philadelphia (Baldwin), E^c for Schenectady (ALCO) or E^k for Kingston (CLC).

A further batch with minor improvements was designated E^Л in honor of Lomonosov. When the USA entered the war, it was possible to produce larger quantities as war aid. In total, depending on the source, about 881 pieces were delivered to the Russian Empire, some of which were lost on the long sea route from New York to the Far East. About 200 pieces were distributed to customers in the USA because they could not be delivered after the October 1917 revolution.

Although the engines were a successful design, they initially showed some deficits in operation. These were in part due to corrosion during sea transport, which led to problems with the firebox and other assemblies. Likewise, people in Russia were not yet familiar with the maintenance of the bar frames that are common in North America and therefore initially had to contend with high failure rates. Gradually, however, one could become friends with the machines and found ways to maintain them sufficiently. Thus, later larger numbers of the series Е of the Soviet railways were built.