Freight steam locomotive SO^М 17 1137

Unlike conventional steam locomotives, where steam is released into the atmosphere after performing useful work in the engine, designs with steam condensation featured special devices that cooled the exhaust steam and converted it into water, which could be reused in the boiler.

The development of conventional steam locomotives with steam condensation was continued by the German company Henschelz & Son after the construction of several steam turbine locomotives. The company successfully developed a steam condensation system that allowed for the recovery of up to 95% of the boiler water. The first such 1,000 mm gauge steam locomotive was built for Argentine railways in 1930.

The new locomotive underwent extensive testing under various climatic conditions for a considerable period: in winter on the Moscow–Kursk Railway, and in summer on the Central Asian Railway. The tests were conducted at different outside temperatures, using both oil and coal heating, and with trains of varying weights. Based on the results, expert opinions were divided: some saw great potential in the new locomotives, while others, particularly specialists from the Research Institute of Traction, considered them to be unpromising.

At the December Plenum of the Central Committee of the All-Union Communist Party (Bolsheviks) in 1935, People’s Commissar of Communication Routes L. M. Kaganovich declared: “In 1936, a new type of steam locomotive will be introduced to railway transport for the first time—one equipped with steam condensation. This locomotive will revolutionize the locomotive industry”. This announcement profoundly influenced the direction of domestic locomotive construction in the pre-war period.

At the beginning of 1936, two new SO17 locomotives—SO17-84 and SO17-85—built by the Kharkiv Locomotive Works, were delivered to the Kolomna Locomotive Works for conversion into condensation locomotives.

On 28th February 1936, the first domestically produced steam locomotive with steam condensation, SO17-85, undertook its trial run on the Golutvin–Ramenskoye section. On 8th March, the steam locomotive was presented at the Kiyv Station in Moscow to People’s Commissars L. M. Kaganovich and S. Ordzhonikidze, along with N. S. Khrushchev, Secretary of the Moscow Committee of the All-Union Communist Party (Bolsheviks). The steam locomotive’s innovative design was explained by Lebedyansky, the Kolomna Locomotive Works’s Designer, and Tomlenov, the Chief Engineer of the Central Steam Locomotive Directorate of the People’s Commissariat of Communication Routes. The condition of the steam locomotive, its initial tests, and meticulous exterior finishing earned the complete approval of the party leadership. In March, the conversion of the second locomotive was finalised.

Later in 1936, the Kharkiv and Bryansk Locomotive Works commenced mass production of SO19 steam locomotives—condensing steam locomotives of the SO class with an axial load from the driving wheelsets of approximately 19 t—concluding the production of SO17 steam locomotives. The primary supplier of P11 tender-condensers for the new locomotives was the Kolomna Machine-Building Plant.

The equipment of steam locomotives with steam condensation consisted of the following elements.

The condensing unit on the tender included a condenser, an exhaust-steam turbine, air fans, piping, and condensate tanks. The condenser itself consisted of a series of thin brass tubes fitted with external fins. As the exhaust steam travelled through these tubes, it transferred its heat to the air flowing over the tubes, cooling down and condensing into the water with a temperature of 80–90°C. To cool all the steam passing through the condenser within an hour, up to 650,000 m^³ of air was required. This quantity was supplied by three fans driven by a special exhaust steam turbine with a capacity of 170 hp.

The smoke exhaust system (centrifugal fan) replaced the blast pipe of an ordinary steam locomotive and was driven by an exhaust steam turbine with a capacity of about 70 hp.

Feed pumps and filters were used to deliver hot condensate to the boiler and to remove oil carried over with the steam from the steam locomotive engine.

The operation of the steam locomotive followed this sequence: steam that had completed its work in the steam engine entered an exhaust steam turbine, which powered the smoke exhauster. From there, the steam was directed via a special pipeline to the tender’s air fan turbine. After working there, the steam was routed to the condenser. Here the steam was converted back into water, which was collected in a dedicated condensation tank. From this tank, the water was pumped through filters, where it was purified, and then fed back into the boiler. The boiler heated the condensate, turning it back into steam, which worked in the steam engine once again.

The process of establishing serial production of condensing steam locomotives at steam locomotive manufacturing plants proved challenging. Delays in component deliveries, subpar assembly quality, and issues with low-quality smoke exhaust turbines frequently disrupted production schedules. The situation was further complicated by the plants having to independently develop and produce tender condensers.

To demonstrate the capabilities of the new locomotives to steam locomotive crews, a test run of the condensing steam locomotive SO17-635 (the first SO steam locomotives with steam condensation, built in Bryansk, had the old designation SO17) was conducted along the Moscow–Vladivostok–Moscow route from 9th December 1936 to 15th February 1937. Valentin Makarov, who delivered the Skovorodino–Moscow relay train hauled by the steam locomotive EL-689 in 1936 in 13 days without changing the steam locomotive or entering any depots, was appointed as Senior Steam Locomotive Driver.

As operational experience with the SO19 steam locomotives grew, design flaws in the tender-condenser began to surface. The tender, with an axial load of over 19 t, was initially equipped with wheelsets having a 900 mm diameter. This led to rapid wear and chipping of the binding bands. The issue was addressed by installing wheelsets with a diameter of 1,050 mm during repairs.

Another shortcoming of the tender was its limited fuel capacity of 14.5 t, which proved inadequate given the increased operational range of the condensing steam locomotives. An experimental four-axle condenser tender with an increased fuel capacity showed an unacceptable rise in axial loads. The only potential solution was the construction of five-axle or six-axle tenders, but this plan was never realised.

According to the transport development plan for the Third Five-Year Plan, approved in 1938 at the 18th Congress of the All-Union Communist Party (Bolsheviks), the fleet of SO condensing steam locomotives was to be expanded by 4,200 units by 1942. However, the reality turned out to be different: between 1936 and 1942, the Kharkiv, Bryansk, Voroshilovgrad, and Ulan-Ude plants built approximately 1,450 SO19 steam locomotives.

It’s important to note that the construction of such a large number of condensing steam locomotives was a case of technical voluntarism. While the use of condensing steam locomotives in the arid regions of Central Asia and in areas with water unsuitable for feeding steam locomotive boilers was justified, their widespread deployment proved to be an obvious mistake.

With the construction of a significant number of electric and diesel locomotives and the reduction of sections served by steam locomotives, the Ministry of Railways deemed the maintenance of a fleet of condensing steam locomotives impractical. Starting in the second half of the 1950s, the Orenburg, Zaporizhzhia, and Poltava steam locomotive repair plants began dismantling the condensation equipment from SO19 steam locomotives during medium or major repairs.

The SO^M17-1137 locomotive was originally built as a condensing steam locomotive, SO19-1137, by the Kharkiv Locomotive Works in 1938. Factory number: 5237.

After its construction, the locomotive was delivered to the Vyazma Depot of the Western Railway, where it served on the Vyazma–Mozhaysk, Vyazma–Smolensk, and Vyazma–Rzhev routes. In late 1940, it was transferred to the Kartaly Depot of the South Ural Railway. Then it operated at the Kazakhstan Depot of the Ryazan-Ural Railway, followed by a transfer to the Petropavlovsk Depot of the Omsk Railway.

Starting from December 1955, the steam locomotive operated at the Salsk Depot of the North Caucasus Railway. During a medium repair at the Poltava Locomotive Repair Plant in March 1958, the steam condensation equipment was removed, and a mechanical stoker was installed. The steam locomotive received the designation SO^М17-1137. After the repair, it was sent to the Kalinin Railway, where it operated at the Rzhev and Novosokolniki Depots.

In May 1963, the steam locomotive was placed in reserve at the Bologoye II reserve base. The total operational mileage was 1,011,734 km. On 29th September 1989, by order of TsTL-36, SO^M17-1137 was officially removed from the USSR Ministry of Railways’ inventory.

In 1990, it was transferred from the Bologoye II reserve base to the Leningrad-Finlyandsky Locomotive Depot for scrapping. While awaiting dismantling, it was placed at the Zelenogorsk reserve base. Shortly before that, the staff of the Central Museum of the Oktyabrskaya Railway successfully arranged the locomotive’s transfer to the museum.