DC Freight Electric Locomotive S_S^M 14

Work on the electrification of domestic railways in the USSR began in the late 1920s and early 1930s. One of the first sections to be converted to electric traction was the Khashuri–Zestaponi section of the South Caucasus Railway in 1932. This line passed through mountainous terrain via the Surami Pass, featuring very steep gradients of up to 29‰ and curves with a radius of up to 150 m. The use of electric traction was particularly effective in these challenging conditions.

In order to quickly adopt electric traction, a decision was made to adopt foreign experience. As a result, orders were placed with foreign companies for the production of two batches of DC electric locomotives, to eventually master the production of similar locomotives domestically. Between 1932 and 1934, the USSR received electric locomotives of the class S series (eight units built by the American company General Electric) and the class SI (six units built by the Italian company Brown Boveri). These locomotives were tested and operated at the Surami Pass.

Due to the fact that the American-made class S electric locomotives were deemed more suitable for domestic conditions, they were used as prototypes for the production of similar locomotives in the USSR.

Based on technical documentation received from General Electric, the USSR began producing DC electric locomotives, which received the SS designation. Initially, they were designated as S_S 11, where the number indicated the axial load in tonnes. The letter “S” in the names of all the above-mentioned electric locomotives stood for “Surami”, and the designation SS specified them as “Surami Soviet”.

These locomotives that feature specific design characteristics such as regenerative braking and unique undercarriage features, belong to the family of electric locomotives known as the Surami type.

The S_S was a single-section, six-axle freight electric locomotive designed for freight traffic. Two three-axle trucks with bar-type frames were connected to one another via a special articulated connector. The body of the electric locomotive had a frame structure with platforms on each side, allowing entry into the control cab.

The traction electric motors, DPE-340, with a continuous rating of 300 kW featured a support-axle suspension. The traction gearbox had a gear ratio of 89 ÷ 20 = 4.45. The power electrical circuit provided three types of traction motor connections: series, series-parallel, and parallel. In the future, this design would become a staple of Soviet freight DC electric locomotives

Most of the S_S< series electric locomotives were delivered directly to the Chusovskaya Depot of the Perm Railway, where they were initially used on the Chusovskaya–Kizel line. Later, they were deployed on other electrified sections of the railway, which eventually became part of the Sverdlovsk Railway.

In the 1950s, some of these locomotives underwent modernisation of their electrical equipment, incorporating machines and devices used on the VL22^М electric locomotives. After this upgrade, they were re-designated as S_S^М. The operation of these locomotives ended in 1968–1974.

The S_S11 14 electric locomotive (S_S^М 14 after modernisation) was built in 1933 both at the Kolomna Locomotive Works and Dynamo Plant. By the end of its service life, it had one truck from the S electric locomotive built by General Electric and the other from the VL19 electric locomotive. In the 1980s, it was transferred from the Perm-2 Depot of the Sverdlovsk Railway to the collection of the Central Museum of Railway Transport.