4-6-4 Steam Locomotives in Russia

Class 2-3-2V (Locobase 737)

Data from 2-3-2B [V]" in Wikipedia at [], last accessed 21 September 2023.

Similar to Class V engines, but with much bigger drivers. 6998 developed 3,400 hp during a test in which it pulled a 900-ton train up a 0.6% grade that it entered at 110 kph (68.3 mph) and topped out at 76 kph (47.2 mph).

Wikipedia places this single locomotive in the context of Soviet State Railways wishing to increase the power and maximum speed of its express locomotives. The 1932 design of IS 2-8-4s (Locobase 4352) offered a good level of power, but was limited in its speed. So Lvov, the Voroshilovgrad Works's design engineer developed a locomotive that borrowed from existing engines like the FD (Locobase 727) and IS, but explored the value of taller drivers and streamlining.

Collaboration with what Google translates as the "Moscow Aviation Institute's" wind tunnel resulted in the profile visible in photographs.The design's streamlining thrust a large hemispherical nose forward of the front buffers. Its obtrusiveness wasn't helped by the use of a large, silver star surrounding the single, centered headlight. Much of the rest of the sheathing fell in line with streamline designs in several other countries. A smooth glacis under the nose hid cylinder heads and air brake pumps. A valence below a high running board that continued back to below the cab exposed all of the running gear.

Lvov's economy in design centered on using "most of the elements of the steam boiler [tubes, firebox, and other fittings], cylinders, rear bogie frame, axle liners and wedges, as well as much more." Thus, if the 2-3-2 B operated from depots that also ran FDs or IS locomotives, most repairs would use already existing stores. Innovation included high-strength steel in the frame, much of which was welded. Steel alloys in the motion, all axles turned in roller bearings, and drivers eschewed spokes by adopting discs similar to those of Boxpok or Baldwin.

Once in service in June 1938, limited tests such as the one described above showed promise at a cost of a 15% increase in fuel consumption "per unit of work." But the 6998's potential could not be fully sampled "and its thermal performance were never fully studied." After the end of the Great Patriotic War in 1945, the SDZ removed the shroud and limited speeds to 70 kph (43.5 mph). Obviously, some engineers wondered just what its upper speed limit might be, so the railway coupled a special train to the 6998 in 1957 and set a Soviet steam traction record of 175 kph (108.7 mph).

6998 was retired in 1963 and scrapped.

Class Soviet Railways series 2-3-2? (Locobase 736)

Data from "2-3-2K - Wikipedia" at [], last accessed 18 May 2026 (Google translation) ; and "Soviet Railways series 2-3-2K", Loco-info.com at [], last accessed 18 May 2026.

First two of a proposed class of ten streamliners intended to work the Moscow-Leningrad line's Krasnaya Strela (Red Arrow). Wikipedia explains that Soviet aspirations for even higher passenger-train speeds prompted the Soviet State railways to undertake aerodynamic research at NIIZhT, in collaboration with the Moscow Aviation Institute.

Kolomna tested a 2-3-1 (4-6-2) that offered 5 sq m (53.81 sq ft), and two with grate areas of 6 sq m (64.58 sq ft) rolling on 1-3-2 (2-6-4) and 2-3-2 (4-6-4) wheel arrangements and turning 1,850 mm (72.8") drivers.

After choosing the larger grate and four-wheel truck under the firebox, Kolomna delivered design IS20-16 (road #1) on 7 November 1937 which reached 155 kph (96.3 mph). A 29 June 1938 test attained 171 kph (106 mph) hauling four coaches on 14 axles.

Construction details suggests several goals: higher speed, robust components, and safety. Speed would require both streamlining and reduced mechanical friction. All axles turned in roller bearings, driving axle boxes and the valve gear links used a solid lubricant (to stand up to the heat and forces generated at such high speeds), and weight reduction through welding, and simplified boiler design without a combustion chamber. Brakes on all locomotive axles provided an additional safety measure

No. 1 hit 106 mph (171 kph) in a test run on 29 June 1938. Wikipedia reports that Railway Transport Research Institute tests established that (Google translates): "at a speed of 149 km/h, Locomotive No. 1 generated an output of 3,070 horsepower, while its steam consumption stood at a mere 6.7 kg (14.8 lb) per hp hour)-a figure lower than that of any steam locomotive built previously." RTRI also claimed the L40 superheater outperformed an Elesco-type superheater.

When the 1 (and 2) began service on the October Railway timetable, the running times reduced their maximum allowable speeds so much that they actually used 12% more fuel that a standard Su-series engine. (Wikipedia's English-language article also notes that uniquely replacement parts

When put on the Red Arrow service, however, they took only 8 hours to make the round trip between Leningrad and Moscow. Over the next two years (1938-1940), each of the two super-express engines traveled 170,000 km (105,590 miles).

The Russian participation in the partition of Poland and war with Finland in 1939 annulled plans for ten similar express engines.

After the 1941-1945 war ended, a completely changed railway landscape. As a result, the two locomotive lost their streamlining and trailing-truck brakes. And the speed limit dropped to 70 kph (

#2 had different superheater and boiler tubes; it operated until 1957-1958.