Former US Army ALCO RSD-1, now owned by the Tennessee Valley Railroad Museum.

Donated from the Eglin Air Force Base Railroad when that operation was abandoned.

(The copyright holder of this file, Harvey Henkelmann, allows anyone to use it for any purpose, provided that the

copyright holder is properly attributed. Redistribution, derivative work, commercial use, and all other use is permitted, via Wikipedia Commons)



The ALCO RSD-1 was a diesel-electric locomotive built by the American Locomotive Company (ALCO). This model was a road switcher type rated at 1,000 horsepower (750 kW) and rode on three-axle trucks, having a C-C wheel arrangement. It was often used in much the same manner as its four-axle counterpart, the ALCO RS-1, though the six-motor design allowed better tractive effort at lower speeds, as well as a lower weight-per-axle. It was developed to meet the need to supply the Soviet Union over the Trans-Iranian Railway starting in mid 1943. On the other hand, due to the traction generator and appurtenant control apparatus being sized for four axles and yet having two additional powered axles, it had poorer performance at higher speeds.



There were three different specifications issued that covered the RSD-1 model; E1645 and E1646 were for wartime production for the US Army, while E1647 was a post-war order for the Mexican National Railways (Ferrocarriles Nacionales de México).


Former Soviet Railways Да20-09 (DA20-09) on exhibit at the railway museum in former Varshavsky terminal, Saint Petersburg, Russia.

Originally built by ALCO as a model RSD-1 in 1944 and exported to the USSR.

(Sergey Nemanov (Photocity), CC BY-SA 2.5 <>, via Wikimedia Commons)


Soviet Union

Alco locos
Seventy of the RSD-1s were shipped overseas to the Soviet Union in early 1945 during World War II, as part of the Allied war effort. They were classed there as the Soviet Railways ДA20 (DA20) class, also known just as ДА after 1947 (D for Diesel, A for Alco and 20 for axle load in tons). They were used in ordinary line service rather than shunting, especially in southern parts of the Soviet Union (Turkmenistan), where water for steam locomotives was scarce. These locomotives were also used on the Trans-Iranian Railway. The Soviets subsequently kept many of the RSD-1s after the war, adopting the design to form the basis of their own line of diesel locomotives TE1, TEM1 and TEM2. Two RSD-1s were sunk en route to the Soviet Union when the ship they were on was torpedoed by a German U-boat (ДA20-41 and ДA20-50) and 68 were received. They entered service from March 1945, and some were still in service in the 1980s.[1] The DA20-27 hauled Stalin's train to Potsdam Conference, and its positive evaluation was among reasons to copy the design (the Soviet Union built only 51 diesel locomotives before the war, so it had not enough experience with designing).


Diesel locomotive TE5-20-032 in the Railway Museum in Saint Petersburg, Russia.

(Sergey Nemanov, CC BY-SA 2.5 <>, via Wikimedia Commons)


Soviet locos

The Soviet-built TE1 (ТЭ1), initially designed TE1-20, was a reverse engineered copy of the Alco product, adapted to metric system and Soviet norms. They were almost identical, but locomotives after No. TE1-20-122 had 1050 mm (41.34 inch), instead of 40 inch wheels (1016 mm). The designation meant T - teplovoz (diesel engine), E - electric transmission, model 1, 20 ton axle load. A production lasted from 1947 until 1950 and 300 were made (including 2 of TE5 class). The TE2 (ТЭ2) utilized engine and electric components of TE1, but was as a twin-unit version, with a wagon-type body and utilized two-axle bogies. The TE5 (ТЭ5) was a cold climate version of the TE1. The cab was extended for most of the locomotive to provide covered access to the engine and a boiler was added to keep the cab warm when the engine was not running. Only two (or five) TE5 were built, within TE1 series.


RSD-1 being delivered to the US Army Transportation Museum at Fort Eustis, seen in 2011.

(by Lyna Tucker 633d Air Base Wing Public Affairs, Public domain, via Wikimedia Commons)


US Army

The first 13 RS-1s were requisitioned by the US Army, returned to ALCO and rebuilt to RSD-1s Nos. 8000-8012 for use on the Trans Iranian Railroad. This effort was to supply the Soviet Union.


Original owners

Specification E1645

Railroad Quantity Road numbers Notes
United States Army 13 8000–8012 Persian Gulf Command, Iran
United States Army 44 8013–8056 8040 and 8045 rebuilt for Alaska Railroad as RF1 in October 1947, renumbered 1050A and 1050B

Specification E1646

Railroad Quantity Road numbers Notes
United States Army 30 8600–8629 to Soviet Railways Да20-1 to Да20-30
United States Army 11 8630–8640 lost in U-boat attack
United States Army 8 8641–8648 to Soviet Railways Да20-31 to Да20-38
United States Army 1 8649 lost in U-boat attack
United States Army 30 8650-8679
United States Army 20 8680–8699 to Soviet Railways Да20-39 to Да20-58

Specification E1647

Railroad Quantity Road numbers Notes
Ferrocarriles Nacionales de México 6 5700–5705


Type and origin
Power type: Diesel-electric
Model: RSD-1
Build date: November 1942 – May 1946
Total produced: 150
Configuration: AAR C-C; UIC Co'Co'
Gauge: 4 ft 8+1⁄2 in (1,435 mm) standard gauge; 1,520 mm (4 ft 11+27⁄32 in) – Russia
Length: 55 ft 5+3⁄4 in (16.91 m)
Width: 10 ft 0 in (3.05 m)
Height: 14 ft 5 in (4.39 m)
Locomotive weight: 247,500 lb (112,300 kg)
Fuel capacity: 1,000 US gal (830 imp gal; 3,800 L)
Prime mover: Alco 244T, 539T
Engine type: Straight-6 Four-stroke diesel
Aspiration: Turbocharger
Displacement: 9,572 cu in (157 L)
Generator: DC generator
Traction motors: DC traction motors
Cylinders: 6
Cylinder size: 12+1⁄2 in × 13 in (318 mm × 330 mm)
Transmission: Electric
Locomotive brake: Straight air
Train brakes: Air
Performance figures
Maximum speed: 65 mph (105 km/h)
Power output: 1,000 hp (750 kW)
Tractive effort: 40,425 lbf (179,820 N)
Locale: North America, Soviet Union, Iran, North Korea