The ALCO RSD-1 was a diesel-electric locomotive built by 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.[1]

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.
Type and origin
Power typeDiesel-electric
Build dateNovember 1942 – May 1946
Total produced150
 • UICCo'Co'
Gauge4 ft 8 12 in (1,435 mm) standard gauge
1,520 mm (4 ft 11 2732 in) – Russia
Length55 ft 5 34 in (16.91 m)
Width10 ft 0 in (3.05 m)
Height14 ft 5 in (4.39 m)
Loco weight247,500 lb (112,300 kg)
Fuel capacity1,000 US gal (830 imp gal; 3,800 L)
Prime moverALCO 539T
Engine typeStraight-6 Four-stroke diesel
Displacement9,572 cu in (157 L)
GeneratorDC generator
Traction motorsDC traction motors
Cylinder size12 12 in × 13 in (318 mm × 330 mm)
Loco brakeStraight air
Train brakesAir
Performance figures
Maximum speed65 mph (105 km/h)
Power output1,000 hp (750 kW)
Tractive effort40,425 lbf (179,820 N)
LocaleNorth America, Soviet Union, Iran
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.


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).

Soviet UnionEdit

Alco locosEdit

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).[1] 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.[1] 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-boatA20-41 and ДA20-50) and 68 were received.[1] 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[1] (the Soviet Union built only 51 diesel locomotives before the war, so it had not enough experience with designing).[2]

Soviet locosEdit

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

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.[3] They were almost identical, but locomotives after #TE1-20-122 had 1050 mm (41.34 inch), instead of 40 inch wheels (1016 mm).[3] The designation meant T - teplovoz (diesel engine), E - electric transmission, model 1, 20 ton axle load.[3] A production lasted from 1947 until 1950 and 300 were made (including 2 of TE5 class).[3] 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.[4] 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. [5] Only two (or five) TE5 were built, within TE1 series.[3]

US ArmyEdit

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

Original ownersEdit

Specification E1645Edit

Railroad Quantity Road Numbers Notes
United States Army

Persian Gulf Command, Iran

United States Army

Specification E1646Edit

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

Specification E1647Edit

Railroad Quantity Road Numbers Notes
Ferrocarriles Nacionales de México


  1. ^ a b c d e f Rakov (1995), p. 371-374.
  2. ^ Rakov (1995), p. 356.
  3. ^ a b c d e Rakov (1995), p. 375-377.
  4. ^ Rakov (1995), p. 379-380.
  5. ^ Westwood, J.N. (1963). Soviet Railways Today. London: Ian Allan. p. 71.
  6. ^
  • Rakov, Vitaliy (1995). Lokomotivy otechestvennyh zheleznyh dorog 1845-1955 [Locomotives of domestic railways 1845-1955] (in Russian). Moscow. ISBN 5-277-00821-7.

External linksEdit

Another RSD-1 roster with build dates