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 . 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 )
Potsdam Conference
Potsdam Conference
ALCO RSD-1