on excursion trains, operated by private steam enthusiast groups in Cape Town and in Gauteng. Soviet Union From the mid-1930s until their replacement by diesel locomotives, the 2-8-4 (1’D2’-h2) wheel arrangement was relatively common in the former Soviet Union. When built, these locomotives were designated Class IS, for Josif Stalin. The Class IS locomotive was a passenger derivative of the Class FD 1’E1’-h2 (2-10-2) freight locomotive and had many parts in common with the Class FD. The Soviet 2-8-4 was the most numerous single Berkshire class built in the world. Kolomna Locomotive Works built the first four locomotives. In 1935, production was transferred to the enlarged and modernised former Luhansk Works which was renamed Voroshilovgrad Locomotive Works. A total of 649 locomotives of the two variants, Class IS20 and Class IS21 (later Class FDp), were built between 1932 and 1942. After Germany attacked the Soviet Union on 22 June 1941, the Russians evacuated all semi-completed class IS21 locomotives from Voroshilovgrad. The Ulan-Ude Locomotive Works completed the last eleven in 1941 and 1942. Despite their moderate size compared to American and Canadian-built 2-8-4s, the Soviet 2-8-4 was a good example of a Berkshire type designed for heavy express and passenger train service. It had a grate, boiler pressure, boiler heating surface of which was superheated, and only 20 to 21 tons maximum axle load. Their diameter coupled wheels and cylinders of bore and stroke, with a total weight of 133 tonnes of which 80.7 tonnes were adhesive weight, enabled the locomotives to easily reach the maximum permitted speed of with 700 to 800 tons behind the tender. The usual maximum speed was about , with an occasional need of . They were used as express passenger locomotives on mainlines which had type Ia rails of . They were later reclassified as Class FDp (FD passenger). One locomotive, no. IS20-16, was streamlined and achieved a speed of during test runs in 1937. Another, no. IS20-241, was displayed at the Paris World Exhibition in 1937, where it demonstrated the Soviet Union's locomotive production. The first four were initially allocated to the October Railway and ran between Moscow and Leningrad, hauling heavy night passenger trains. Later, when the line was upgraded with heavier rails, they were transferred to the Moscow-Kursk-Kharkov-Sinelnikovo line. When more class IS locomotives began to roll out from the Voroshilovgrad production lines, they were used on the upgraded Moscow-Smolensk-Minsk, Moscow to