which were still in active service in 1952. However, these locomotives were retired after the MRR turned to upgrading its fleet to diesel locomotives in 1956. Not a single unit was preserved. Poland Twenty-five OKz32 2-10-2 tank locomotives were built by H. Cegielski – Poznań and delivered to PKP between 1934 and 1936. They were used mainly to work passenger trains between Kraków and Zakopane, a difficult railway line, steep in places, with many sharp curves, and requiring three direction changes. One has been preserved in working condition. Romania Romania designed its 151.000 Class as freight locomotives to serve on the Căile Ferate Române (CFR). These locomotives used a straightforward two-cylinder engine with diameter coupled wheels and a total weight in working order of . The heating surface of the boiler was , of which were superheated, while the grate area was . At a tractive effort of , they were the most powerful steam locomotives built in Romania. Two of these locomotives were built by the Malaxa Works in 1939 and 1941, numbered 151.001 and 151.002. Number 151.002 was preserved. South Africa On , this wheel arrangement was first used by the South African Railways (SAR) in 1927. Two Class 18 steam locomotives, the most powerful non-articulated locomotives to see service on the SAR, were introduced on the line between Witbank and Germiston in an attempt to ease problems that were being experienced with increasingly heavy coal trains. It was designed by Colonel F.R. Collins DSO, Chief Mechanical Engineer of the SAR from 1922 to 1929, and built by Henschel and Son in Germany. They were three-cylinder locomotives, with the two outer cylinders using Walschaerts valve gear and the inner cylinder using Gresley conjugated valve gear, actuated by the motions of the outer cylinders. One more locomotive, the Class 20, was designed for branch line work on light rail by A.G. Watson, Chief Mechanical Engineer from 1929 to 1936. Only one locomotive was built by the SAR at its Pretoria Mechanical Shops at Salvokop in 1935. In 1950, this sole Class 20 locomotive was modified to an experimental condensing locomotive, equipped with a condensing tender that was ordered from Henschel in Germany in 1948. Beginning in 1951, tests with the condensing Class 20 were conducted in the Eastern Transvaal and the Karoo. The positive results of the condensing trials proved the viability of condensing locomotives in South Africa and