Rhodesia Railways classes 20 and 20A

The most powerful locomotives to ever operate for the Rhodesia Railways were the Garratts of the 20^th class. They were of the wheel arrangement 4-8-2+2-8-4T (Double Mountain) and weighed more than 220 tons. Features of these locomotives were bar frames and thermic syphons. They were also the only locomotives of the Rhodesia Railways which had a mechanical stoker.

After 21 locomotives of the original 20^th class, the next 40 were designated class 20A. Apart from being around 10.000 pounds heavier, the inner trailing axles had bigger wheels. Both batches suffered from teething troubles, which included cracks in the frames and fireboxes. On 1 in 64 inclines (1.55 percent), they could haul 1.250 tons. On flatter lines, they were rated for 1.500 to 1.700 tons at a speed of 45 mph (72 km/h).

In 1964, they were split among Zambia and Rhodesia. In Zambia, they were withdrawn around 1970. Four were briefly operated again in 1979 and 1980 due to an oil shortage. In Rhodesia and the later Zimbabwe, they were still needed for a longer time. So they were rebuilt between 1980 and 1983 and equipped with roller bearings. Withdrawals were completed in 1994. Eight are still existing.