South African Class ME 2-6-6-2

The South African Railways Class ME 2-6-6-2 was a single experimental Mallet articulated steam locomotive, ordered from the North British Locomotive Company in 1911 by the Central South African Railways for test work on branch lines laid with light 45 pounds per yard rail. It was delivered in January 1912, by which time the Central South African Railways had become part of the South African Railways, so it was classified as the sole Class ME and numbered 1618. Unlike the compound Mallets of the period it was a simple expansion engine with four high-pressure cylinders, outside the plate frames, worked by Walschaerts valve gear, with a Belpaire firebox, a Schmidt superheater and a boiler pressure of 170 pounds per square inch. Either engine unit could be cut out while running light. Although bought as an experiment it proved successful and remained in service for 25 years, working its last years on the line from Nelspruit to Sabie before it was withdrawn and scrapped in 1937.