The class ME No. 1618 was a single 2-6-6-2 Mallet built by North British in 1912. It was an experiment to get a powerful locomotive for branch lines with light rails. It received a superheater and had a relatively low boiler pressure, but was the SAR's only Mallet with simple expansion. It was actually successful in service and with an axle load of 9 tons 18 cwt, it could be used virtually anywhere. But 1618 remained the only one and later Mallets were compounds again. In its last years, it was used on the Eastern Transvaal Lowveld and was scrapped in 1937.