The Central South African Railways Rack 4-6-4T of 1905 is a South African steam locomotive from the pre-Union era in the Transvaal.In 1905 the Central South African Railways placed two four-cylinder rack tank locomotives with a 4-6-4 Hudson type wheel arrangement in service on the section between Waterval Onder and Waterval Boven, but the locomotives were underpowered and proved to be failures in rack service, with the result that their rack mechanisms were removed in 1906 to convert them to ordinary two-cylinder tank locomotives.