Between 1913 and 1915, the South African Railways placed 45 Class 14 steam locomotives with a 4-8-2 Mountain type wheel arrangement in service in Natal.

Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR), it was believed that small differences in wheel diameter had disproportionate effects on performance.

An innovation was the arrangement of the laminated side control springs in combination with two point swing links, which would be part of all Hendrie's subsequent designs.

[1] The engines were fitted with Pyle National turbo-generators and headlamps, with the generator attached to the top of the smokebox, ahead of the chimney.

[1] During the 1930s, many serving locomotives were reboilered with a standard boiler type designed by then CME A.G. Watson as part of his standardisation policy.

Only slight modifications were found necessary to take the new boilers, such as a cast packer under the smokebox saddle and a widening of the running board below the cab.

The flangeless leading coupled wheels were flanged and Type MR tenders were attached to the reboilered engines.