The original Class 3 was a D.A. Hendrie design [the Superintendant of the then Natal Government Railway (NGR)] and 30 were built by North British Locomotive Co. between 1909 and 1910 for use for coal traffic on the upper Natal Main Line. They were named locally as "Hendrie "D". These Class 3's used saturated steam and "D" valves.

After a visit to America in 1909 to the American Locomotive Company a single "experimental" Class 3A was built [nicknamed "Maude Allen" and known locally a the "American D"] with bar frames and Walscaert's valve gear. The main significance of this locomotive was that it used superheated steam technology and was the first locomotive of its kind to use this technology in Natal. She became a Class 3A and was eventually withdrawn from service in 1935.

To accomodate the revised cylinder configuration it was necessary to lift the running boards which resulted in gentle sweeps at either end to the buffer beams. This became the "Hendrie" hallmark.

When more Class 3 locomotives were required D.A. Hendrie decided use the Class 3A design and to superheat them and fit steam valves.

10 of these new design locomotives were then built by North British Locomotive Co. in 1912 and became the 3B. When re-boilered with the standard No.2 boiler they became Class 3BR.

These were used extensively on the upper section of the Natal Main Line and they were later used in the Eastern Transvaal [now Mpumalanga] and the Eastern Cape until sent to Cape Town for shunting where they too were withdrawn from service in 1974.