To meet the increasing weight of fast passenger trains on the Western and Midland Systems, the 6th Class 4-6-0 passenger steam locomotive was conceived and designed at the Salt River works of the Cape Government Railways (CGR) at the same time as the 7th Class, both according to the specifications of Michael Stephens, then Chief Locomotive Superintendent of the CGR, and under the supervision of H.M. Beatty, then Locomotive Superintendent of the Western System.
Whereas the 7th Class was conceived primarily as a goods locomotive, the 6th Class was intended to be its fast passenger service counterpart.

The 6th Class introduced the Type YB tender, a three-axle tender with a coal capacity of 5 long tons 10 hundredweight (5.6 tonnes) and a water capacity of 2,370 imperial gallons (10,800 litres).
The engines and tenders were built by Dübs and Company and were delivered in 1893 and 1894, numbered in the ranges from 139 to 160 for the Western System and 353 to 370 for the Midland System.
To meet the increasing weight of fast passenger trains on the Western and Midland Systems, the 6th Class 4-6-0 passenger steam locomotive was conceived and designed at the Salt River works of the Cape Government Railways (CGR) at the same time as the 7th Class, both according to the specifications of Michael Stephens, then Chief Locomotive Superintendent of the CGR, and under the supervision of H.M. Beatty, then Locomotive Superintendent of the Western System. Whereas the 7th Class was conceived primarily as a goods locomotive, the 6th Class was intended to be its fast passenger service counterpart.
The 6th Class introduced the Type YB tender, a three-axle tender with a coal capacity of 5 long tons 10 hundredweight (5.6 tonnes) and a water capacity of 2,370 imperial gallons (10,800 litres). The engines and tenders were built by Dübs and Company and were delivered in 1893 and 1894, numbered in the ranges from 139 to 160 for the Western System and 353 to 370 for the Midland System.
South African Class 6 4-6-0