page_title: 4-6-2
section_title: Cape Government Railways
hierarchical_section_title: 4-6-2 / Usage / South Africa / Cape gauge / Cape Government Railways
caption_attribution_description: English: South African Railways Class 5A 721 (4-6-2), ex Cape Government Railways “Karoo” Class 903
context_page_description: Under the Whyte notation for the classification of steam locomotives, 4-6-2 represents the wheel arrangement of four leading wheels on two axles, six powered and coupled driving wheels on three axles and two trailing wheels on one axle. The 4-6-2 locomotive became almost globally known as a Pacific type.
context_section_description: The first locomotives with a Pacific wheel arrangement in the Cape were two tank locomotives that entered service in 1896 on the private Metropolitan and Suburban Railway that operated a suburban passenger service between Cape Town and Sea Point. In 1901, both locomotives were sold to the Mashonaland Railway.
  Three Class 5 and one experimental Karoo tender locomotive variants were introduced on the Cape Government Railways (CGR) between 1903 and 1912.
  In 1903, the first two Karoo locomotives entered passenger service on the CGR. It was a development of the CGR Class 6 2-6-2 and was designed by Chief Locomotive Superintendent H.M. Beatty. The locomotives, built by Kitson and Company, were acquired to cope with the increasing weight of passenger trains on the one in eighty ruling gradient between Beaufort West and De Aar in the Karoo, hence the Karoo Class name. In 1912, when they came onto the SAR roster, they were designated Class 5A.
  Following on the success of the first two Karoo Class locomotives, a further four were ordered from Beyer, Peacock and Company in 1904. They were modified slightly in view of the experience gained with the original two. On the SAR, they were all designated Class 5B, until one was later reboilered with a Watson Standard no. 1 boiler and reclassified Class 5BR. All of them were later equipped with piston valve cylinders and superheaters.
  In 1907, the CGR placed a single experimental three-cylinder compound Pacific in service, based on the second Karoo Class. Built by the North British Locomotive Company (NBL), it was not classified and was simply referred to as the Three Cylinder Compound. The cylinders were arranged in the Smith system of compounding, with a single high-pressure cylinder situated between the two low-pressure cylinders. The locomotive had a bar frame, Walschaerts valve gear and used saturated steam. Compared to a simplex two-cylinder Karoo, the compound could take a heavy train up a long continuous grade at a much higher speed, while experienced drivers found it could outperform the Karoo in terms of power as well as fuel and water consumption. In 1912, the SAR classified it as Class Experimental 1.
  The Enlarged Karoo, built by Vulcan Foundry, was one of the locomotive types that were designed and ordered by the CGR before the SAR was established and that ended up being delivered to the newly established national railways of the Union of South Africa in 1912. It was a larger and heavier version of the Class 5B, with a higher pitched boiler, Belpaire firebox, larger diameter leading and coupled wheels and larger cylinders. The four locomotives were designated Class 5. One of them was later reboilered with a Watson Standard no. 1 boiler, equipped with a superheater and reclassified to Class 5R.
caption: Ex CGR Karoo Class, SAR Class 5A
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