South African Class 15A 4-8-2


The South African Railways Class 15A 4-8-2 of 1914 was a steam locomotive.
Between 1914 and 1925, the South African Railways placed 119 Class 15A steam locomotives with a 4-8-2 Mountain type wheel arrangement in service, delivered in ten batches from three manufacturers.

Manufacturers

The Classes 15 and 15A were the final development of the plate-framed Mountain locomotive designed by D.A. Hendrie, Chief Mechanical Engineer of the South African Railways from 1910 to 1922. Of the whole Hendrie Mountain family, the Class 15A was the most numerous and proved to be his most useful.
The predecessor Class 15 locomotives had one flaw, their excessively long fire tubes. When more locomotives of the type were ordered, Hendrie improved the boiler by adding a combustion chamber in the firebox, which shortened the distance between tube plates from to. When the first five of these redesigned locomotives were delivered in 1914, they were designated Class 15A. Altogether 119 were ultimately built in ten batches by three manufacturers. Being wartime, initial production and delivery occurred in dribs and drabs.
The locomotives had thick plate frames and piston valves, actuated by Walschaerts valve gear.

Firebox

To reduce the weight on the trailing wheels, steel fireboxes were originally used instead of copper. Some locomotives in Natal had been fitted with steel fireboxes years previously and the results were fairly good, but wherever water supplies were of poor quality, steel fireboxes gave a lot of trouble and necessitated the introduction of water treatment plants to prevent corrosion. This reintroduction of steel fireboxes eventually led to its widespread use on all the larger locomotive types, but it also forced the SAR to adopt locomotive water treatment as a general policy.
The first five locomotives of 1914 were delivered with steel fireboxes. In the case of the Classes 15 and 15A, it was still early days for water treatment and enough trouble was experienced to result in their steel fireboxes being replaced with copper fireboxes. Hendrie followed a conservative policy in this respect and the majority of the rest of the Class 15A fleet were originally fitted with copper fireboxes. Steel fireboxes were only to be fitted in large numbers by his successor, Colonel F.R. Collins DSO, and only the last batch of 1925, supplied by Maffei, were delivered with steel fireboxes.

Valve gear experiment

The last Class 15A locomotive, Maffei-built no. 2100, was fitted with Lentz Rotary Cam Poppet valve gear as an experiment, but this was later replaced with Walschaerts valve gear and piston-valve cylinders, thereby turning no. 2100 into a standard Class 15A.

Watson Standard boilers

During the 1930s, many serving locomotives were reboilered with a standard boiler type designed by A.G. Watson, CME of the SAR from 1929 to 1936, as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.
When Class 15A locomotives were reboilered with Watson Standard no. 2A boilers, they were therefore reclassified to Class 15AR. Early conversions were equipped with copper and later conversions with steel fireboxes. In the process, they were also equipped with Watson cabs with their distinctive slanted fronts, compared to the conventional vertical fronts of their original cabs, while the cab platform was extended over the front end of the tender underframe. Many of the reboilered engines were later fitted with Type MR or Type MT tenders.
Since the only difference between the as-delivered Class 15 and Class 15A lay in the length of their boilers and whether they were built with or without combustion chambers, both models were reclassified to Class 15AR when they were reboilered with Watson Standard boilers. In the case of the Class 15A engines, reboilering replaced their combustion-chambered Belpaire boilers with less efficient Watson Standard boilers without combustion chambers and it was found that the rebuilds were inferior steamers compared with their non-rebuilt sister engines.
Their original Belpaire boilers were fitted with Ramsbottom safety valves, while the Watson Standard boiler was fitted with Pop safety valves. Another obvious difference between an original and a Watson Standard reboilered locomotive is usually a rectangular regulator cover, just to the rear of the chimney on the reboilered locomotive. In the case of the Class 15A and Class 15AR, two even more obvious differences are the Watson cab and the absence of the Belpaire firebox hump between the cab and boiler on the reboilered locomotives. In addition, during reboilering the early Class 15A models with curved down rear end running boards and narrow cabs were altered to straight rear end running boards with Watson cabs.

Service

The Class 15A, one of the best classes of mainline mixed traffic locomotives to see service in South Africa, was placed in service on the Cape mainline to Kimberley where they formed the mainstay of motive power for many years. The engine was a good utility type and gave a good account of itself on goods and passenger working alike. It is noted for reducing the running time of the Union Limited by 2½ hours in March 1922. When they were superseded on this section by more powerful types, they ended up working in all parts of the country and proved to be reliable, free-steaming locomotives which ran up high mileage figures between major overhauls.
As the reboilered Class 15AR, many ended up working in the Eastern Transvaal around Waterval Boven, in the Western Transvaal, Eastern Cape and the Orange Free State. During the 1960s, many were transferred to the Cape Midland and used mainly on the section from Port Elizabeth to Klipplaat and in passenger service on the Uitenhage suburban.
Near the end of their service lives in the early 1980s, they were all relegated to shunting work at centres all around the country, except for some which were hired out to Swaziland and which were still employed in mainline service on the Swaziland Railway until they were eventually replaced by diesel traction and retired. By the time they were withdrawn after more than sixty years in service, many of these locomotives had completed three million miles of heavy-duty mainline work.

Works numbers

The table lists the Class 15A engine numbers, builders, years built, works numbers and eventual classifications.

SAR no.		Builder
Year
Works
no.		Class
1571NBL19142055615AR
1572NBL19142055715AR
1573NBL19142055815AR
1574NBL19142055915AR
1575NBL19142056015AR
1781NBL19142084315AR
1782NBL19142084415AR
1783NBL19142084515AR
1784NBL19142084615AR
1785NBL19142084715AR
1786NBL19142084815AR
1787NBL19142084915AR
1788NBL19142085015AR
1789NBL19152105415AR
1790NBL19152105515AR
1791NBL19152105615A
1792NBL19152105715AR
1793NBL19152105815AR
1794NBL19152105915AR
1795NBL19152106015AR
1796NBL19152106115AR
1797NBL19152106215AR
1798NBL19152106315AR
1799NBL19162143615AR
1800NBL19162143715AR
1801NBL19162143815AR
1802NBL19162143915AR
1803NBL19162144015AR
1804NBL19162144115AR
1805NBL19172150215AR
1806NBL19172150315AR
1807NBL19172150415AR
1808NBL19172150515AR
1809NBL19192171815AR
1810NBL19192171915AR
1811NBL19192172015AR
1812NBL19192172115AR
1813NBL19192172215AR
1814NBL19192172315AR
1815NBL19192172415AR
1816NBL19192172515AR
1817NBL19192172615AR
1818NBL19192172715AR
1819NBL19192172815AR
1820NBL19192172915AR
1821NBL19192173015AR
1822NBL19192173115AR
1823NBL19192173215AR
1824NBL19192173315A
1825NBL19192173415AR
1826NBL19192173515AR
1827NBL19192173615AR
1828NBL19192173715AR
1839BP1920595515AR
1840BP1920595615AR
1841BP1920595715AR
1842BP1920595815AR
1843BP1920595915AR
1844BP1920596015AR
1845BP1920596115A
1846BP1920596215AR
1847BP1920596315AR
1848BP1920596415AR
1849BP1920596515AR
1850BP1920596615AR
1851BP1920596715A
1852BP1920596815AR
1853BP1920596915AR
1854BP1920597015AR
1855BP1920597115AR
1856BP1920597215AR
1857BP1920597315AR
1858BP1920597415AR
1961BP1921597815AR
1962BP1921597915AR
1963BP1921598015AR
1964BP1921598115AR
1965BP1921598215AR
1966BP1921598315AR
1967BP1921598415AR
1968BP1921598515AR
1969BP1921598615AR
1970BP1921598715A
2011NBL19212273615AR
2012NBL19212273715AR
2013NBL19212273815AR
2014NBL19212273915AR
2015NBL19212274015AR
2016NBL19212274115AR
2017NBL19212274215AR
2018NBL19212274315AR
2019NBL19212274415AR
2020NBL19212274515AR
2021NBL19212274615AR
2022NBL19212274715AR
2023NBL19212274815AR
2024NBL19212274915AR
2025NBL19212275015AR
2080Maffei1925562515AR
2081Maffei1925562615AR
2082Maffei1925562715AR
2083Maffei1925562815AR
2084Maffei1925562915AR
2085Maffei1925563015AR
2086Maffei1925563115AR
2087Maffei1925563215AR
2088Maffei1925563315AR
2089Maffei1925563415AR
2090Maffei1925563515AR
2091Maffei1925563615AR
2092Maffei1925563715AR
2093Maffei1925563815AR
2094Maffei1925563915AR
2095Maffei1925564015AR
2096Maffei1925564115AR
2097Maffei1925564215AR
2098Maffei1925564315AR
2099Maffei1925564415AR
2100Maffei1925564515AR

Preservation

NumberWorks nmrTHF / PrivateLeaselend / OwnerCurrent LocationOutside South Africa?
1791THFBloemfontein Locomotive Depot
1970PrivateGreg Mc.Lennan
1798THFQueenstown Locomotive Depot
1820THFKrugersdorp Locomotive Depot
1840THFKlipplaat Locomotive Depot
1850THFBloemfontein Locomotive Depot
1963PrivateRailway Society of South AfricaHilton Station
1966THFQueenstown Locomotive Depot
2012THFQueenstown Locomotive Depot
2016PrivateMunicipalityQueenstown Casino
2093THFQueenstown Locomotive Depot
2100THFQueenstown Locomotive Depot

Illustration

The main picture shows reboilered 1914-built Class 15A no. 1788 at Graaff Reinet on 4 April 1978. Differences between the various locomotive models are illustrated in the pictures below.
;Locomotives as built, with Belpaire fireboxes.
;Ex narrow cab Class 15AR locomotives, reboilered with Watson Standard no. 2A boilers.
;Ex wide cab Class 15AR locomotives, reboilered with Watson Standard no. 2A boilers.