The South African Railways Class 15F 4-8-2 of 1938 is a steam locomotive.
The Class 15F was the most numerous steam locomotive class in South African Railways service. Between 1938 and 1948, 255 of these locomotives with a 4-8-2 Mountain type wheel arrangement entered service.Espitalier, T.J.; Day, W.A.J. (1947). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued). South African Railways and Harbours Magazine, February 1947. pp. 129-131.
Manufacturers
The Class 15F 4-8-2 Mountain type steam locomotive was designed by W.A.J. Day, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1936 to 1939, based on the design of the Class 15E by his predecessor, Allan Griffiths Watson, and later modified again by his successor, M.M. Loubser. It was built in five batches by four locomotive manufacturers in Germany and the United Kingdom over a period of ten years spanning World War II. The first 21 were built in Germany in 1938. Seven were delivered by Berliner Maschinenbau, numbered in the range from 2902 to 2908, and fourteen by Henschel & Son, numbered in the range from 2909 to 2922.Henschel-Lieferliste (Henschel & Son works list), compiled by Dietmar Stresow
Another 44 were built by the North British Locomotive Company (NBL) of Glasgow in 1938. They were delivered in 1939, numbered in the range from 2923 to 2966.North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser Locomotive building was interrupted by World War II, but because of a critical motive power shortage that developed in South Africa during the war, manufacturing of the Class 15F was resumed even before hostilities had ceased. In 1944, production started on thirty locomotives by Beyer, Peacock & Company (BP), delivered later that same year and numbered in the range from 2967 to 2996.Beyer, Peacock & Company production list, excluding Garratts, Customer List V1 04.08.02 In 1945, sixty were built and delivered by NBL, numbered in the range from 2997 to 3056. The final batch of 100 Class 15Fs were built by NBL in 1946 and 1947 and delivered between 1946 and 1948, numbered in the range from 3057 to 3156.
Lineage The Class 15F represented the ultimate stage in a long history of development spanning thirty years. The first Class 15 4-8-2 tender locomotive entered SAR service in 1914. It sported a grate, a boiler pressure of , a maximum axle load of and diameter coupled wheels. Later models incorporated major improvements in succession, until the Class 15CA was commissioned in 1926 with a grate, a boiler pressure of , a maximum axle load of and diameter coupled wheels.4-8-2 Class "15F" Locomotives for the South African Railways Railway Gazette 20 September 1946
Characteristics The Class 15F locomotive was similar to its predecessor Class 15E, but it was built with Walschaerts valve gear as specified by Day, who was not a protagonist of rotary cam poppet valve gear. This and some other differences led to these engines being designated Class 15F. The locomotives used Stone's electric lighting, with a 150 watt Tonum E type headlight, cab lighting which included a light over the reversing controls, a bunker light and rear headlights on the tender. The locomotive was capable of traversing curves of radius with gauge widening.
The Class 15F was delivered with a Watson Standard no. 3B boiler and a Watson cab. During the 1930s, Day's predecessor as CME, A.G. Watson, designed a standard boiler type as part of his standardisation policy. Many serving locomotives were reboilered with these Watson Standard boilers and in the process most of them were also equipped with Watson cabs with their distinctive slanted fronts, compared to the conventional vertical fronts of their original cabs. New locomotives that were acquired in the Watson era and later, such as the Class 15F, were built with such boilers and cabs.South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 August 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 3'6" Gauge/Spoorwydte. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. pp. VIII, 46.South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 August 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 2'0" & 3'6" Gauge/Spoorwydte, Steam Locomotives/Stoomlokomotiewe. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. pp. VIII, 6a-7a, 21-21A, 46.
To fit within the loading gauge, the Watson Standard no. 3B boiler was domeless. The maximum height of the locomotive was , the maximum width and the length over coupler faces .
The pre-war locomotives were equipped with two large inclined Ross-pop safety valves, mounted on the upper sides of the boiler just ahead of the firebox and aimed about 80 degrees apart. When these inclined valves blew off under a station canopy, bystanders often received a shower of slimy wet soot. After the war, they were replaced by four smaller Ross-pop valves at the highest point of the boiler that blew off straight up.Soul of A Railway, System 7, Western Transvaal, based in Johannesburg, Part 2. Johannesburg between the Home Signals, Part 2. Caption 19. (Retrieved 21 March 2017)Soul of A Railway, System 7, Western Transvaal, based in Johannesburg, Part 10. South-Eastwards as far as Volksrust (3rd part) by Les Pivnic. Caption 15. (Retrieved 11 April 2017)Soul of A Railway, System 7, Western Transvaal, based in Johannesburg, Part 12. South-Eastwards as far as Volksrust (Part 5) by Les Pivnic. Captions 32 & 33. (Retrieved 25 April 2017)
The cylinder barrels had cast iron liners. The valve gear, brake gear and the hubs on the coupled wheels were fitted with soft grease lubricating nipples while the bronze axle boxes and connecting and coupling rods had hard grease lubrication. The leading and trailing wheels were fitted with roller bearings. The axle boxes and motion were similar to those of the Classes 15CA and 23 and were interchangeable in most cases. The weight of the reciprocating parts on each side of the engine was , of which 20% was balanced to ensure that the hammer blow per wheel would not exceed at and with the overbalance equally divided on all the coupled wheels.
Pre-war models The pre-war Class 15Fs were manually stoked and were delivered without smoke deflectors. The original 21 Berliner- and Henschel-built engines remained hand-fired for the full duration of their working lives. On the pre-war NBL-built engines, on the other hand, provision was made in the design to later convert them to mechanical stoking. A mechanical stoker was tested on no. 2923 before the remaining locomotives of that group were all equipped with such stokers by the late 1940s. Their brake systems consisted of steam brakes on the engines and vacuum brakes on the tenders.
One of the Henschel-built locomotives, no. 2916, is documented as having had a lighter all-up weight and different axle loads than the rest of the engines from the same batch, although its adhesive weight was more than a ton heavier. While sources are silent on the reason for the differences, it is known that this engine was oil-fired, although it is not clear whether it was delivered as an oil-burner or modified post-delivery.
Post-war models The post-war locomotives were built to the design and specifications of Dr. M.M. Loubser, who succeeded Day as CME in 1939. His specifications included mechanical stokers, vacuum brakes on the coupled wheels as well as the tenders, with two diameter brake cylinders on the engine and two diameter cylinders on the tender, and elephant-ear smoke deflectors instead of smokebox handrails.Soul of A Railway, System 7, Western Transvaal, based in Johannesburg, Part 6. Germiston, the Steam and Diesel Running Sheds by Les Pivnic. Captions 16, 20. (Retrieved 7 April 2017)
The engine's vacuum brake cylinders were fitted outside the main frames under the running boards on each side, between the second and third pairs of coupled wheels. The vacuum brake operated automatically whenever the train brakes were applied. The use of vacuum braking instead of steam braking became standard practice on locomotives built from 1944 onwards and was welcomed by SAR drivers, who were always reluctant to make use of steam brakes for fear of skidding the coupled wheels. In practice, the trigger on the steam brake attachment to isolate the proportional device which admitted steam to the brake cylinder automatically upon the application of the vacuum brake, was invariably wedged down with a wooden peg by drivers to eliminate the steam brake entirely.
Loubser also modified the leading bogie to have swing links with three-point suspension which eliminated the side control springs that were used on earlier versions. As a unit, the modified bogie was interchangeable with those of earlier versions and with those of the Classes 15E and 23. The leading bogie had a side-play of while the trailing Bissel truck had a side-play of .
The engines from Beyer, Peacock were war-time austerity models on which planished steel boiler lagging was replaced by ordinary steel lagging, while cosmetic dressing items like stainless steel lagging bands, chrome-plated handrails and rounded corners on the front of the firebox lagging were absent or replaced by unplated items. While the boiler barrels of the pre-war engines were of nickel steel, the austerity locomotives had boiler barrels made of carbon steel with steel plates of greater thickness. When it was subsequently found that the increased thickness was unnecessary, thick carbon steel plates were used on later orders, the same thickness as earlier used with nickel steel plates, which resulted in a desirable reduction in axle loads.
Like the pre-war NBL-built engines, the early post-war locomotives built by BP and NBL in 1944 and 1945 were delivered with Type JT tenders which had a coal capacity and a water capacity. As delivered, they were arranged for manual stoking, but with provision made in their design for their subsequent conversion to mechanical stoking. All these locomotives were equipped with mechanical stokers post-delivery.
The locomotives in the final batch of 100 that were received from NBL in 1947 and 1948, numbers 3057 to 3156, were delivered new complete with mechanical stokers. These engines were delivered with Type ET tenders, which also had a coal capacity, but a smaller water capacity to accommodate the mechanical stoker mechanism, while its empty weight was more due to the additional stoking equipment. These appear to have been the only differences between the Types JT and ET tenders. Apart from these differences, the post-war locomotives were identical to the earlier ones. Elephant ear smoke deflectors were later installed on the pre-war locomotives as well.
Locomotive naming Although the naming of locomotives in South Africa dates back to the Cape Town Railway & Dock 0-4-2 locomotives of 20 March 1860 and the Natal Railway's 0-4-0WT Natal of 13 May 1860, it was rarely done. In 1945, the Minister of Transport at the time, the Honourable F. C. Sturrock MP, instructed that a number of Classes 15F and 23 engines should be named after various South African cities and towns and fitted with suitable nameplates in both official languages. The decorative plates were fitted to the sides of the smokebox or to the elephant ear smoke deflectors of engines which were so equipped. Twelve Class 15F locomotives were named. 3044 Kroonstad 3045 Harrismith 3046 City of Bloemfontein 3047 City of Pretoria 3049 City of Johannesburg 3050 Springs 3051 Vereeniging 3052 Brakpan 3053 Benoni 3054 Bethlehem 3055 Germiston 3056 Potchefstroom
In later years, some of these names migrated to other engines and classes, with several eventually ending up on Classes 23 and 25NC locomotives.