South African Class 15A 4-8-2 Explained

South African Class 15A & 15AR 4-8-2
Hatnote:♠ Class 15A as built with a Belpaire firebox
Class 15AR rebuilt with a Watson Standard boiler
Steel firebox - Copper firebox
Powertype:Steam
Designer:South African Railways
Builder:North British Locomotive Company
Beyer, Peacock & Company
J.A. Maffei
Serialnumber:NBL 20556-20560, 20843-20850, 21054-21063, 21436-21441, 21502-21505, 21718-21737, 22736-22750
BP 5955-5974, 5978-5987
Maffei 5625-5645
Buildmodel:Class 15A
Builddate:1914-1925
Totalproduction:119
Whytetype:4-8-2
Driver:2nd coupled axle
Leadingdiameter:NaN0NaN0
Coupleddiameter:570NaN0
Trailingdiameter:330NaN0
Tenderdiameter:340NaN0
Wheelbase:60feet
Engine Total:33feet
Leading:6feet
Coupled:150NaN0
Tender Total:16feet
Tenderbogie:4feet
Over Couplers:68feet
Height:♠ 12feet
12feet
Frametype:Plate
Axleload:♠ 16lt
16lt
Leadingbogie/Pony:♠ 15lt
16lt
16lt
Coupled 1:♠ 16lt
16lt
Coupled 2:♠ 16lt
16lt
16lt
Coupled 3:♠ 16lt
16lt
Coupled 4:♠ 16lt
16lt
Trail Bogie/Pony:♠ 12lt
12sigfig=4NaNsigfig=4
12lt
Tenderbogieload:Bogie 1: 27lt
Bogie 2: 23lt
Tenderaxle:13lt
Weightondrivers:♠ 66sigfig=4NaNsigfig=4
65lt
66lt
Locoweight:♠ 94lt
94lt
94lt
Tenderweight:51lt
Locotenderweight:♠ 145lt
145lt
145lt
Tendertype:MP1 (2-axle bogies)
MP, MP1, MR, MS, MT, MT1, MT2, MX, MY, MY1 permitted
Fueltype:Coal
Fuelcap:101NaN1
Watercap:4250sigfig=3NaNsigfig=3
Fireboxtype:♠ Belpaire, combustion chamber
Round-top
Firearea:♠ 40square feet
37square feet
Boiler:Watson Standard no. 2A
Pitch:♠ 7feet
8feet
Diameterinside:♠ 5feet
5feet
Lengthinside:♠ 190NaN0
21feet
21feet
Smalltubediameter:♠ 113: NaN0NaN0
87: NaN0NaN0
Largetubediameter:♠ 21: NaN0NaN0
30: NaN0NaN0
Boilerpressure:♠ 1850NaN0
1900NaN0
Safetyvalvetype:♠ Ramsbottom - Pop
Totalsurface:♠ 2026square feet
2313square feet
Tubearea:♠ 1834square feet
2171square feet
Fireboxarea:♠ 192square feet
142square feet
Superheaterarea:♠ 478square feet
537square feet
Cylindercount:Two
Cylindersize:220NaN0 bore
280NaN0 stroke
Valvegear:Walschaerts
Valvetype:Poppet (No. 2100), Piston (Others)
Coupling:Johnston link-and-pin
AAR knuckle (1930s)
Tractiveeffort:♠ 32990lbf @ 75%
33880lbf @ 75%
Operator:South African Railways
Swaziland Railway
Operatorclass:Class 15A & 15AR
Numinclass:119
Fleetnumbers:1571-1575, 1781-1828, 1839-1858, 1961-1970, 2011-2025, 2080-2100
Deliverydate:1914-1925
Firstrundate:1914
Withdrawndate:1980s
Notes:Most leading coupled axles had flangeless wheels

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 wheel arrangement in service, delivered in ten batches from three manufacturers.[1]

Manufacturers

The Classes 15 and 15A were the final development of the plate-framed Mountain locomotive designed by D.A. Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR) 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 21feet to 190NaN0. 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.[1]

Characteristics

The locomotives had NaN0NaN0 thick plate frames and piston valves, actuated by Walschaerts valve gear.[1]

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.[4]

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.[1] [4]

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.[1]

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.[5] [6]

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.[1] [5] [6]

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.[4] [7]

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.[5] [6]

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.[1]

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.[8]

Works numbers

The table lists the Class 15A engine numbers, builders, years built, works numbers and eventual classifications.[5] [6]

Preservation

Number Owner Location
1791 Bloemfontein Locomotive Depot
1970 Greg Mc.Lennan Epping Industria, Cape Town
1798 Queenstown Locomotive Depot
1820 Krugersdorp Locomotive Depot
1840 Klipplaat Locomotive Depot
1850 Bloemfontein Locomotive Depot
1963 Railway Society of South Africa Hilton Station
1966 Queenstown Locomotive Depot
2012 Queenstown Locomotive Depot
2016 Municipality Queenstown Casino
2093 Queenstown Locomotive Depot
2100 Queenstown Locomotive Depot

Notes and References

  1. Espitalier, T.J.; Day, W.A.J. (1945). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued). South African Railways and Harbours Magazine, August 1945. pp. 593-594.
  2. North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  3. Beyer, Peacock and Company production list, excluding Garratts, Customer List V1 04.08.02
  4. Espitalier, T.J.; Day, W.A.J. (1945). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued). South African Railways and Harbours Magazine, July 1945. p. 516.
  5. South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 Aug 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 3'6" Gauge/Spoorwydte. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. p. 43.
  6. South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 Aug 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. 6a-7a, 41, 43.
  7. https://sites.google.com/site/soulorailway/home/system-1/part-3 Soul of A Railway, System 1, Part 1: Cape Town prior to the Second World War. Caption 6.
  8. https://sites.google.com/site/soulorailway/home/system-3-1/the-original-midland-main-line-pe-to-graaff-reinet-part-1 Soul of A Railway, System 3, Part 13: The Original Midland Main Line, Part 1, PE to Graaff-Reinet. Caption 48.

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