South African Class 4A 4-8-2

South African Class 4A & 4AR 4-8-2

No. 1559 at Hutchinson, Cape, 11 November 1916
Type and origin
♠ Class 4A as built with a round-topped firebox
Class 4AR rebuilt with a Watson Standard boiler
Steel firebox - Copper firebox
Power type Steam
Designer Cape Government Railways
(H.M. Beatty)
Builder North British Locomotive Company
Serial number 20225-20234
Model CGR 4-8-2
Build date 1913
Total produced 10
Specifications
Configuration 4-8-2 (Mountain)
Driver 2nd coupled axle
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading dia. 28 12 in (724 mm)
Coupled dia. 54 in (1,372 mm)
Trailing dia. 33 in (838 mm)
Tender wheels 33 12 in (851 mm) as built
34 in (864 mm) retyred
Wheelbase 58 ft 5 38 in (17,815 mm)
  Engine 32 ft 2 in (9,804 mm)
  Leading 6 ft 2 in (1,880 mm)
  Coupled 14 ft 5 in (4,394 mm)
  Tender 16 ft 1 in (4,902 mm)
  Tender bogie 4 ft 7 in (1,397 mm)
Wheel spacing
(Asymmetrical)
1-2: 4 ft 10 in (1,473 mm)
2-3: 4 ft 9 in (1,448 mm)
3-4: 4 ft 10 in (1,473 mm)
Length:
  Over couplers 66 ft 3 58 in (20,209 mm)
Height ♠ 12 ft 10 in (3,912 mm)
12 ft 11 14 in (3,943 mm)
Axle load ♠ 15 LT 12 cwt (15,850 kg)
14 LT 11 cwt (14,780 kg)
  Leading ♠ 12 LT (12,190 kg)
13 LT 14 cwt (13,920 kg)
  1st coupled ♠ 15 LT 2 cwt (15,340 kg)
14 LT 11 cwt (14,780 kg)
  2nd coupled ♠ 15 LT 12 cwt (15,850 kg)
14 LT 9 cwt (14,680 kg)
  3rd coupled ♠ 15 LT 10 cwt (15,750 kg)
14 LT 7 cwt (14,580 kg)
  4th coupled ♠ 15 LT 10 cwt (15,750 kg)
14 LT 4 cwt (14,430 kg)
  Trailing ♠ 11 LT 14 cwt (11,890 kg)
10 LT 4 cwt (10,360 kg)
  Tender bogie Bogie 1: 23 LT 9 cwt (23,830 kg)
Bogie 2: 23 LT 16 cwt (24,180 kg)
  Tender axle 11 LT 18 cwt (12,090 kg)
Adhesive weight ♠ 61 LT 14 cwt (62,690 kg)
57 LT 11 cwt (58,470 kg)
Loco weight ♠ 85 LT 8 cwt (86,770 kg)
81 LT 9 cwt (82,760 kg)
Tender weight 47 LT 5 cwt (48,010 kg) w/o
Total weight ♠ 132 LT 13 cwt (134,800 kg) w/o
128 LT 14 cwt (130,800 kg) w/o
Tender type XM (2-axle bogies)
XC, XC1, XD, XE, XE1, XF, XF1, XF2, XJ, XM, XM1, XM2, XM3, XM4, XP1, XS permitted
Fuel type Coal
Fuel capacity 8 LT (8.1 t)
Water cap 4,000 imp gal (18,200 l)
Firebox type Round-top
  Firegrate area 37 sq ft (3.4 m2)
Boiler:
  Model Watson Standard no. 2
  Pitch ♠ 7 ft 6 in (2,286 mm)
8 ft (2,438 mm)
  Diameter ♠ 5 ft 6 38 in (1,686 mm)
5 ft 7 12 in (1,714 mm)
  Tube plates ♠ 18 ft 3 in (5,563 mm)
19 ft 4 in (5,893 mm)
19 ft 3 58 in (5,883 mm)
  Small tubes144: 2 14 in (57 mm)
81: 2 12 in (64 mm)
  Large tubes22: 5 38 in (137 mm)
30: 5 12 in (140 mm)
Boiler pressure 180 psi (1,241 kPa)
Safety valve Cole's Pop
Heating surface ♠ 2,292 sq ft (212.9 m2)
2,075 sq ft (192.8 m2)
  Tubes ♠ 2,106 sq ft (195.7 m2)
1,933 sq ft (179.6 m2)
  Firebox ♠ 186 sq ft (17.3 m2)
142 sq ft (13.2 m2)
Superheater:
  Heating area ♠ 554 sq ft (51.5 m2)
497 sq ft (46.2 m2)
Cylinders Two
Cylinder size 21 12 in (546 mm) bore
28 in (711 mm) stroke
Valve gear Walschaerts
Valve type Piston
Couplers Bell link-and-pin
AAR knuckle (1950s)
Performance figures
Tractive effort 32,360 lbf (143.9 kN) @ 75%
Career
Operators South African Railways
Class Class 4A, Class 4AR
Number in class 10
Numbers 1551-1560
Delivered 1913-1914
First run 1913
Withdrawn 1974
The leading coupled axle had flangeless wheels

The South African Railways Class 4A 4-8-2 of 1913 was a steam locomotive.

In 1913 and 1914, ten Class 4A steam locomotives with a 4-8-2 Mountain type wheel arrangement were placed in service by the South African Railways.[1][2][3]

Manufacturer

H.M. Beatty

The Class 4 Mountain type locomotive was designed as a heavy mixed traffic locomotive by H.M. Beatty, the last Chief Locomotive Superintendent of the Cape Government Railways (CGR), at the Salt River shops. Soon after the South African Railways (SAR) was established in 1912, an order was placed with North British Locomotive Company for a further ten locomotives of this type. They were delivered late in 1913 and were designated Class 4A, numbered in the range from 1551 to 1560.[2][3][4]

The Class 4A were the only locomotives to be delivered with Type XM tenders, which had a coal capacity of 8 long tons (8.1 tonnes) and a water capacity of 4,000 imperial gallons (18,200 litres).[5][6]

Characteristics

The Class 4A locomotive was an improved version of the predecessor Class 4. It had a superheater added, which further resulted in the slide valves and Stephenson valve gear having to be replaced with piston valves and Walschaerts valve gear. The boilers were similar to those of the Class 4, except for the superheater and the length between tube-plates, which was 3 inches (76 millimetres) greater. The bar frames were identical to that of the Class 4, but the cylinders were of a 1 inch (25 millimetres) larger bore. The engines were erected at the Salt River shops in Cape Town during November 1913. Like their two forerunners, they were excellent steamers and, with the modifications, gave a much better performance.[1][2][3]

Watson Standard boilers

In the 1930s, many serving locomotives were reboilered with a standard boiler type, designed by then Chief Mechanical Engineer A.G. Watson as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.[3][5][6]

All ten Class 4A locomotives were reboilered with Watson Standard no. 2 boilers during 1935 and reclassified to Class 4AR. The new boiler's pitch was 6 inches (152 millimetres) higher than on the Class 4A. In the process they underwent some additional modifications. They were equipped with Watson cabs, with their distinctive slanted fronts, compared to the conventional vertical fronts of their original cabs. The trailing Bissel truck remained unaltered, but the side control was redesigned and spring compensation was extended to include the Bissel. This was one of the rare instances where reboilering actually appreciably reduced the total weight of the engine, from 85 long tons 8 hundredweight (86,770 kilograms) to 81 long tons 9 hundredweight (82,760 kilograms).[2][3][5][6]

An obvious visual 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, but this was not always the case, as illustrated. In the case of the Class 4AR, an even more obvious visual difference is the Watson cab.[5][6]

Service

Their first ten years of service were spent working both passenger and goods trains on various sections of the Cape mainline. At first they worked out of Cape Town, but when more powerful locomotives became available, they were transferred to the Karoo, working between Touws River and Kimberley and also northward from Kimberley to Mafeking. They were then transferred to the Reef, from where they regularly served on the Zeerust, Breyten and Volksrust lines, while also being employed in a variety of suburban and local train workings.[1][3]

Armoured Class 4A no. 1554, 1942

During the Second World War, Class 4A no. 1554 was equipped with tempo­rary protective armour to serve as the locomotive of an armoured train, which was based at Mapleton Camp. The picture shows the locomotive and armoured train being in­spect­ed during 1942 by the Honourable F.C. Sturrock MP, South Africa’s Minister of Transport at the time.

The last Class 4AR locomotive was withdrawn from shunting operations on the West Rand in 1974. Some remained working in industrial service for several more years, with the last one being finally retired from Apex Colliery in 1983.[3][7]

Rhodesia Railways

A lighter version of the Class 4A was built by NBL for the Rhodesia Railways (RR). It was designated the RR 10th Class and was used on the long section south from Bulawayo in Southern Rhodesia (now Zimbabwe) through Bechuanaland Protectorate (now Botswana) to Mafeking in the Cape Province.[7]

Like the SAR Class 4A, the RR 10th Class had combustion chambers, the only RR locomotive class with this feature.[7]

Illustration

The main picture shows no. 1559, as built, on the Cape Town-Johannesburg train, taking water at Hutchinson in the Karoo on 11 November 1916.[1]

In the pictures of reboilered Class 4AR locomotives, one locomotive has the rectangular regulator cover just to the rear of the chimney, while the other, no. 1554, has a bolted on cover plate instead, flush with the boiler cladding. Both have Watson cabs, while the pictures of Class 4A locomotives show their original cabs with conventional vertical fronts.[5][6]

References

  1. 1 2 3 4 Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 12–13, 22–23, 137. ISBN 978-0-7153-5427-8.
  2. 1 2 3 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. 513.
  3. 1 2 3 4 5 6 7 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 38–39. ISBN 0869772112.
  4. North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  5. 1 2 3 4 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. 1 2 3 4 5 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. 1 2 3 Durrant, A E (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. p. 13. ISBN 0715386387.
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