South African Class 24 2-8-4

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South African Class 24 2-8-4
SAR Class 24 3655 (2-8-4).JPG
No. 3655 "City of Cape Town" leaving Monument station, Cape Town, 8 August 2010
Type and origin
Power type Steam
Designer South African Railways
Builder North British Locomotive Company
Order number L976
Serial number 26313-26412 [1][2]
Model Class 24
Build date 1949-1950
Total produced 100
Specifications
Configuration 2-8-4 "Berkshire"
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading wheel
diameter
30 in (762 mm)
Driver diameter 51 in (1,300 mm)
Trailing wheel
diameter
30 in (762 mm)
Wheelbase Total: 65 ft 3 in (19.888 m)
Engine:
13 ft 6 in (4.115 m) coupled
4 ft 6 in (1.372 m) bogie
31 ft (9.449 m) total
Tender:
8 ft 8 in (2.642 m) bogie
24 ft 7.25 in (7.499 m) total
Length 74 ft 9.25 in (22.790 m) total
Height 12 ft 10.125 in (3.915 m)
Frame Cast frame
Axle load 11.5 long tons (11.7 t) on 2nd driver
Weight on drivers 45.2 long tons (45.9 t)
Locomotive weight 72.9 long tons (74.1 t)
Tender weight 61,500 lb (27,900 kg) empty
56.55 long tons (57.5 t) w/o
Locomotive and tender
combined weight
147,000 lb (66.7 t) empty
129.45 long tons (131.5 t) w/o
Tender type MY Torpedo
* 3 axle Buckeye bogies
* 34 in (864 mm) wheels
* Length 34 ft 3.25 in (10.446 m)
Fuel type Coal
Fuel capacity 9 long tons (9.1 t)
Water capacity 4,520 imp gal (20,500 l)
Boiler 5 ft (1.524 m) inside diameter
17 ft 9 in (5.410 m) inside length
8 ft (2.438 m) pitch
Boiler pressure 200 psi (1,380 kPa)
Firegrate area 36 sq ft (3.345 m2)
Heating surface:
– Tubes
76 tubes 2.5 in (63.5 mm) diameter
24 tubes 5.5 in (140 mm) diameter
1,497 sq ft (139.076 m2)
– Flues 16 sq ft (1.486 m2)
– Firebox 123 sq ft (11.427 m2)
– Total 1,636 sq ft (151.989 m2)
Superheater area 380 sq ft (35.303 m2)
Cylinders Two
Cylinder size 19 in (483 mm) bore
26 in (660 mm) stroke
Valve gear Walschaerts
Performance figures
Tractive effort 27,600 lbf (123 kN) at 75% pressure
Career
Operator(s) South African Railways [3]
Class Class 24
Number in class 100
Number(s) 3601-3700
Delivered 1949-1950
First run 1949

The South African Class 24 2-8-4 of 1949 is a South African steam locomotive from the South African Railways era.

In 1949 and 1950 the South African Railways placed one hundred Class 24 branchline steam locomotives with a 2-8-4 Berkshire type wheel arrangement in service.[3]

Manufacturer[edit]

The Class 24 2-8-4 Berkshire type branchline steam locomotive was designed by Dr. M.M. Loubser, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1939 to 1949. The locomotives were built by North British Locomotive Company (NBL) of Glasgow, who delivered one hundred of them in 1949 and 1950, numbered in the range from 3601 to 3700. The cast engine main frames and the Buckeye bogies for the tenders were supplied by General Steel Castings of Eddystone, Pennsylvania.[1]

One of these locomotives, Class 24 number 3675, was the two thousandth locomotive to be built by NBL for the SAR and, to commemorate this, a ceremony was conducted in Cape Town to name the locomotive Bartolomeu Dias, after the famous Portuguese navigator who discovered the Cape of Good Hope in May 1488 and named it the "Cape of Storms" (Cabo das Tormentas). The ceremony was attended by the South African Minister of Transport and heads of departments of the SAR, as well as by the chairman and managing director of NBL.[1]

Characteristics[edit]

The Class 24 had a one-piece steel main frame cast integrally with the cylinders, including the cylinder hind covers, smokebox support frame, stays and various brackets, all of which would normally be separate items riveted or bolted onto the frames. Advantages of this arrangement are reduced maintenance and less time spent in shops. It was the first South African steam locomotive to be built using this technique.[1]

They were built with Watson Standard no. 1 boilers and they used Type MY tank wagon type tenders, similar in appearance to the American Vanderbilt type tenders with cylindrical water tanks. The tenders ran on three-axle Buckeye bogies and became commonly known as Torpedo tenders.[1][4][5]

Service[edit]

The Class 24 was built to replace the old Class 6, Class 7 and Class 8 locomotives in branchline service on light 45 pounds per yard (22 kilograms per metre) rail. When introduced, an elaborate programme was drawn up showing on which systems and on what sections they were to be employed.[1][6]

  • The Cape Western System, on the Saldanha-Kalbaskraal, Porterville-Hermon and Prince Alfred Hamlet-Wolseley sections.
  • The Cape Midland System, on the Knysna-George, Alexandra-Barkly Bridge, Kirkwood-Addo and Somerset East-Cookhouse sections.
  • The Orange Free State System, on the Dover-Vredefort, Wolwehoek-Arlington-Marquard, Theunissen-Winburg, Westleigh-Orkney and Vierfontein-Bultfontein sections.
  • The Eastern Transvaal System, on the Zoekmekaar-Komatipoort, Barberton-Kaapmuiden, Middelburg-Stoffberg, Brits-Beestekraal and Zebedela-Naboomspruit sections.
  • The South West Africa System, on the De Aar-Karasburg and Keetmanshoop-Windhoek sections.
SAR Class 24 3668 (2-8-4) ID.JPG

Most of them went to South West Africa (Namibia), where fifty-five of them would be in operation. From some time between 1955 and 1959 they were also employed on the Keetmanshoop-Walvisbaai section. They remained in that territory until strengthening of the track and the introduction of diesel traction made them available to be employed elsewhere.[1][5]

Some eventually also worked on the Selati line past Skukuza in the Kruger National Park and in 1969 and 1970, during the last years of their service life, also briefly on the Hutchinson to Calvinia line in the Karoo.[1][5][7][8]

Other branchlines served by the Class 24 include Breyten to Lothair, Nylstroom to Vaalwater and Port Elizabeth to Alexandra. As a relatively powerful locomotive, they were also useful as suburban locomotives, a role they served in on the Springs-Nigel commuter line until electrification. Heavy overhauls were done at Bloemfontein. The only province where they were unknown was Natal.[6]

Preservation[edit]

They were withdrawn from service and retired in the mid 1980s. By 2010 preserved Class 24 locomotives included number 3668, which served on the Outeniqua Choo Tjoe tourist line between Knysna and Mosselbaai until the operation was ceased in 2010, and number 3655 "Jenny" that is still based at Monument station in Cape Town and is regularly being run by volunteers of the Friends of Atlantic Rail. In Gauteng, number 3664 "Jo-Anna" is still being operated by the Friends of the Rail.[5][9][10]

No. 3620 is preserved in Cairns, having been exported to Australia in January 2001 for operation on the Kuranda Scenic Railway.

Sides illustrated[edit]

The main picture and the following photographs offer views of both sides of the Class 24 locomotive and its unique tender. The main picture shows number 3655, the "City of Cape Town," leaving Monument station in Cape Town on 8 August 2010. This locomotive was rechristened "Jenny" in 2011, in honour of the late Jenny Pretorius, a much respected South African steam preservationist.

See also[edit]

References[edit]

  1. ^ a b c d e f g h Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 105–107. ISBN 978-0-7153-5427-8. 
  2. ^ North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  3. ^ a b South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  4. ^ Keetmanshoop (Namibia) SAR class 24 no's 3611 & 3612
  5. ^ a b c d Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10–11, 76. ISBN 0869772112. 
  6. ^ a b Durrant, A E (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. p. 106. ISBN 0715386387. 
  7. ^ Calvinia - SAR Class 24 no 3608 "Makadas"
  8. ^ Skukuza - Selati Train Restaurant - SAR class 24 no.3638
  9. ^ "Steam Locomotives - Class 24, No 3664". Friends of the Rail. Retrieved 15 July 2011. 
  10. ^ "Steam Locomotives - Class 24, No 3664 - FOTR Forum". Friends of the Rail. Retrieved 23 Nov 2011.