No. 3655 City of Cape Town leaving Monument station, 8 August 2010
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Type and origin | |
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Power type | Steam |
Designer |
South African Railways (Dr. M.M. Loubser) |
Builder | North British Locomotive Company |
Order number | L976 |
Serial number | 26313-26412 |
Model | Class 24 |
Build date | 1949-1950 |
Total produced | 100 |
Specifications | |
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Configuration | 2-8-4 (Berkshire) |
Driver | 3rd coupled axle |
Gauge | 3 ft 6 in (1,067 mm) Cape gauge |
Leading dia. | 30 in (762 mm) |
Coupled dia. | 51 in (1,295 mm) |
Trailing dia. | 30 in (762 mm) |
Tender wheels | 34 in (864 mm) |
Minimum curve | 300 ft (91 m) |
Wheelbase | 65 ft 3 in (19,888 mm) |
• Engine | 31 ft (9,449 mm) |
• Coupled | 13 ft 6 in (4,115 mm) |
• Trailing | 4 ft 6 in (1,372 mm) |
• Tender | 24 ft 7 1⁄4 in (7,499 mm) |
• Tender bogie | 8 ft 8 in (2,642 mm) |
Length: |
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• Over couplers | 74 ft 9 1⁄4 in (22,790 mm) |
Height | 12 ft 10 7⁄8 in (3,934 mm) |
Frame type | Cast |
Axle load | 11 LT 10 cwt (11,680 kg) |
• Leading | 8 LT (8,128 kg) |
• 1st coupled | 11 LT (11,180 kg) |
• 2nd coupled | 11 LT 10 cwt (11,680 kg) |
• 3rd coupled | 11 LT 9 cwt (11,630 kg) |
• 4th coupled | 11 LT 5 cwt (11,430 kg) |
• Trailing | 10 LT 2 cwt (10,260 kg) leading 9 LT 12 cwt (9,754 kg) trailing |
• Tender bogie |
Bogie 1: 28 LT 1 cwt (28,500 kg) Bogie 2: 28 LT 10 cwt (28,960 kg) |
• Tender axle | 9 LT 10 cwt (9,652 kg) |
Adhesive weight | 45 LT 4 cwt (45,930 kg) |
Loco weight | 72 LT 18 cwt (74,070 kg) |
Tender weight | 56 LT 11 cwt (57,460 kg) |
Total weight | 129 LT 9 cwt (131,500 kg) |
Tender type | MY (Buckeye 3-axle bogies) |
Fuel type | Coal |
Fuel capacity | 9 LT (9.1 t) |
Water cap | 4,520 imp gal (20,500 l) |
Firebox type | Round-top |
• Firegrate area | 36 sq ft (3.3 m2) |
Boiler: |
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• Model | Watson Standard no. 1 |
• Pitch | 8 ft (2,438 mm) |
• Diameter | 5 ft (1,524 mm) |
• Tube plates | 17 ft 9 in (5,410 mm) steel 17 ft 8 5⁄8 in (5,401 mm) copper |
• Small tubes | 76: 2 1⁄2 in (64 mm) |
• Large tubes | 24: 5 1⁄2 in (140 mm) |
Boiler pressure | 200 psi (1,379 kPa) |
Safety valve | Pop |
Heating surface | 1,636 sq ft (152.0 m2) |
• Tubes | 1,497 sq ft (139.1 m2) |
• Arch tubes | 16 sq ft (1.5 m2) |
• Firebox | 123 sq ft (11.4 m2) |
Superheater: |
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• Heating area | 380 sq ft (35 m2) |
Cylinders | Two |
Cylinder size | 19 in (483 mm) bore 26 in (660 mm) stroke |
Valve gear | Walschaerts |
Valve type | Piston |
Loco brake | Vacuum |
Couplers | AAR knuckle |
Performance figures | |
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Tractive effort | 27,600 lbf (123 kN) @ 75% |
Career | |
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Operators | South African Railways |
Class | Class 24 |
Number in class | 100 |
Numbers | 3601-3700 |
Delivered | 1949-1950 |
First run | 1949 |
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The South African Railways Class 24 2-8-4 of 1949 was a steam locomotive.
In 1949 and 1950, the South African Railways placed 100 Class 24 branchline steam locomotives with a 2-8-4 Berkshire type wheel arrangement in service.
By the late 1940s, the South African Railways (SAR) still had a comparatively large mileage of 45 pounds per yard (22 kilograms per metre) track. In South West Africa, where most of the locomotive fleet consisted of Classes 6, 7, GC and GCA, there were still hundreds of miles of 4 1⁄4 pounds per yard (2.1 kilograms per metre) track. Considering the increasing age of these locomotives, the options were either to relay these tracks with 60 pounds per yard (30 kilograms per metre) rail or to obtain new light branchline locomotives, suitable for use on the existing track.
The Class 24 2-8-4 Berkshire type branchline steam locomotive was designed by Dr. M.M. Loubser, Chief Mechanical Engineer (CME) of the 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.
One of these locomotives, no. 3675, was the 2,000th locomotive to be built by NBL for the SAR and, to commemorate this milestone, 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.
The Class 24 had a one-piece cast-steel main frame, which was 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.