South African Class 24 2-8-4
3655 City of Cape Town leaving Monument station, 8 August 2010
Type and origin 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 Configuration: ​  • Whyte 2-8-4 (Berkshire)  • UIC 1′D2′h2 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: ​  • 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  • Grate area 36 sq ft (3.3 m2) Boiler: ​  • 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 Ross-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: ​  • 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 Tractive effort 27,600 lbf (123 kN) @ 75%
Career Operators South African Railways Class Class 24 Number in class 100 Numbers 3601-3700 Delivered 1949-1950 First run 1949 Withdrawn 1980s

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

In 1949 and 1950, the South African Railways placed 100 Class 24 branch line steam locomotives with a 2-8-4 Berkshire type wheel arrangement in service.^[1][2][3]

Manufacturer

No. 3632 Tootsie at George, Cape Province, 29 September 1989

Preserved no. 3693 at Oudtshoorn, Cape Province, c. 1991. It was scrapped in 2016.

No. 3654 staged at Beaconsfield, Kimberley, 17 September 2009

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 40+1⁄4 pounds per yard (20.0 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 branch line locomotives suitable for use on the existing track.^[2]

The Class 24 2-8-4 Berkshire type branch line 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 100 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][2][4][5]

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 Bartholomew Diaz after the Portuguese navigator Bartolomeu Dias 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][5]

Characteristics

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.^[1][5]

They were built with Watson Standard no. 1 boilers, while their double hopper type ashpans were specially designed to clear the four-wheeled trailing bogies. Their specially designed Type MY tenders were similar in appearance to the Type MX and the North American Vanderbilt type tenders, with cylindrical water tanks. The tenders rode on three-axle Buckeye bogies to reduce the axle load and, along with the Type MX, became commonly known as Torpedo tenders.^{[1][2][3][6][7]}

The piston valves were actuated by Walschaerts valve gear and the standard SAR type steam reversing gear was arranged on the right-hand side. The engine and tender were both equipped with vacuum brakes and the engine's two 21 inches (533 millimetres) diameter vacuum cylinders were arranged outside the engine's frame and under the running boards, one on either side. The valve gear, brake gear and coupled wheel hubs were soft grease lubricated, while the bronze axle boxes had hard grease lubrication. The leading and trailing bogies were fitted with roller bearing axle boxes while the tender's bogies used plain bearings.^[2]

Service

The Class 24 was built to replace the old Classes 6, 7 and 8 locomotives in branch line service on light rail. When they were introduced, an elaborate programme was drawn up to show on which systems and on what sections they were to be employed.^[1][8]

• 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 Soekmekaar-Komatipoort, Barberton-Kaapmuiden, Middelburg-Stoffberg, Brits-Beestekraal and Zebediela-Naboomspruit sections.
• The South West Africa System, on the De Aar-Karasburg and Keetmanshoop-Windhoek sections.

Most of them went to the South West Africa System, where 55 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 1961, when strengthening of the track and the complete dieselisation of the South West Africa System made them available to be employed elsewhere.^[1][3][5]

Other branch lines to be served by the Class 24 include Breyten to Lothair, Nylstroom to Vaalwater, Port Elizabeth to Alexandra and George to Knysna. 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. Some eventually also worked on the Selati line in the Transvaal Lowveld. Heavy overhauls were done at Bloemfontein. The only province where they were unknown was Natal.^[1][3][5][8]

The Calvinia and Sakrivier branches had been worked almost exclusively by Class 19C locomotives from about 1950, but from 1951 two Class 24s were also allocated to Beaufort West and sub-shedded at Hutchinson. After February 1963, this was reduced to one Class 24 locomotive until long after the branch was dieselised c. 1960, using Class 32-000 locomotives based at De Aar. For some six months in the latter half of 1969, the Calvinia and Sakrivier branches reverted to steam-only operation when there was a huge surge in ore traffic that required the drafting in of more Class 32-000 locomotives to the Port Elizabeth mainline. A pair of Class 24 locomotives temporarily worked those branches in 1969 and 1970 as relief engines during the diesel-electric locomotive shortage.^[9]

Preservation

The following is a list of 24 class that have survived into preservation. January 1, 2019

References

External links

Wikimedia Commons has media related to South African Class 24 (2-8-4).

External videos

South African Steam: Pretoria area - Rovos Rail, THF Museum and 3664 rollover (16 March 1997) The video features a few trains on the same day in the Pretoria area. First we see Friends of the Rail's Class 24 no. 3664 heading out on the Hercules-Magaliesburg branch on a charter train. Whilst out at Meerhof, word came through that Rovos Rail were triple-heading their Pretoria train behind Class 6 no. 439 and Class 19D nos. 2701 and 2702, so I rushed down to Irene to see that. Later in the afternoon, one of the last THF Museum-run Magaliesburg trains departed with Class 15F no. 3040. Following that, we headed to Magaliesburg to follow the Friends of the Rail train back to Pretoria. Sadly, no. 3664 had not made it to Magaliesburg, having derailed and rolled over at Hekpoort. The remaining scenes feature the recovery crew's efforts to set no. 3664 upright again. (Time 14:51)

External videos

South African Steam: Class 24 No. 3664 - The Phoenix Rises (16 March to 31 May 1997) After her derailment and rollover at Hekpoort on 16 March 1997, Class 24 no. 3664 was recovered and returned to her home depot at Capital Park. Repairs began in earnest immediately. The tender, cab sides, cab roof, valve gear, wheels, bearings, cowcatcher, cylinder cladding and much more required repair or renewal. In just two months, 3664 was repaired and performed a line trial on a revenue freight train, before returning to the rails on a public train on 31 May 1997. (Time 12:26)

External videos
South African Steam: 3664 Restoration in the news (1997) SABC News story, covering the fall and rise of Class 24 no. 3664. (Time 1:17)

External videos
South African Steam: Steam to Cullinan - 24 3664 (28 June 1997) Class 24 no. 3664 on a return trip to Cullinan (Time 9:53)