South African Class 4A 4-8-2

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

300px 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 axle 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia Coupled dia 54 in (1,372 mm) Trailing dia 33 in (838 mm) Tender wheels as built 34 in (864 mm) retyred Wheelbase  • 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 (Assymetrical) 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 Height ♠ 12 ft 10 in (3,912 mm) ♥ Axle load ♠ ♥  • Leading ♠ ♥  • 1st coupled ♠ ♥  • 2nd coupled ♠ ♥  • 3rd coupled ♠ ♥  • 4th coupled ♠ ♥  • Trailing ♠ ♥  • Tender bogie Bogie 1: Bogie 2:  • Tender axle Adhesive weight ♠ ♥ Loco weight ♠ ♥ Tender weight w/o Loco & tender weight ♠ w/o ♥ 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 Boiler ♥ Watson Standard no. 2  • Pitch ♠ 7 ft 6 in (2,286 mm) ♥ 8 ft (2,438 mm)  • Diameter ♠ ♥  • Tube plates ♠ 18 ft 3 in (5,563 mm) ♥♣ 19 ft 4 in (5,893 mm) ♥♦  • Small tubes ♠ 144: ♥ 81:  • large tubes ♠ 22: ♥ 30:  • Firebox type Round-top Boiler pressure 180 psi (1,241 kPa) Safety valve Cole's Pop Firegrate area ♠♥ 37 sq ft (3.4 m2) 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 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African Railways Class Class 4A, Class 4AR Number in class 10 Numbers 1551-1560 Delivered 1913-1914 First run 1913 Withdrawn 1974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.

Manufacturer

File:H.M. Beatty.jpg

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.

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 .

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.

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.

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 to .

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.

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.

File:Class 4AR 1554 (4-8-2).jpg

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.

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.

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

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.

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.

• SAR Class 4AR (4-8-2).jpg

  Reboilered Class 4AR with the rectangular regulator cover and a Watson cab with its slanted front, c. 1970

• Class 4A (4-8-2) a.jpg

  Class 4A on a local between Langlaagte and Mayfair, c. 1930

• Class 4A (4-8-2) b.jpg

  Class 4A at Driehoek at Simmer & Jack’s mine with a passenger train from Breyten, c. 1930

• SAR Class 4AR 1554 (4-8-2).jpg

  Class 4AR no. 1554 with a Watson cab, but without the rectangular regulator cover, c. 1970