South African Class 4 4-8-2

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CGR Mountain 4-8-2
South African Class 4 4-8-2
SAR Class 4 no. 1478.jpg
SAR Class 4 no. 1478 at Worcester, c. 1930
Type and origin
Power typeSteam
DesignerCape Government Railways
(H.M. Beatty)
BuilderNorth British Locomotive Company
Serial number19242-19243
ModelCGR 4-8-2
Build date1911
Total produced2
 • Whyte4-8-2 (Mountain)
 • UIC2'D1'n2
Driver2nd coupled axle
Gauge3 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 wheels33 12 in (851 mm) as built
34 in (864 mm) retyred
Wheelbase57 ft 8 38 in (17,586 mm)
 • Engine31 ft 11 in (9,728 mm)
 • Leading6 ft 2 in (1,880 mm)
 • Coupled14 ft 5 in (4,394 mm)
 • Tender16 ft 1 in (4,902 mm)
 • Tender bogie4 ft 7 in (1,397 mm)
Wheel spacing
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)
 • Over couplers65 ft 38 in (19,822 mm)
Height12 ft 10 in (3,912 mm)
Frame typeBar
Axle load15 LT (15,240 kg)
 • Leading11 LT 3 cwt (11,330 kg)
 • 1st coupled14 LT 10 cwt (14,730 kg)
 • 2nd coupled14 LT 15 cwt (14,990 kg)
 • 3rd coupled14 LT 17 cwt (15,090 kg)
 • 4th coupled15 LT (15,240 kg)
 • Tender bogieBogie 1: 21 LT 11 cwt (21,900 kg)
Bogie 2: 21 LT 18 cwt (22,250 kg)
 • Tender axle10 LT 19 cwt (11,130 kg)
Adhesive weight59 LT 2 cwt (60,050 kg)
Loco weight82 LT 2 cwt (83,420 kg)
Tender weight43 LT 9 cwt (44,150 kg)
Total weight125 LT 11 cwt (127,600 kg)
Tender typeXJ (2-axle bogies)
Fuel typeCoal
Fuel capacity6 LT 10 cwt (6.6 t)
Water cap3,500 imp gal (15,900 l)
Firebox typeRound-top, combustion chamber
 • Firegrate area37 sq ft (3.4 m2)
 • Pitch7 ft 6 in (2,286 mm)
 • Diameter5 ft 6 38 in (1,686 mm)
 • Tube plates18 ft (5,486 mm)
 • Small tubes201: 2 14 in (57 mm)
Boiler pressure180 psi (1,241 kPa)
Safety valveRamsbottom (No. 850/1477)
Cole's Pop (No. 851/1478)
Heating surface2,317 sq ft (215.3 m2)
 • Tubes2,131 sq ft (198.0 m2)
 • Firebox186 sq ft (17.3 m2)
Cylinder size20 12 in (521 mm) bore
28 in (711 mm) stroke
Valve gearStephenson
Valve typeMurdoch's D slide
CouplersJohnston link-and-pin
Performance figures
Tractive effort29,420 lbf (130.9 kN) @ 75%
OperatorsCape Government Railways
South African Railways
ClassSAR Class 4
Number in class2
NumbersCGR 850-851
SAR 1477-1478
First run1911
The leading coupled axle had flangeless wheels

The South African Railways Class 4 4-8-2 of 1911 was a steam locomotive from the pre-Union era in the Cape of Good Hope.

In 1911, the Cape Government Railways placed two steam locomotives with a 4-8-2 Mountain type wheel arrangement in service. They were renumbered and designated Class 4 when they were assimilated into the South African Railways a year later.[1][2][3][4]


The first 4-8-2 Mountain type locomotive of the Cape Government Railways (CGR) was designed as a heavy mixed traffic engine at the Salt River shops by H.M. Beatty, the Chief Locomotive Superintendent of the CGR from 1896 to 1910. Two locomotives were built by the North British Locomotive Company (NBL) and delivered in March 1911.[1][4][5]


The locomotives were a further development of the two experimental locomotives which had been placed in service by the CGR in 1906, the CGR Class 9 2-8-2 (SAR Class Experimental 5) and the CGR Class 10 4-8-0 (SAR Class Experimental 6), both built by Kitson and Company.[1][4][5]

H.M. Beatty

The Class 4 locomotives had 4 12 inches (114 millimetres) thick bar frames, Stephenson valve gear with flat "D" slide valves arranged above the cylinders, and used saturated steam. The boiler was equipped with a combustion chamber which was carried forward 2 feet (610 millimetres) from the firebox into the boiler barrel, of which the diameter was increased at the hind course to suit. This reduced the distance between the tube plates to 18 feet (5,486 millimetres) and made them excellent steamers.[1][2][4]

They were numbered 850 and 851 in the CGR numbering sequence, but were not designated a classification. The two engines were not identical, no. 850 being equipped with the usual Ramsbottom safety valves while no. 851 had Cole’s muffled type Pop safety valves, both set to open at 180 pounds per square inch (1,241 kilopascals) boiler pressure. They were delivered with Type XJ tenders with a 6 long tons 10 hundredweight (6.6 tonnes) coal and a 3,500 imperial gallons (15,900 litres) water capacity.[2][4][6][7]

South African Railways[edit]

Railway network of the Cape Government Railways in 1910, upon the establishment of the Union of South Africa and the South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (CGR, Natal Government Railways and Central South African Railways) were united under a single administration to control and administer the railways, ports and harbours of the Union. Although the South African Railways and Harbours came into existence in 1910, with Sir William Hoy appointed as its first General Manager, the actual classification and renum­bering of all the rolling stock of the three constituent railways were only implemented with effect from 1 January 1912.[3][8]

In 1912, these two locomotives were renumbered to 1477 and 1478 and designated Class 4 on the SAR.[3][4][6]


Both locomotives were placed in service in the Karoo, working between Touws River and Beaufort West. In their later years they were stationed at Worcester, from where they were used extensively on and around the Cape Western system’s mainline, working pick-up goods trains to De Doorns in the Hex River valley and on the Mosselbaai line via Robertson.[1][4]

They were withdrawn from service by 1938.[4]


The main picture shows SAR no. 1478 at Worcester, c. 1930, with Cole's Pop safety valves.


  1. ^ a b c d e Holland, D. F. (1972). Steam Locomotives of the South African Railways. 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 12–13, 137. ISBN 978-0-7153-5427-8.
  2. ^ a b c Espitalier, T.J.; Day, W.A.J. (1945). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways. South African Railways and Harbours Magazine, April 1945. p. 275.
  3. ^ a b c Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 8, 12, 15, 46 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  4. ^ a b c d e f g h Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 38–39. ISBN 0869772112.
  5. ^ a b Durrant, A. E. (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. p. 13. ISBN 0715386387.
  6. ^ a b Holland, D.F. (1971). Steam Locomotives of the South African Railways. 1: 1859–1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 72–75. ISBN 978-0-7153-5382-0.
  7. ^ North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  8. ^ The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.