South African Class Exp 2 2-8-0

South African Class Exp 2 2-8-0 ex CGR Tandem Compound 2-8-0
CGR Tandem Compound Consolidation no. 804 SAR Class Experimental 2 no. 908
Type and origin
Power type	Steam
Designer	Cape Government Railways
Builder	American Locomotive Company
Serial number	26694 ^[1]
Model	CGR Tandem Compound
Build date	1902
Total produced	1
Specifications
Configuration	2-8-0 "Consolidation"
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Leading wheel diameter	28.5 in (724 mm)
Driver diameter	48 in (1,220 mm)
Wheelbase	Total: 46 ft 5 in (14.148 m) Engine: 14 ft 6 in (4.420 m) coupled 22 ft 2 in (6.756 m) total Tender: 5 ft (1.524 m) bogie 14 ft 5 in (4.394 m) total
Length	53 ft 8 in (16.358 m)
Height	12 ft 10 in (3.912 m)
Axle load	14 long tons (14.2 t) on 1st driver
Weight on drivers	51.15 long tons (52.0 t)
Locomotive weight	57.8 long tons (58.7 t)
Tender weight	34 long tons (34.5 t)
Locomotive and tender combined weight	91.8 long tons (93.3 t)
Tender type	2 axle bogies Wheels 33.5 in (851 mm) diameter
Fuel type	Coal
Fuel capacity	6 long tons (6.1 t)
Water capacity	3,080 imp gal (14,000 l)
Boiler	4 ft 11 in (1.499 m) inside diameter 12 ft 5.625 in (3.800 m) inside length 7 ft 1 in (2.159 m) pitch
Boiler pressure	200 psi (1,380 kPa)
Firegrate area	20 sq ft (1.858 m²)
Heating surface: – Tubes	196 tubes 2 in (50.8 mm) diameter 1,279.6 sq ft (118.879 m²)
– Firebox	129.8 sq ft (12.059 m²)
– Total	1,409.4 sq ft (130.938 m²)
Cylinders	Four
High-pressure cylinder size	13 in (330 mm) bore 26 in (660 mm) stroke
Low-pressure cylinder size	23 in (584 mm) bore 26 in (660 mm) stroke
Valve gear	Stephenson
Performance figures
Tractive effort	26,400 lbf (117 kN) at 75% pressure
Career
Operator(s)	Cape Government Railways South African Railways
Class	CGR Tandem Compound SAR Class Exp 2 ^[1]
Number in class	1
Number(s)	CGR 804, SAR 908 ^[2]^[3]
Delivered	1902
First run	1902
Withdrawn	1916

The South African Class Experimental 2 2-8-0 of 1902 was a South African steam locomotive from the pre-Union era in the Cape Colony.

In 1902 the Cape Government Railways placed a single experimental 2-8-0 Consolidation type tandem compound steam locomotive in service, based on its Schenectady-built 8th Class of 1901. In 1912, when the locomotive was assimilated into the South African Railways, it was renumbered and classified as Class Experimental 2.^[1]^[2]^[4]

Manufacturer

In the first few years of the twentieth century H.M. Beatty, Locomotive Superintendent of the Cape Government Railways (CGR), experimented with various forms of compound steam locomotives. The first of these locomotives was delivered by the American Locomotive Company (ALCO) in 1902. It was based on the CGR’s Schenectady-built 8th Class of the previous year, later the Class 8X, and was numbered 804. It was not classified by the CGR and was simply referred to as the Tandem Compound.^[1]^[4]

Compound expansion

Compound locomotive

In a compound locomotive steam is expanded in phases. After being expanded in a high pressure cylinder and having then lost pressure and given up part of its heat, it is exhausted into a larger volume low pressure cylinder for secondary expansion, after which it is exhausted through the smokebox. By comparison, in the more usual arrangement of simple expansion (simplex), steam is expanded just once in any one cylinder before being exhausted through the smokebox.^[5]

Tandem compound

The tandem compound locomotive first appeared on the American Erie Railroad in 1867. In a tandem compound engine each pair of high and low pressure cylinders drove a common crosshead, connecting rod and crank. The high pressure cylinders were bolted onto the fronts of the low pressure cylinders, which were each cast integrally with one half of the smokebox saddle. The hollow piston valves were mounted on the same valve spindle in a common steam chest, with the high pressure valves arranged for inside admission and the low pressure valves for outside admission.^[1]^[4]^[6]

The high-pressure cylinders were 13 inches (330 millimetres) in diameter and the low-pressure cylinders 23 inches (584 millimetres), with a common stroke of 26 inches (660 millimetres). The steam was admitted to the same side of each piston simultaneously by means of an intricate system of crossed ports in the high pressure cylinder casting to convey its spent steam to the low pressure cylinder, from where it was then exhausted after use.^[1]^[4]

Performance

Considerable trouble was experienced with the tandem arrangement, since the piston rod packing between the high and low pressure cylinders could not be inspected or serviced without removing the high pressure cylinders. In addition, as a result of high levels of condensation, the low pressure cylinders were inefficient since the drain cocks had to be opened frequently enough to detract from the locomotive’s otherwise good performance.^[1]

Modification

Beatty was apparently not greatly impressed with the tandem compound and it was not long before he had the compound cylinders removed and the locomotive converted to a simple expansion engine.^[1]

Service

The locomotive was placed in service on the lower section of the Cape mainline, where it was used with limited success until it was converted to simplex steaming.^[4]

The Union of South Africa was established on 31 May 1910, in terms of the South Africa Act. One of the clauses in the Act required that the three Colonial Government railways, the CGR, the Natal Government Railways and the Central South African Railways, also be united under one single administration to control and administer the railways, ports and harbours of the Union. While the South African Railways (SAR) came into existence in 1910, the actual classification and renumbering of all the rolling stock of the three constituent railways required careful planning and was only implemented with effect from 1 January 1912.^[2]^[7]

In 1912 the locomotive was classified as Class Experimental 2 and renumbered to 908 on the SAR. It remained in SAR service only until 1916, when it was withdrawn.^[2]^[4]

References

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South African Class Exp 2 (2-8-0)

↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 67–68. ISBN 978-0-7153-5382-0.
↑ 2.0 2.1 2.2 2.3 Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 9, 12, 15, 36 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
↑ Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. p. 140. ISBN 978-0-7153-5427-8.
↑ 4.0 4.1 4.2 4.3 4.4 4.5 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 82. ISBN 0869772112.
↑ Compounding Steam Locomotives
↑ Tandem Compounding Locomotives
↑ The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.

Locomotives of South Africa

Steam

Brunel gauge	HBEL 0-4-0 HBTB 0-4-0T HBTB 0-4-0WT HBTB 0-4-0ST

Broad gauge	CGR Aid CGR Blackie CGR 0-4-2 CGR 2-4-0T NRC Durban NRC Natal NRC Perseverance

Cape gauge Tank	CGR Coffee Pot CGR 040 1873 CGR 040 1874 CGR 060 1876 CGR 060 1902 CGR 260 1900 CGR 260 1902 CGR 1st 040 1875 CGR 1st 440 1875 CGR 1st 040 1876 CGR 1st 260 1876 CGR 2nd 1882 CGR 3rd 1900 CGR RM CSAR C CSAR E CSAR Rack CSAR RM Dbn Congella Dbn Edward Innes Dbn John Milne Dbn Sir Albert HBPE 040 Kowie 060 Kowie 440 M&S 462 NGR Dbn & Pmb NGR I 262 NGR K 040 NGR K 060 NGR K 260 NZASM 10T NZASM 14T NZASM 18T NZASM 19T NZASM 32T NZASM 40T PPR 26T PPR 35T SAR RM SAR 0-4-0ST SAR 040 69 SAR A SAR B SAR C SAR C1 SAR C2 SAR D SAR E SAR F SAR G SAR H SAR H1 SAR H2 SAR J SAR K SWA 2-8-0T

Cape gauge Tender	CGR 1st 260 1876 BP CGR 1st 260 1876 K CGR 1st 260 1879 CGR 1st 440 1879 CGR 1st 1881 CGR 1st 1891 CGR 2nd 1875 CGR 3rd 1883 CGR 3rd 1884 CGR 3rd 1889 CGR 3rd 1898 CGR 3rd 1901 CGR 3rd 1903 CGR 4th 1880 CGR 4th 1882 CGR 4th 1884 CGR 4th 1897 CGR 5th 1890 CGR 5th 1891 NGR Havelock NGR I 260 Exp-1 Exp-2 Exp-3 Exp-4 Exp-5 Exp-6 SAR S SAR S1 SAR S2 SAR 1 SAR 1A SAR 1B SAR 2 SAR 2C SAR 3 SAR 3A SAR 3B SAR 4 SAR 4A SAR 5 SAR 5A SAR 5B SAR 6 SAR 6A SAR 6B SAR 6C SAR 6D SAR 6E SAR 6F SAR 6G SAR 6H SAR 6J SAR 6K SAR 6L SAR 6Y SAR 6Z SAR 7 SAR 7A SAR 7B SAR 7C SAR 7D SAR 7E SAR 7F SAR 8 SAR 8A SAR 8B SAR 8C SAR 8D SAR 8E SAR 8F SAR 8X SAR 8Y SAR 8Z SAR 9 SAR 10 SAR 10A SAR 10B SAR 10C SAR 10D SAR 11 SAR 12 SAR 12A SAR 12B SAR 13 SAR 14 SAR 14A SAR 14B SAR 14C SAR 15 SAR 15A SAR 15B SAR 15C SAR 15CA SAR 15E SAR 15F SAR 16 SAR 16A SAR 16B SAR 16C SAR 16D SAR 16DA SAR 16E SAR 17 SAR 18 SAR 19 SAR 19A SAR 19B SAR 19C SAR 19D SAR 20 SAR 21 SAR 23 SAR 24 SAR 25 SAR 25NC SAR 26 SWA 2-8-0

Cape gauge Articulated	CGR Fairlie CGR Kitson-Meyer SAR FC SAR FD SAR GA SAR GB SAR GC SAR GCA SAR GD SAR GDA SAR GE SAR GEA SAR GF SAR GG SAR GH SAR GK SAR GL SAR GM SAR GMA SAR GO SAR HF SAR KM SAR MA SAR MB SAR MC SAR MC1 SAR MD SAR ME SAR MF SAR MG SAR MH SAR MJ SAR MJ1 SAR U

2ft 6in gauge	CCC 1871 CCC Britannia CCC Caledonia CCC Clara CCC Condenser CCC Scotia NCC Pioneer

2ft & 600mm gauges	ACR NG-G16A CGR NG 060 CGR NG 462 CGR A CGR C NGR N SAR 040 1899 SAR NG1 SAR NG2 SAR NG3 SAR NG4 SAR NG5 SAR NG6 SAR NG7 SAR NG8 SAR NG9 SAR NG10 SAR NG-G11 SAR NG-G12 SAR NG-G13 SAR NG-G14 SAR NG15 SAR NG-G16 SWA Ha SWA Hb SWA Hc SWA Hd SWA Jung SWA Zwillinge

Diesel

-electric	SAR DS SAR DS1 SAR 31-000 SAR 32-000 SAR 32-200 SAR 33-000 SAR 33-200 SAR 33-400 SAR 34-000 SAR 34-200 SAR 34-400 SAR 34-500 SAR 34-600 SAR 34-800 SAR 34-900 SAR 35-000 SAR 35-200 SAR 35-400 SAR 35-600 SAR 36-000 SAR 36-200 SAR 37-000 SN 39-000 TFR 39-200 TFR 43-000 SAR 91-000 Afro4000

-hydraulic	SAR 61-000

Electro-diesel

SN 38-000

Electric