South African Class MF 2-6-6-2

CSAR Mallet 2-6-6-2 Superheated
South African Class MF 2-6-6-2

SAR no. 1620, ex CSAR no. 1016, c. 1920

Type and origin
♠ Locomotive numbers 1619-1627 ♥ Locomotive numbers 1629-1633
Power type	Steam
Designer	American Locomotive Company
Builder	American Locomotive Company
Serial number	49115-49123, 50039-50043
Model	CSAR Mallet
Build date	1910-1911
Total produced	14

Specifications
Configuration	2-6-6-2 (Prairie Mallet)
Driver	3rd & 6th coupled axles
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Leading dia.	28 ¹⁄₂ in (724 mm)
Coupled dia.	46 in (1,168 mm)
Trailing dia.	28 ¹⁄₂ in (724 mm)
Tender wheels	♠ 34 in (864 mm) ♥ 30 in (762 mm)
Wheelbase	♠ 65 ft 6 in (19,964 mm)
• Engine	40 ft 3 in (12,268 mm)
• Coupled	8 ft 4 in (2,540 mm) per unit
• Tender	♠ 17 ft 11 in (5,461 mm) ♥ 17 ft 10 in (5,436 mm)
• Tender bogie	♠ 4 ft 7 in (1,397 mm) ♥ 5 ft 10 in (1,778 mm)
Length:
• Over couplers	♠ 73 ft 7 ¹⁄₄ in (22,435 mm)
Height	12 ft 10 ³⁄₈ in (3,921 mm)
Frame type	Bar
Axle load	15 LT 3 cwt (15,390 kg)
• Leading	7 LT 12 cwt (7,722 kg)
• 1st coupled	14 LT 14 cwt (14,940 kg)
• 2nd coupled	14 LT 3 cwt (14,380 kg)
• 3rd coupled	13 LT 19 cwt (14,170 kg)
• 4th coupled	15 LT 3 cwt (15,390 kg)
• 5th coupled	14 LT 15 cwt (14,990 kg)
• 6th coupled	14 LT 15 cwt (14,990 kg)
• Trailing	7 LT 12 cwt (7,722 kg)
• Tender bogie	♠ 27 LT 12 cwt (28,040 kg) each ♥ 25 LT 10 cwt (25,910 kg) av.
• Tender axle	♠ 13 LT 16 cwt (14,020 kg) ♥ 12 LT 15 cwt (12,950 kg) av.
Adhesive weight	87 LT 9 cwt (88,850 kg)
Loco weight	102 LT 13 cwt (104,300 kg)
Tender weight	♠ 55 LT 4 cwt (56,090 kg) ♥ 51 LT (51,820 kg)
Total weight	♠ 157 LT 17 cwt (160,400 kg) ♥ 153 LT 13 cwt (156,100 kg)
Tender type	♠ XS (2-axle bogie) ♥ XM4 (2-axle bogie)
Fuel type	Coal
Fuel capacity	♠♥ 10 LT (10.2 t)
Water cap	♠ 5,000 imp gal (22,700 l) ♥ 4,000 imp gal (18,200 l)
Firebox type	Round-top
• Firegrate area	49.5 sq ft (4.60 m²)
Boiler:
• Pitch	7 ft 9 in (2,362 mm)
• Diameter	6 ft ¹⁄₈ in (1,832 mm)
• Tube plates	19 ft 10 ¹⁄₈ in (6,048 mm)
• Small tubes	151: 2 ¹⁄₄ in (57 mm)
• Large tubes	25: 5 ³⁄₈ in (137 mm)
Boiler pressure	200 psi (1,379 kPa)
Safety valve	Ramsbottom
Heating surface	2,615.6 sq ft (243.00 m²)
• Tubes	2,459.6 sq ft (228.50 m²)
• Firebox	156 sq ft (14.5 m²)
Superheater:
• Type	Schmidt
• Heating area	559 sq ft (51.9 m²)
Cylinders	Four
High-pressure cylinder	18 in (457 mm) bore 26 in (660 mm) stroke
Low-pressure cylinder	28 ¹⁄₂ in (724 mm) bore 26 in (660 mm) stroke
Valve gear	Walschaerts
Couplers	Bell link-and-pin

Performance figures
Tractive effort	45,900 lbf (204 kN) @ 50%

Career
Operators	Central South African Railways South African Railways
Class	Class MF
Number in class	14
Numbers	CSAR 1015-1023 SAR 1619-1627, 1629-1633
Delivered	1911
First run	1911
Withdrawn	1939

The South African Railways Class MF 2-6-6-2 of 1911 was a steam locomotive from the pre-Union era in the Transvaal.

In 1911, the Central South African Railways placed nine Mallet articulated compound steam locomotives with a 2-6-6-2 wheel arrangement in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and designated Class MF. Five more of these locomotives were delivered in November 1911 and were numbered directly onto the South African Railways roster.^[1]^[2]^[3]^[4]

Manufacturer

Nine Mallet articulated compound steam locomotives, which were delivered to the Central South African Railways (CSAR) in 1911, were built by the American Locomotive Company (ALCO) in 1910 and 1911. They were erected at the Durban workshops in March 1911 and were very similar to the experimental Class MD which had been delivered in 1910, except that the new locomotives were equipped with Schmidt superheaters. The engines had Walschaerts valve gear and Type XS tenders, with a coal capacity of 10 long tons (10.2 tonnes) and a water capacity of 5,000 imperial gallons (22,700 litres). They were numbered in the range from 1015 to 1023.^[1]^[2]^[3]^[4]^[5]

Compound expansion

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.^[1]^[6]

In the compound Mallet locomotive, the rear set of coupled wheels are driven by the smaller high-pressure cylinders, which are fed steam from the steam dome, via the superheater. Their spent steam is then fed to the larger low-pressure cylinders, which drive the front set of coupled wheels.^[1]^[3]

Characteristics

The most noticeable external difference from the experimental Class MD engine was the arrangement of the main steam pipes, necessitated by the superheater. Instead of being led vertically down from the dome directly to the high-pressure cylinders, an internal pipe was taken from the regulator valve in the dome to the superheater in the smokebox, from where it was brought back to the high-pressure cylinders by external steam pipes, arranged under the running boards.^[2]

South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (Cape Government Railways, Natal Government Railways and CSAR) 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 required careful planning and was only implemented with effect from 1 January 1912.^[4]^[7]

In 1912, these locomotives were renumbered in the range from 1619 to 1627 and designated Class MF on the South African Railways (SAR). Five more of the type had been delivered from ALCO in November 1911, but these were numbered in the range from 1629 to 1633, directly onto the SAR roster, marking the introduction of the SAR renumbering scheme under the Union programme. These locomotives were delivered with smaller Type XM4 tenders, with the same coal capacity as the Type XS tenders of the first nine engines, but a smaller water capacity of 4,000 imperial gallons (18,200 litres).^[1]^[3]^[4]^[8]

The new locomotives were erected in the workshops in Pretoria, rather than Durban. The erection of engines away from ports was an innovation which was probably the outcome of experience gained with the Class MD, which had been erected at Durban. While the locomotive was brought to the Transvaal, difficulty was experienced at Drummond and Laing's Nek, where the drain angles on the cab roof struck the sides of the tunnels.^[8]

Service

The Class MF joined the experimental Class MD on the coal traffic line between Witbank and Germiston. They were acquired to improve the traffic flow on this line, with its ruling gradient of one in one hundred (1%), where the increase of traffic and the resultant congestion was causing considerable delays en route, which led to excessive hours of duty being imposed on crews. When the Mallets replaced the existing Class 11 locomotives on this line, train loads could be increased from 900 long tons (914 tonnes) to 1,600 long tons (1,626 tonnes).^[1]^[3]

The Mallets proved to be capable of handling the heavy coal loads. In May 1914, Class MF no. 1620 was used in a test run from Witbank to Germiston, hauling fifty-five bogie wagons with an all-up weight of 1,626 long tons (1,652 tonnes). The 80 miles (129 kilometres) journey was accomplished in seven hours, which included several stops.^[1]^[8]

Modification to simplex

In 1923, engine no. 1620 was converted to a simplex locomotive in the Salvokop shops in Pretoria. Five more, numbers 1621 to 1623, 1631 and 1632, were also converted to simplex locomotives in 1925. Three of these, numbers 1620, 1631 and 1632, were then transferred to East London, where more powerful locomotives were needed, since the mainline had a heavy gradient of one in forty (2½%) which started right at the end of the East London departing platform, making it an extremely difficult section. They appear to have not been up to the task in the Eastern Cape, however, since by 1926 they were observed there, staged out of service.^[1]^[2]^[3]^[8]

They were all withdrawn from service and scrapped by 1939.^[3]

Illustration

The pictures serve to illustrate the compound and simplex versions of the Class MF.

SAR no. 1620, ex CSAR no. 1016 as compound engine, c. 1920
SAR no. 1623 as simplex engine, c. 1930
SAR no. 1627, ex CSAR no. 1023 as compound engine, c. 1912

References

1 2 3 4 5 6 7 8 Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 16–19, 140. ISBN 978-0-7153-5427-8.
1 2 3 4 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. pp. 275-276.
1 2 3 4 5 6 7 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 86–87. ISBN 0869772112.
1 2 3 4 Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 9, 12, 16, 47 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
↑ Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 54, 56. ISBN 978-0-7153-5382-0.
↑ Compounding Steam Engines
↑ The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.
1 2 3 4 Espitalier, T.J.; Day, W.A.J. (1945). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued). South African Railways and Harbours Magazine, May 1945. p. 347.

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Locomotives of the Central South African Railways

3' 6" gauge	CSAR 0-6-0ST 1896 CSAR 4-6-0T 1887 CSAR Class 6-L1 CSAR Class 6-L2 CSAR Class 6-L3 CSAR Class 7 CSAR Class 8-L1 CSAR Class 8-L2 CSAR Class 8-L3 CSAR Class 9 CSAR Class 10 1904 CSAR Class 10 1910 CSAR Class 10-2 Saturated CSAR Class 10-2 Superheated CSAR Class 10-C CSAR Class 11 CSAR Class B 0-6-4T CSAR Class C 2-8-4T CSAR Class D CSAR Class E 4-8-0TT CSAR Class E 4-8-2T CSAR Class E 4-10-2T CSAR Class F CSAR Class M CSAR Mallet Saturated CSAR Mallet Stoker CSAR Mallet Superheated CSAR Rack 4-6-4RT CSAR Railmotor IMR 0-6-0ST 1896 IMR 4-6-0T 1887 IMR 46 Tonner 0-6-4T IMR 55 Tonner 2-6-4T IMR 7th Class 4-8-0 IMR 8th Class 4-8-0 IMR Reid Tenwheeler 4-10-2T IMR Western Australian 2-8-4T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner NZASM 46 Tonner OVGS 1st Class 4-4-0TT OVGS 2nd Class 2-6-0 OVGS 2nd Class 2-6-0ST OVGS 3rd Class 4-4-0 OVGS 4th Class G 4-6-0 OVGS 5th Class K 4-6-0 1890 OVGS 5th Class K 4-6-0 1891 OVGS 6th Class L 4-6-0 OVGS 6th Class L2 4-6-0 OVGS 6th Class L3 4-6-0 PPR 0-4-0ST Natal PPR 26 Tonner PPR 35 Tonner Portuguese PPR 55 Tonner

2' gauge	CSAR Pankop

List of South African locomotive classes South African locomotive history

Locomotives of South Africa

Steam

7' ¼" gauge	East London 0-4-0VB Table Bay 0-4-0ST Table Bay 0-4-0T Table Bay 0-4-0WT

4' 8½" gauge	Cape 0-4-0T Blackie Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid Natal 0-4-0ST Durban Natal 0-4-0WT Natal Natal 4-4-0T Perseverance

3' 6" gauge Tank engines	CGR 0-4-0ST 1873 CGR 0-4-0ST 1874 CGR 0-4-0ST 1881 CGR 0-4-0ST 1881 Coffee Pot CGR 0-6-0ST CGR 0-6-0T CGR 2-6-0ST 1900 CGR 2-6-0ST 1902 CGR 1st Class 0-4-0ST 1875 CGR 1st Class 0-4-0ST 1876 CGR 1st Class 2-6-0ST CGR 1st Class 4-4-0T CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T CGR Railmotor CSAR Class C CSAR Class E CSAR Rack 4-6-4RT CSAR Railmotor Durban's Congella Durban's Edward Innes Durban's John Milne Durban's Sir Albert Port Elizabeth 0-4-0ST Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NGR 2-6-0T Durban & Pietermaritzburg NGR Class I 2-6-2T NGR Class K 0-4-0ST NGR Class K 0-6-0ST NGR Class K 2-6-0T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner PPR 26 Tonner PPR 35 Tonner Portuguese SAR Class A SAR Class B SAR Class C SAR Class C1 SAR Class C2 SAR Class D SAR Class E SAR Class F SAR Class G SAR Class H SAR Class H1 SAR Class H2 SAR Class J SAR Class K SAR Railmotor SAR Dock 0-4-0ST SAR Dock 0-4-0T SWA 2-8-0T

3' 6" gauge Tender engines	CGR 1st Class 2-6-0 1876 BP CGR 1st Class 2-6-0 1876 Kitson CGR 1st Class 2-6-0 1879 CGR 1st Class 2-6-0 1891 CGR 1st Class 4-4-0 CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 3rd Class 4-4-0 1883 CGR 3rd Class 4-4-0 1884 CGR 3rd Class 4-4-0 1889 CGR 3rd Class 4-4-0 1898 CGR 3rd Class 4-4-0 1901 CGR 3rd Class 4-4-0 1903 CGR 4th Class 4-4-2 CGR 4th Class 4-6-0TT 1880 CGR 4th Class 4-6-0TT 1882 CGR 4th Class 4-6-0TT 1882 Joy CGR 4th Class 4-6-0TT 1884 CGR 5th Class 4-6-0 1890 CGR 5th Class 4-6-0 1891 NGR Havelock NGR Class I SAR Class Exp 1 SAR Class Exp 2 SAR Class Exp 3 SAR Class Exp 4 SAR Class Exp 5 SAR Class Exp 6 SAR Class S SAR Class S1 SAR Class S2 SAR Class 1 SAR Class 1A SAR Class 1B SAR Class 2 SAR Class 2C SAR Class 3 SAR Class 3A SAR Class 3B SAR Class 4 SAR Class 4A SAR Class 5 SAR Class 5A SAR Class 5B SAR Class 6 SAR Class 6A SAR Class 6B SAR Class 6C SAR Class 6D SAR Class 6E SAR Class 6F SAR Class 6G SAR Class 6H SAR Class 6J SAR Class 6K SAR Class 6L SAR Class 6Y SAR Class 6Z SAR Class 7 SAR Class 7A SAR Class 7B SAR Class 7C SAR Class 7D SAR Class 7E SAR Class 7F SAR Class 8 SAR Class 8A SAR Class 8B SAR Class 8C SAR Class 8D SAR Class 8E SAR Class 8F SAR Class 8R SAR Class 8X SAR Class 8Y SAR Class 8Z SAR Class 9 SAR Class 10 SAR Class 10A SAR Class 10B SAR Class 10C SAR Class 10D SAR Class 11 SAR Class 12 SAR Class 12A SAR Class 12B SAR Class 13 SAR Class 14 SAR Class 14A SAR Class 14B SAR Class 14C 1st SAR Class 14C 2nd SAR Class 14C 3rd SAR Class 14C 4th SAR Class 15 SAR Class 15A SAR Class 15B SAR Class 15C SAR Class 15CA SAR Class 15E SAR Class 15F SAR Class 16 SAR Class 16A SAR Class 16B SAR Class 16C SAR Class 16D SAR Class 16DA 1928 SAR Class 16DA 1930 SAR Class 16E SAR Class 17 SAR Class 18 SAR Class 19 SAR Class 19A SAR Class 19B SAR Class 19C SAR Class 19D SAR Class 20 SAR Class 21 SAR Class 23 SAR Class 24 SAR Class 25 SAR Class 25NC SAR Class 26 SAR Katanga SWA 2-8-0

3' 6" gauge Articulated engines	CGR Fairlie CGR Kitson-Meyer SAR Class FC SAR Class FD SAR Class GA SAR Class GB SAR Class GC SAR Class GCA SAR Class GD SAR Class GDA SAR Class GE SAR Class GEA SAR Class GF SAR Class GG SAR Class GH SAR Class GK SAR Class GL SAR Class GM SAR Class GMA SAR Class GO SAR Class HF SAR Class KM SAR Class MA SAR Class MB SAR Class MC SAR Class MC1 SAR Class MD SAR Class ME SAR Class MF SAR Class MG SAR Class MH SAR Class MJ SAR Class MJ1 SAR Class U

2' 6" gauge	Cape Copper John King & Miner Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay 2-4-2T Hope

2' & 600mm gauges	ACR Class NG-G16A CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A 2-6-4T CGR Type C 0-4-0T NGR Class N 4-6-2T SAR Dutton SAR NG 0-4-0T SAR Class NG1 SAR Class NG2 SAR Class NG3 SAR Class NG4 SAR Class NG5 SAR Class NG6 SAR Class NG7 SAR Class NG8 SAR Class NG9 SAR Class NG10 SAR Class NG-G11 SAR Class NG-G12 SAR Class NG-G13 SAR Class NG-G14 SAR Class NG15 SAR Class NG-G16 SWA Class Ha SWA Class Hb SWA Class Hc SWA Class Hd SWA Jung SWA Zwillinge

Electric

Amcoal Class E38

Gas-electric

SAR Gas-electric

Diesel

3' 6" gauge Diesel-electric	PRASA Class Afro 4000 SAR Class DS SAR Class DS1 SAR Class 31-000 SAR Class 32-000 SAR Class 32-200 SAR Class 33-000 SAR Class 33-200 SAR Class 33-400 SAR Class 34-000 SAR Class 34-200 SAR Class 34-400 SAR Class 34-500 SAR Class 34-600 SAR Class 34-800 SAR Class 34-900 SAR Class 35-000 SAR Class 35-200 SAR Class 35-400 SAR Class 35-600 TFR Class 35-800 SAR Class 36-000 SAR Class 36-200 SAR Class 37-000 Spoornet Class 39-000 TFR Class 39-200 TFR Class 43-000 TFR Class 44-000

2' gauge Diesel-electric	SAR Class 91-000

3' 6" gauge Diesel-hydraulic	SAR Class 61-000

3' 6" gauge Electro-diesel	Spoornet Class 38-000

South African steam locomotive tenders

Cape gauge	Type CL Type CZ Type ET Type ET1 Type EW Type EW1 Type EW2 Type FT Type GT Type HT Type JT Type JT1 Type JV Type KT Type LP Type MP Type MP1 Type MR Type MS Type MT Type MT1 Type MT2 Type MX Type MY Type MY1 Type SH Type SK Type TJ Type TL Type TM Type WE Type WG Type X-17 Type X-20 Type XC Type XC1 Type XD Type XE Type XE1 Type XF Type XF1 Type XF2 Type XJ Type XM Type XM1 Type XM2 Type XM3 Type XM4 Type XP1 Type XS Type YB Type YC Type YE Type YE1 Type ZA Type ZB Type ZC Type ZE

List of South African locomotive classes South African locomotive history

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