South African Class FC 2-6-2+2-6-2

The South African Railways Class FC 2-6-2+2-6-2 of 1925 was an articulated steam locomotive.

In 1925, the South African Railways placed a single experimental Class FC Modified Fairlie articulated steam locomotive with a 2-6-2+2-6-2 Double Prairie type wheel arrangement in service.^[1][2][3]

Manufacturer

To obtain experience with another type of articulated locomotive similar to the Garratt design, Colonel F.R. Collins DSO, Chief Mechanical Engineer of the South African Railways (SAR), was authorised to experiment with a modified type of Fairlie locomotive. The sole experimental Class FC 2-6-2+2-6-2 Double Prairie type Modified Fairlie locomotive was designed and built for the SAR by the North British Locomotive Company in 1924. It was numbered 2310 upon delivery during February 1925, but it was later renumbered to 670.^[1][2][3][4]

The Fairlie locomotive

The Fairlie locomotive was invented and patented in 1864 by the Scottish engineer Robert Francis Fairlie.^[5][6]

Double Fairlie

Cape Government Railways Double Fairlie, c. 1888

The first Fairlie locomotives later became known as Double Fairlies. In general appearance, most of them were reminiscent of the German-built Zwillinge, which saw service on the narrow gauge lines in South West Africa and other German territories. However, while the Zwillinge were pairs of individual locomotives which were semi-permanently coupled back-to-back, the Double Fairlie was a single locomotive with either a double-ended boiler or two separate boilers, with smokeboxes at each end, a central firebox and a central cab, all mounted on one rigid frame. It ran on two swiveling engine units or powered bogies, similar to those of a Garratt locomotive, with the cylinders on each engine unit at the respective locomotive ends. Couplers, buffers and, where they were in use, cowcatchers were mounted on the engine units so that they could more accurately follow the curvature of the track.^[5][6]

Single Fairlie

A variation of the Fairlie concept was the Single Fairlie, also known as the Mason Fairlie. The Single Fairlie design was essentially half a Double Fairlie. It retained the ability to negotiate sharp curves and, while it abandoned the bidirectional nature of the Double Fairlie, it regained the ability of conventional locomotives to have a large water and coal bunker behind the cab and to use a trailing tender if necessary.^[5][6]

Swindon Marlborough & Andover Railway Single Fairlie, c. 1878

Early Single Fairlies were similar in appearance to tank locomotives. They differed by virtue of the fact that the whole engine and bunker or tender combination was mounted on a single rigid frame, as on the conven­tional tank engine, with the pivoting engine unit mounted under the boiler and the unpowered bogie under the bunker or tender.^[5][6]

Mason Bogie Single Fairlie, c. 1874

Later models were similar in appearance to conven­tional tender locomotives. It was developed by William Mason in the United States of America, where the type became known as the Mason Bogie. It had one boiler, a cab and bunker at one end, a single engine unit or powered bogie under the boiler and an unpowered bogie under the cab and bunker.^[5][6]

Modified Fairlie

The first Modified Fairlie was introduced in South Africa and was viewed as a competitor and alternative to the Garratt type. Colonel Collins displayed a distinct preference for articulated locomotives and the Modified Fairlie was acquired as an experimental locomotive in 1925, to compare its concept to that of the Garratt locomotive in terms of actual performance and maintenance requirements.^[1][2][3]

The Class FC Modified Fairlie was, in essence, an adaptation of the Kitson-Meyer concept. It was similar in appearance to a Garratt, but with the boiler, cab, coal and water bunkers all mounted on a single rigid frame, which extended almost over the full length of the locomotive. This superstructure was supported on two engine units by means of pivot centres, located approximately at the centre of the coupled wheelbase of each engine unit. In the Garratt design, by comparison, the coal and water bunkers are mounted directly on the engine units and pivot with them, while the boiler, firebox and cab are mounted on a rigid cradle frame which is suspended between the two engine units.^[1][2][3][7]

On the Modified Fairlie, as compared to the Double Fairlie, the distance between the engine units had been increased similarly to that of the Garratt type, thereby allowing space between them for a liberal firebox and ashpan. This resulted in a more efficient boiler and also distributed the weight of the engine over a greater length than was obtainable with an orthodox Double Fairlie design. It was claimed that the Modified Fairlie arrangement reduced the wear between wheel flanges and rails, and that the distribution of the loads on the axles, as fuel and water was expended, was less variable than could be obtained with the Garratt design.^[2]

Characteristics

The superheated Class FC had 7 inches (178 millimetres) diameter piston valves, actuated by Walschaerts valve gear, and a plate frame, ⁷⁄₈ inch (22 millimetres) thick. The aim with the experimental locomotive was to compare the performance and maintenance requirements of the Modified Fairlie to that of a Garratt, in particular to the Class GC 2-6-2+2-6-2 Double Prairie type Garratt, which was similar in both size and mechanical respects. Hence, also, the experimental Modified Fairlie's Class FC designation, skipping the FA and FB classifications which were never used by the SAR.^[2][3]

Service

The locomotive was placed in service on the Cape Midlands System. While it gave good service, it was not outstanding and proved to be not as successful as the Garratt. The 63 feet (19.2 metres) long frame resulted in severe overhang on sharp curves. The heavily laden overhangs beyond the pivots also led to metal fatigue due to its tendency to oscillate up-and-down. The pivot bearings, which carried a considerable additional load compared to those on the Garratt, as a result of the water and coal bunkers which were mounted on the long main frame instead of on the engine units, were also subject to quite rapid wear. These factors resulted in increased frequency of maintenance and, as a consequence, increased operating cost.^[1][3][7]

No more of the Class FC locomotive was ordered. The sole locomotive was scrapped in 1939, after a comparatively short service life of only fourteen years.^[1][2][3]

References

Wikimedia Commons has media related to South African Class FC (2-6-2+2-6-2).

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 SAR Class ES SAR Class ES1 SAR Class Exp-AC SAR Class 1E SAR Class 2E SAR Class 3E SAR Class 4E SAR Class 5E s1 SAR Class 5E s2 SAR Class 5E s3 SAR Class 5E1 s1 SAR Class 5E1 s2 SAR Class 5E1 s3 SAR Class 5E1 s4 SAR Class 5E1 s5 SAR Class 6E SAR Class 6E1 s1 SAR Class 6E1 s2 SAR Class 6E1 s3 SAR Class 6E1 s4 SAR Class 6E1 s5 SAR Class 6E1 s6 SAR Class 6E1 s7 SAR Class 6E1 s8 SAR Class 6E1 s9 SAR Class 6E1 s10 SAR Class 6E1 s11 SAR Class 7E SAR Class 7E1 SAR Class 7E2 s1 SAR Class 7E2 s2 SAR Class 7E3 s1 SAR Class 7E3 s2 Spoornet Class 7E4 SAR Class 8E SAR Class 9E s1 SAR Class 9E s2 SAR Class 10E SAR Class 10E1 s1 Spoornet Class 10E1 s2 SAR Class 10E2 SAR Class 11E SAR Class 12E Spoornet Class 14E Spoornet Class 14E1 TFR Class 15E Spoornet Class 16E Spoornet Class 17E Spoornet Class 18E s1 TFR Class 18E s2 TFR Class 19E TFR Class 20E TFR Class 21E TFR Class 22E
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
List of South African locomotive classes South African locomotive numbering and classification