South African Class 6L 4-6-0

The South African Railways Class 6L 4-6-0 of 1904 was a steam locomotive from the pre-Union era in the Cape of Good Hope.

In 1904, the Cape Government Railways placed its last two 6th Class 4-6-0 bar-framed steam locomotives in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and reclassified to Class 6L.^[1][2][3]

Manufacturer

The Cape Government Railways (CGR) placed its last order for two 6th Class locomotives with Neilson, Reid and Company in 1903. In that same year, Scottish locomotive builders Sharp, Stewart and Company and Dübs and Company merged with Neilson, Reid to form the North British Locomotive Company (NBL). The two locomotives, Neilson, Reid works numbers 6324 and 6323, built at the Hyde Park works of the former Neilson, Reid, were therefore delivered with NBL works numbers 15889 and 15888.^[4]

Characteristics

The two locomotives in this order were experimental and were the first South African locomotives to have piston valves with internal admission and superheaters. Like other second generation 6th Class locomotives with bar frames, they had high running boards with no need for driving wheel fairings. The two locomotives were delivered in 1904, numbered 909 and 910 for the Western System of the CGR.^[1][3][5][6]

Cylinders

H.M. Beatty

The pistons, with a bore of 18.5 inches (470 millimetres), were the largest yet used on the 6th Class. The piston valves, arranged above the cylinders, were cast iron, 6 inches (152 millimetres) in diameter and actuated by Stephenson Link motion through rocking shafts. The balance weight was replaced by a compression spring, encased in a cast-steel cylinder.^[1][3][5][6]

A pressure relief valve was fitted to the cylinder covers and snifting valves were fitted to the steam chests. Lubrication of the cylinders and piston valves was by means of a Ritter six-piston oil press, which was arranged in the cab at the right hand side of the engine and actuated from the trailing crank pin.^[6]

Firebox

The boiler barrel was telescopic in form, with the larger diameter adjacent to the firebox. The front portion of the firebox was supported from the shell by means of partial girder stays, fitted with expansion links. The remaining portion was supported by through stays, each partially encased in an iron tube, filled with cement. The stays in the sides, the tubeplates and backplate were copper, while the 158 tubes were iron.^[6]

Schmidt superheater

These locomotives were the first engines to be built in Britain with the Schmidt superheater. While, in later superheater designs, the superheater elements were passed down the boiler flues, the Schmidt superheater was of the smokebox type and consisted of 61 solid drawn-steel tubes.^[1][6]

The superheater tubes were encased in a box which was built up of thin steel plates, adapted to the shape of the outer series of tubes, and ended at the steam collector box in two narrow vertical dampers. The whole superheater occupied two-thirds of the total length of the smokebox. To ensure that the superheater tubes received ample heat, a large flue of 10 ³⁄₄ inches (273 millimetres) diameter was installed in the lower part of the boiler between the firebox and the front tube plate, where it connected to the casing of the superheater.^[1][6]

The 61 tubes were bent into concentric rings and arranged in vertical planes, about 1 inch (25 millimetres) apart, each plane containing alternately two rings and one ring, with the one ring of a diameter intermediate between that of the other two rings. The first nine rings nearest the tubeplate, however, were arched in decreasing radii from the front of the flue to form a chamber between the inner and two outer rings, into which the gases from the large flue first passed.^[6]

The inner series of tubes were bent up at the ends and expanded into two cast-steel collector boxes, attached to the smokebox on each side of the chimney. The right hand side box was divided into two chambers by a central partition, with half the superheater tubes expanding into each of the chambers. The partition on the tube plate side of this box was connected to the regulator pipe, while the front partition was connected through the steam pipes to the cylinders. The left hand side steam collector box had no partition.^[6]

The action of the superheater was simple. Upon opening of the regulator, saturated steam was admitted to the rear chamber of the right hand side steam collector box, from where it passed through the tubes to the left hand side box in a slightly superheated condition. From there it passed back to the front chamber of the right hand side box through the other half of the tubes, and then, in a superheated condition, to the cylinders.^[6]

The rate of flow of the gases was controlled by the driver by means of dampers, placed at the top of the superheater box. These dampers were connected to the lever to actuate the blower, in such a manner that they were automatically closed when the blower was in operation.^[6]

In the smokebox, it was necessary to provide a clearing chute beneath the smokebox, where the flue joined the casing, to prevent it from becoming clogged with cinders. Just forward of the blast pipe, another chute was installed to clear cinders from the smokebox.^[1][6]

Class 6 sub-classes

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, 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]

When these two locomotives were assimilated into the SAR in 1912, they were renumbered 659 and 660 and reclassified to Class 6L.^[2][5][8]

The rest of the CGR's 6th Class locomotives, together with the Central South African Railways (CSAR) Classes 6-L1 to 6-L3 locomotives which had been inherited from the Oranje-Vrijstaat Gouwerment-Spoorwegen (OVGS) via the Imperial Military Railways (IMR), were grouped into thirteen more sub-classes by the SAR. The 4-6-0 locomotives became SAR Classes 6, 6A to 6H, 6J and 6K, the 2-6-2 locomotives became Class 6Y and the 2-6-4 locomotives became Class 6Z.^[2][5][8]

Modification

The superheater arrangement was extremely complicated and did not prove to be a success. The two engines were comparatively tested against two similar saturated steam locomotives, but did not achieve any appreciable economy. The piston valves were found to be too small in diameter and the additional complications in boiler and smokebox details led to the decision, in 1915, to reboiler the two locomotives with boilers similar to those used by the standard Class 6 locomotive, thus converting them to saturated steam locomotives. The piston-valve cylinders were also removed and replaced with smaller 17 ¹⁄₂ inches (444 millimetres) bore slide-valve cylinders. In this form, the locomotives were practically identical to the bar-framed Class 6J locomotives, which had been built by Neilson, Reid and Company in 1902, except that they still had cylinders with a 0 ¹⁄₂ inch (13 millimetres) larger bore.^[1][6]

Service

The Class 6 family of locomotives were introduced primarily as passenger locomotives, but when the class became displaced by larger and more powerful locomotive classes, it literally became a Jack-of-all-trades which proved itself as one of the most useful and successful locomotive classes ever to be designed at the Salt River shops. It went on to see service in all parts of the country, except Natal, and was used on all types of traffic.^[1]

In SAR service, the two Class 6L locomotives worked on the Cape mainline, until they were withdrawn and scrapped in 1934.^[3][8]

References

Wikimedia Commons has media related to South African Class 6L (4-6-0).

Locomotives of the Cape of Good Hope
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 Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid
3' 6" gauge	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 2-6-0 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 2-6-0ST CGR 1st Class 4-4-0 CGR 1st Class 4-4-0T CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T 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 1890 CGR 5th Class 1891 CGR 6th Class 1893 CGR 6th Class 1896 CGR 6th Class 1897 CGR 6th Class 1898 CGR 6th Class 1900 CGR 6th Class 1901 Baldwin CGR 6th Class 1901 Schenectady CGR 6th Class 1901 Neilson's CGR 6th Class 1902 CGR 6th Class 1904 CGR 6th Class 2-6-2 CGR 6th Class 2-6-4 CGR 7th Class 1892 CGR 7th Class 1896 CGR 7th Class 1902 CGR 8th Class 1901 CGR 8th Class 1902 CGR 8th Class 2-8-0 1903 CGR 8th Class 4-8-0 1903 CGR 8th Class 4-8-0 1903 Exp CGR 8th Class 2-8-0 1904 CGR 8th Class 4-8-0 1904 CGR 9th Class 1903 CGR 9th Class 1906 CGR 10th Class CGR Fairlie CGR Karoo 1903 CGR Karoo 1904 CGR Karoo Compound CGR Kitson-Meyer CGR Mountain 4-8-2 CGR Railmotor CGR Tandem Compound 1902 CGR Tandem Compound 1903 Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NCCR 7th Class 1899 NCCR 7th Class 1913 Port Elizabeth 0-4-0ST
2' 6" gauge	Cape Copper 0-6-0T Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay Hope
2' gauge	CGR Baldwin 2-6-0 CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A CGR Type B CGR Type C
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 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