South African Class Exp 2 2-8-0
Encyclopedia
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 Class 8 of 1901. In 1912, when the locomotive was assimilated into the South African Railways, it was renumbered and classified as Class Experimental 2.
of the previous year and was numbered 804, but it was not classified by the CGR and was simply referred to as the Tandem Compound.
in 1867. In a tandem compound locomotive each pair of high and low pressure cylinders drove a common crosshead, connecting rod and crank. The high pressure cylinders were bolted on to 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.
The high-pressure cylinders were 13 inches (330.2 mm) diameter and the low-pressure cylinders 23 inches (584.2 mm), with a common stroke of 26 inches (660.4 mm). 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.
Cape Government Railways
The Cape Government Railways was the government-owned railway operator in the Cape Colony from 1874 until the creation of the South African Railways in 1910.-Private railways:...
placed a single experimental 2-8-0
2-8-0
Under the Whyte notation for the classification of steam locomotives, 2-8-0 represents the wheel arrangement of two leading wheels on one axle , eight powered and coupled driving wheels on four axles, and no trailing wheels...
Consolidation type tandem compound steam locomotive in service, based on its Schenectady built Class 8 of 1901. In 1912, when the locomotive was assimilated into the South African Railways, it was renumbered and classified as Class Experimental 2.
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 Class 8South African Class 8X 2-8-0
Between 1901 and 1902 the Cape Government Railways placed sixteen Class 8 2-8-0 Consolidation type steam locomotives in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and reclassified to Class 8X...
of the previous year and was numbered 804, but it was not classified by the CGR and was simply referred to as the Tandem Compound.
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, steam is expanded just once in any one cylinder before being exhausted through the smokebox.Tandem compound
The tandem compound locomotive first appeared on the American Erie RailroadErie Railroad
The Erie Railroad was a railroad that operated in New York State, New Jersey, Pennsylvania, Ohio, Indiana, and Illinois, originally connecting New York City with Lake Erie...
in 1867. In a tandem compound locomotive each pair of high and low pressure cylinders drove a common crosshead, connecting rod and crank. The high pressure cylinders were bolted on to 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.
The high-pressure cylinders were 13 inches (330.2 mm) diameter and the low-pressure cylinders 23 inches (584.2 mm), with a common stroke of 26 inches (660.4 mm). 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.
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.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 locomotive.Service
The locomotive was placed in service on the lower section of the Cape main line, where it was used with limited success until it was converted to simple steaming. In 1912, when it was assimilated into the South African Railways (SAR), it was classified as Class Experimental 2 and renumbered to 908. It remained in SAR service only until 1916, when it was withdrawn.See also
- South African Class 8X 2-8-0South African Class 8X 2-8-0Between 1901 and 1902 the Cape Government Railways placed sixteen Class 8 2-8-0 Consolidation type steam locomotives in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and reclassified to Class 8X...
- South African Class Exp 1 4-6-2South African Class Exp 1 4-6-2In 1907 the Cape Government Railways placed a single experimental three cylinder compound steam locomotive with a 4-6-2 Pacific wheel arrangement in service, based on the second series of the Karoo Class locomotives...
- South African Class Exp 3 2-8-0South African Class Exp 3 2-8-0In 1903 the Cape Government Railways placed a single experimental 2-8-0 Consolidation type tandem compound steam locomotive in service, based on its Schenectady built Class 8 of 1901. It was similar to the tandem compound delivered a year earlier, but with a larger firegrate and an increased...
- South African Class Exp 4 2-8-2South African Class Exp 4 2-8-2In 1903 the Cape Government Railways placed two Class 9 steam locomotives with a 2-8-2 Mikado wheel arrangement in service. In 1912, when these locomotives were assimilated into the South African Railways, they were renumbered and classified as Class Experimental 4.-Manufacturer:The Cape Class 9...
- South African Class Exp 5 2-8-2South African Class Exp 5 2-8-2In 1906 the Cape Government Railways placed a single experimental steam locomotive with a 2-8-2 Mikado wheel arrangement in service. In 1912, when this locomotive was assimilated into the South African Railways, it was renumbered and classified as Class Experimental 5.-Manufacturer:The Cape Mikado...
- South African Class Exp 6 4-8-0South African Class Exp 6 4-8-0In 1906 the Cape Government Railways placed a single experimental Class 10 steam locomotive with a 4-8-0 Mastodon wheel arrangement in service on the Cape Eastern System. In 1912, when this locomotive was assimilated into the South African Railways, it was renumbered and classified as Class...
- The 2-8-0 "Consolidation"
- List of South African locomotive classes