South African Class 6L 4-6-0

From Wikipedia, the free encyclopedia
Jump to: navigation, search
South African Class 6L 4-6-0
SAR Class 6L (4-6-0) ex CGR.jpg
Ex CGR Class 6, SAR Class 6L, as built with Schmidt superheater and piston valves
Type and origin
Power type Steam
Designer Cape Government Railways
Builder North British
Serial number 15889 & 15888
Model CGR Class 6
Build date 1904[1]
Total produced 2
Specifications
Configuration 4-6-0 “Ten-wheeler” (USA)
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading wheel
diameter
28.5 in (724 mm)
Driver diameter 54 in (1,370 mm)
Trailing wheel
diameter
33.5 in (851 mm) (Tender wheels)
Wheelbase Engine 21 ftin (6.452 m)
With tender 45 ft 5.5 in (13.856 m)
Length 52 ft 3.25 in (15.932 m)
Height 12 ft 10 in (3.912 m)
Frame Bar frame
Axle load 13.45 long tons (13.67 t) on 2nd driver as built
13.15 long tons (13.36 t) on 3rd driver saturated
Weight on drivers 38.5 long tons (39.1 t) as built
38.15 long tons (38.76 t) saturated
Locomotive weight 52.35 long tons (53.19 t) as built
49.9 long tons (50.7 t) saturated
Tender weight 36 long tons (37 t)
Locomotive and tender
combined weight
88.35 long tons (89.77 t) as built
85.9 long tons (87.3 t) saturated
Fuel type Coal
Fuel capacity 5.5 long tons (5.6 t)
Water capacity 3,200 imp gal (15,000 l)
Boiler ftin (1.397 m) int dia
11 ft 2.25 in (3.410 m) int length
Boiler pressure 180 psi (1,240 kPa)
Firegrate area 18.75 sq ft (1.742 m2)
Heating surface:
– Tubes
As built:
158 tubes 2 in (50.8 mm) ext dia
924.87 sq ft (85.923 m2)
Saturated:
176 tubes 2 in (50.8 mm) ext dia
1,030 sq ft (95.690 m2)
– Flues 1 large 10.75 in (273 mm) dia tube
33.75 sq ft (3.135 m2) as built
– Firebox 109.5 sq ft (10.173 m2) as built
109 sq ft (10.126 m2) saturated
– Total 1,068.12 sq ft (99.232 m2) as built
1,139 sq ft (105.817 m2) saturated
Superheater type Schmidt, as built
Cylinders Two
Cylinder size 18.5 in (470 mm) bore as built
17.5 in (444 mm) bore saturated
26 in (660 mm) stroke
Valve gear Stephenson
Performance figures
Tractive effort At 75% boiler pressure:
22,250 lbf (98.973 kN) as built
19,910 lbf (88.564 kN) saturated
Career
Railroad(s) Cape Government Railways
South African Railways
Class CGR Class 6, SAR Class 6L
Number in class 2
Number CGR 909-910, SAR 659-660[1][2]
Official name CGR Class 6, SAR Class 6L
Delivered 1904
First run 1904
Withdrawn 1934
Disposition Scrapped

In 1904 the Cape Government Railways (CGR) placed its last two Class 6 4-6-0 bar framed steam locomotives in service. In 1912, when they were assimilated into the South African Railways (SAR), later renamed Spoornet and then Transnet Freight Rail (TFR), they were renumbered and reclassified to Class 6L.[1][3]

Manufacture[edit]

The Class 6 was designed at the Salt River works of the Cape Government Railways (CGR) at the same time as the Class 7. While the Class 7 was conceived primarily as a goods locomotive, the Class 6 was intended to be its fast passenger service counterpart.[1]

The CGR placed its last order for Class 6 locomotives with the North British Locomotive Company (NBL) in 1904. The two locomotives in this order were experimental and were the first South African locomotives to have piston valves and superheaters. The pistons, with a bore of 18.5 inches (470 millimetres), were the largest yet used on the Class 6. Like other second generation Class 6 locomotives, they had high running boards without driving wheel fairings. They were numbered 909 and 910 for the Western System.[1][3][4]

Schmidt superheater[edit]

Whereas in later superheater designs the superheater elements were passed down the boiler flues, on these two engines the Schmidt superheater was of the smokebox type with the tubes arranged around the shell of the smokebox. To ensure that the superheater tubes received ample heat, a large flue of 10.75 inches (273 millimetres) diameter was installed between the firebox and the front tube plate, where it connected to the casing of the superheater. In the smokebox it was necessary to provide a clearing chute beneath the smokebox where the flue joined the casing in order to prevent it from becoming clogged with cinders. Just forward of the blast pipe, another chute was installed to clear cinders from the firebox.[1]

Modification[edit]

The arrangement was extremely complicated and did not prove a success, with the result that in 1915 the two locomotives were reboilered with boilers similar to those used by the standard Class 6, thus converting them to saturated steam locomotives. The piston-valve cylinders were also removed and replaced with smaller 17.5 inches (444 millimetres) bore slide-valve cylinders. In this form they were practically identical to the bar framed Class 6J locomotives that were built by Neilson, Reid and Company in 1902, except that they still had cylinders with a 0.5 inches (12.7 millimetres) larger bore.[1]

Class 6 sub-classes[edit]

When these locomotives were assimilated into the newly established South African Railways (SAR) in 1912, they were renumbered 659 and 660 and reclassified to Class 6L. The rest of the CGR’s Class 6 locomotives, together with Class 6 locomotives that were inherited from the Oranje-Vrijstaat Gouwermentspoorwegen (OVGS) via the Imperial Military Railways (IMR) and the Central South African Railways (CSAR), as well as the CSAR’s own Classes 6-L1 to 6-L3, were grouped into thirteen more sub-classes by the SAR, the 4-6-0 locomotives becoming SAR Classes 6, 6A to 6H, 6J and 6K, the 2-6-2 locomotives becoming Class 6Y and the 2-6-4 locomotives becoming Class 6Z.[4][2]

Service[edit]

In SAR service the two Class 6L locomotives worked on the Cape main line until they were withdrawn and scrapped in 1934.[2][3]

The Class 6 series of locomotives were introduced primarily as passenger engines, but when the class became displaced by larger and more powerful locomotive classes, it literally became a “Jack-of-all-trades” that 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 Cape Town they held a monopoly over the suburban services until electrification arrived in 1928, and on the Reef they also worked these services between Randfontein and Springs until the loads became too heavy for them. They were employed on branch lines all over the country, Natal excluded, and practically every big station and many smaller ones had its quota of these handy locomotives to work the local passenger, goods and shunting services.[1][3]

Like the Class 7, the Class 6 family gave good service for many years. By the time the last ones were retired in 1973, the Class 6 series had achieved a service life of eighty years, a performance that can be matched by few, if any, other locomotive classes world wide.[1]

See also[edit]

References[edit]

  1. ^ a b c d e f g h i j Steam Locomotives of the South African Railways, vol 1: 1859-1910, (D.F. Holland, 1971), p54, p56, ISBN 0 7153 5382 9
  2. ^ a b c Steam Locomotives of the South African Railways, vol 2: 1910-1955, (D.F. Holland, 1972), p138, ISBN 0 7153 5427 2
  3. ^ a b c d Locomotives of the South African Railways - A Concise Guide (Leith Paxton & David Bourne, 1985), p44, ISBN 0 86977 211 2
  4. ^ a b South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended