South African Class Exp 6 4-8-0

South African Class Exp 6 4-8-0
ex CGR 10th Class 4-8-0

CGR 10th Class no. 880, circa 1906,
later SAR Class Experimental 6 no. 1244
Type and origin
Power type Steam
Designer Cape Government Railways
Builder Kitson and Company
Serial number 4375 [1]
Model CGR 10th Class [2][3]
Build date 1906
Total produced 1
Specifications
Configuration 4-8-0 "Mastodon"
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading wheel
diameter		 28.5 in (724 mm)
Driver diameter 48 in (1,220 mm)
Wheelbase Total: 49 ft 2.5 in (14.999 m)
Engine:
6 ft (1.829 m) bogie
13 ft 6 in (4.115 m) coupled
23 ft 4 in (7.112 m) total
Tender:
4 ft 7 in (1.397 m) bogie
16 ft 1 in (4.902 m) total
Length 56 ft 6.625 in (17.237 m)
Height 12 ft 10 in (3.912 m)
Axle load 13.05 long tons (13.3 t) on 2nd driver
Weight on drivers 49.5 long tons (50.3 t)
Locomotive weight 63.2 long tons (64.2 t)
Tender weight 39.7 long tons (40.3 t)
Locomotive and tender
combined weight		 102.55 long tons (104.2 t)
Tender type 2 axle bogies
33.5 in (851 mm) wheels
Fuel type Coal
Fuel capacity 7.5 long tons (7.6 t)
Water capacity 3,000 imp gal (14,000 l)
Boiler 5 ft (1.524 m) inside diameter
11 ft 4 in (3.454 m) inside length
7 ft 5 in (2.261 m) pitch
Boiler pressure 180 psi (1,240 kPa)
Firegrate area 31.2 sq ft (2.899 m2)
Heating surface:
– Tubes		 215 tubes 2 in (50.8 mm) diameter
1,274.6 sq ft (118.414 m2)
– Firebox 123.7 sq ft (11.492 m2)
– Total 1,398.3 sq ft (129.906 m2)
Cylinders Two
Cylinder size 20 in (508 mm) bore
24 in (610 mm) stroke
Valve gear Stephenson
Performance figures
Tractive effort 27,010 lbf (120 kN) at 75% pressure
Career
Operator(s) Cape Government Railways
South African Railways [1]
Class CGR 10th Class
SAR Class Exp 6 [2][3]
Number in class 1
Number(s) CGR 880, SAR 1244 [2][3]
Delivered 1906
First run 1906
Withdrawn 1938 [4]

The South African Class Experimental 6 4-8-0 of 1906 is a South African steam locomotive from the pre-Union era in the Cape Colony.

In 1906 the Cape Government Railways placed a single experimental 10th Class steam locomotive with a 4-8-0 Mastodon type 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 Experimental 6.[1][2][4]

Manufacturer

The Cape 10th Class steam locomotive was designed by H.M. Beatty, the Locomotive Superintendent of the Cape Government Railways (CGR) from 1896 to 1910. The designs were prepared at the Salt River shops of the CGR in Cape Town. It was in most respects a larger and more powerful version of his Cape 8th Class of 1904, later the Class 8F, and represented a further effort on Beatty’s part to improve the steaming efficiency of the 8th Class. The locomotive was delivered by Kitson and Company in 1906 and was numbered 880.[1][2][4]

Characteristics

It had Stephenson valve gear and used saturated steam. With this locomotive, as with the Cape 9th Class Mikado delivered by the same manufacturer earlier in that same year, Beatty overcame his aversion to boiler centre lines that exceeded twice the Cape gauge track width of 3 feet 6 inches (1.067 metres) above the railhead. The boiler pitch of the Cape 10th Class was at 7 feet 5 inches (2.261 metres).[1]

In the designs of the Cape 9th Class and the Cape 9th Class Mikado types, later the Classes Experimental 4 and Experimental 5, Beatty achieved improved steaming efficiency by extending the locomotive frames with bridle castings to accommodate deep and wide fireboxes. With the 10th Class he attempted to obtain a wide firebox by spreading the grate over the rear driving wheels, hence the requirement to raise the boiler centre line. The result was a firebox that was virtually a copy of the one that was used on the Hendrie B locomotive, later the Class 1 on the SAR, that was placed in service on the Natal Government Railways (NGR) in 1904.[1][4]

Service

The locomotive was placed in service on the Cape Eastern System, working on the mainline out of East London. It proved to be very successful in service and was able to handle loads of 280 long tons (284.5 tonnes) up the steep 1 in 40 gradient of the mainline that started right at the end of the departure platform at East London station at the time. This compared favourably to the 240 long tons (243.9 tonnes) that the Cape 8th Class could manage.[1][4]

Despite its good performance, the design was never repeated since some trouble was experienced with the firebox. Instead, Beatty decided that more powerful locomotives could be designed using the wide and deep firebox that he used in his Karoo Class locomotives, later the Class 5A and Class 5B, and the Cape 10th Class therefore remained one of a kind.[1]

South African Railways

The Union of South Africa was established on 31 May 1910, in terms of the South Africa Act, enacted by the Parliament of the United Kingdom. One of the clauses in the Act required that the three Colonial Government railways, the CGR, the NGR and the Central South African Railways, also be united under one single administration to control and administer the railways, ports and harbours of the Union. While the South African Railways (SAR) 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][5]

In 1912 the Cape 10th Class was classified as Class Experimental 6 and renumbered to 1244 on the SAR. It was withdrawn from service in 1938.[2][4]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. p. 72. ISBN 978-0-7153-5382-0.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 9, 12, 15, 43 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  3. ↑ 3.0 3.1 3.2 Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. p. 140. ISBN 978-0-7153-5427-8.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 83. ISBN 0869772112.
  5. ↑ The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.