South African Class 7A 4-8-0

South African Class 7A 4-8-0
& South African Class 7AS 4-8-0
ex CGR 7th Class 4-8-0
Sudan Railways Dongola Class

Ex CGR (Eastern System) 7th Class no. 726
SAR Class 7A no. 1009
Type and origin
Power type Steam
Designer Cape Government Railways
Builder Sharp, Stewart and Company
Dübs and Company
Neilson and Company
Serial number Sharp, Stewart 4145-4152, 4363
Dübs 3355-3362, 3641-3652, 3976
Neilson 4920-4931, 5160-5163, 5232-5234, 5280-5281, 5345-5347 [1]
Model CGR 7th Class
Build date 1896-1898, 1901 [2]
Total produced 46
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 42.75 in (1,090 mm)
Wheelbase Total: 46 ft 2 in (14.072 m)
Engine:
5 ft 3 in (1.600 m) bogie
12 ft (3.658 m) coupled
21 ft 3.5 in (6.490 m) total
Tender:
4 ft 7 in (1.397 m) bogie
16 ft 1 in (4.902 m) total
Length 53 ft 5.75 in (16.300 m)
Height 12 ft 10 in (3.912 m)
Frame Plate frame
Axle load 9 long tons (9.1 t) on 1st & 2nd drivers as built
9.7 long tons (9.9 t) on 2nd driver superheated
Weight on drivers 35.8 long tons (36.4 t) as built
38 long tons (39 t) superheated
Locomotive weight 46.5 long tons (47.2 t) as built
49.1 long tons (49.9 t) superheated
Tender weight 32.35 long tons (32.869 t) w/o
Locomotive and tender
combined weight		 92,764 lb (42.077 t) empty
74.55 long tons (75.746 t) w/o
Tender type ZE - ZA, ZB, ZC, ZE permitted
* 2 axle bogies
* 34 in (864 mm) wheels
* Length 23 ft 8.5 in (7.226 m)
Fuel type Coal
Fuel capacity 8 long tons (8.1 t)
Water capacity 2,850 imp gal (13,000 l)
Boiler As built:
4 ft 4 in (1.321 m) inside diameter
10 ft 9 in (3.277 m) inside length
6 ft 8 in (2.032 m) pitch
Superheated:
4 ft 6 in (1.372 m) inside diameter
10 ft 9 in (3.277 m) inside length
8 ft 10 in (2.692 m) pitch
Boiler pressure 160 psi (1,100 kPa) as built
170 psi (1,170 kPa) adjusted
180 psi (1,240 kPa) superheated
Firegrate area 18 sq ft (1.672 m2)
Heating surface:
– Tubes		 As built:
185 tubes 1.875 in (47.6 mm) diameter
976 sq ft (90.673 m2)
Superheated:
100 tubes 1.875 in (47.6 mm) diameter
18 tubes 5.5 in (140 mm) diameter
806 sq ft (74.880 m2)
– Firebox 102 sq ft (9.476 m2) as built
113 sq ft (10.498 m2) superheated
– Total 1,078 sq ft (100.149 m2) as built
919 sq ft (85.378 m2) superheated
Superheater type Not equipped as built
Superheater area 206 sq ft (19.138 m2)
Cylinders Two
Cylinder size 17 in (432 mm) bore
23 in (584 mm) stroke
Valve gear Stephenson
Performance figures
Tractive effort At 75% boiler pressure, as built:
18,660 lbf (83.0 kN) at 160 psi (1,100 kPa)
19,810 lbf (88.1 kN) at 170 psi (1,170 kPa)
Superheated:
22,240 lbf (98.9 kN) [3]
Factor of
adhesion		 4.3 [4]
Career
Operator(s) Cape Government Railways
Bechuanaland Railway
Imperial Military Railways
Imvani-Indwe Railway
Sudan Military Railway
South African Railways
Zambesi Saw Mills
Class CGR 7th Class, SAR Class 7A
Number in class 46 CGR, 44 SAR
Number(s) CGR 347-350, 385-398, 718-744, 758
BR 4-7
IMR C522, C523 & C525-C527
Imvani-Indwe: Named
SAR 988-1031 [2][5][6]
Sudan 26-33 [1]
Delivered 1896-1901
First run 1896
Withdrawn 1972 [7]

The South African Class 7A 4-8-0 of 1896 is a South African steam locomotive from the pre-Union era in the Cape Colony.

Between 1896 and 1901 the Cape Government Railways placed a second batch of altogether forty-six 7th Class steam locomotives with a 4-8-0 Mastodon wheel arrangement in service on its Midland and Eastern Systems. In 1912, when all but two of them were assimilated into the South African Railways, they were renumbered and reclassified to Class 7A.[2][5][7]

In 1897 and 1898 eight Cape 7th Class locomotives were also built for the Soudan Military Railway during Kitchener’s military campaign in Sudan.[1][4]

Manufacturers

Following on the thirty-eight 7th Class locomotives that were placed in service by the Cape Government Railways (CGR) between 1892 and 1893, a second batch of slightly improved Cape 7th Class locomotives were acquired between 1896 and 1901. Outwardly all these locomotives appeared almost identical to the first batch of 7th Class locomotives, but they had increased heating capacity as well as some other modifications. The most noticeable difference lay in their Type ZE tenders that ran on bogies, compared to the three axle Type ZB tenders of the earlier locomotives.[2]

1896

In 1896 orders were placed for twenty-eight locomotives, distributed between three manufacturers.[2][4]

1897

In 1897 a further four 7th Class locomotives were ordered by the CGR from Neilson, along with three 6th Class locomotives, for use on the new Vryburg to Bulawayo line of the fledgling Bechuanaland Railway Company (BR). The line was still under construction and was operated by the CGR on behalf of the BR at the time. The 7th Class locomotives, numbered in the range from BR4 to BR7, were eventually returned to the CGR and renumbered in the range from 347 to 350 for the Cape Midland System.[2][4]

In 1897 and 1898 Neilson also built eight Cape 7th Class locomotives for the Soudan Military Railway, where they were known as the Dongola Class.[1][4]

1898

In 1898 another ten 7th Class locomotives were taken into service by the CGR, as well as three by the Imvani-Indwe Railway that operated a branch line from Sterkstroom to the Indwe Collieries in the Eastern Cape.[2]

1901

One more 7th Class locomotive was delivered by Dübs in 1901 and became the Cape Eastern System’s number 758.[4]

Class 7 sub-classes

The Union of South Africa was established on 31 May 1910, in terms of the South Africa Act. One of the clauses in the Act required that the three Colonial Government railways, the CGR, the Natal Government Railways 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.[5][8]

When all but two of these forty-six locomotives were assimilated into the SAR in 1912, they were renumbered in the range from 988 to 1031 and reclassified to Class 7A. The two exceptions had been sold to Pauling and Company in 1909.[2][5][6]

The rest of the CGR’s 7th Class locomotives, together with 7th Class locomotives from the Central South African Railways (CSAR), the Pretoria-Pietersburg Railway (PPR), the Rhodesian Railways (RR), the Natal Government Railways (NGR) and, in 1925, the New Cape Central Railways (NCCR), were grouped into six different sub-classes by the SAR, becoming SAR Classes 7 and 7B to 7F.[3]

Modifications

During the 1930s and later many of the Class 7 series locomotives were equipped with superheated boilers and piston valves. On the Class 7B and Class 7C this conversion was sometimes indicated with an "S" suffix to the class number on the locomotive’s number plates, but on the rest of the Class 7 family this distinction was rarely applied. The superheated versions could be visually identified by the position of the chimney on the smokebox, with the chimney displaced forward to provide space behind it in the smokebox for the superheater header.[3][7]

In the early 1960s Class 7A 1021 was equipped with a superheater and reclassified to the sole Class 7AS. The number plate was altered by weld-writing a crude "S" after the "7A". This locomotive spent its last working days on the SAR doing steam heating tests on mainline passenger coaches at the Braamfontein North passenger yard in Johannesburg, before being sold to the Zambesi Saw Mills (ZSM) in 1971. The ZSM engineer's records, however, show it as not superheated and having saturated boiler number 7865.

Renumberings

During their long service lives some of the Class 7A locomotives underwent more than one renumbering. Five saw service with the Imperial Military Railways (IMR) and were temporarily renumbered accordingly, three were unnumbered but named while in Imvani-Indwe colliery service and all but two were eventually renumbered into the SAR’s roster in 1912. The table below lists these renumberings as well as their builders and works numbers.[2][5][6]

When the four BR locomotives, BR 4 to 7, were eventually returned to CGR service and renumbered in the range from 347 to 350 for the Cape Midland System, it resulted in number duplication that confused historians in later years. These four running numbers had been used previously on four of the 1892 and 1893 batch of 7th Class locomotives, also built by Neilson, that had since been renumbered in the range from 712 to 715 when they were transferred from the Midland to the Eastern System.[2][4][5]

Service

Cape Government Railways

The 7th Class series became the main goods locomotive class for the last twenty years of the existence of the CGR. Of this second batch of the Class, not all began their service lives on the CGR and not all remained with the CGR until the SAR came into existence. In summary:

South African Railways

In SAR service, the Class 7 series worked on every system in the country. In 1915, during the South West African Campaign in World War I, twenty-nine Class 7 series locomotives were sent to South West Africa (SWA) to assist the expeditionary forces. Eleven of these were Class 7A locomotives, numbers 1000 to 1002, 1005, 1006, 1017, 1019 and 1021 to 1024.[4][7]

They proved so successful in that territory that more were gradually transferred there in later years. By the time the Class 24 arrived in SWA in 1949, there were still fifty-three Class 7 series locomotives in use there. Most remained there and were only transferred back to South Africa when the Class 32-000 diesel-electric locomotives replaced them in 1961. In South Africa they remained in branch line service, particularly at Tarkastad and Ladysmith and also on the line from Touws River to Ladismith, until they were finally withdrawn in 1972.[7]

Industrial

Four Class 7A locomotives, numbers 992 and 1006 in 1966 and 993 and 1021 in 1971, as well as two Class 7 and two Class 7B, were sold to the Zambesi Saw Mills (ZSM) in Zambia. The company worked the teak forests that stretched 100 miles (160 kilometres) to the north-west of Livingstone and it built one of the longest logging railways in the world to serve its sawmill at Mulobezi. These eight locomotives joined eight ex RR 7th Class locomotives that had been acquired by the ZSM between 1925 and 1956.[4]

Railway operations ceased at Mulobezi around 1972, whilst operation of the line to Livingstone was taken over by the Zambia Railways in 1973. While most of the Class 7 series locomotives remained at Mulobezi out of use, Class 7A 1021 was installed at the Livingstone factory to supply steam for curing wood.[9]

Sudan’s Dongola Class

Sudan Dongola Class (4-8-0), circa 1898

Known as the Dongola Class, Cape 7th Class locomotives were also built for the Soudan Military Railway during Kitchener’s campaign in Sudan. When he arrived in the territory in 1895, he built a railway line, strictly for military purposes, running parallel to the Nile River for nearly 200 miles (322 kilometres) from Wadi Halfa to the Third Cataract at Kerma, and then another line from Wadi Halfa across 571 miles (919 kilometres) through the Nubian Desert to Atbarah and on to Khartoum to the south. For motive power, three Cape 7th Class locomotives, built to the Class 7A design, were ordered from Neilson and delivered in 1897. These were followed by five more in two batches in 1898. They were initially not numbered, but named after places in Sudan.[1][4]

Their works numbers, order numbers, names and eventual Sudan Railway (SR) numbers are set out in the table. Number 29, which was originally named "Berber" according to Neilson’s records, was later renamed "Fashoda/Suakin".[1][4]

These locomotives were equipped with gates across the open ends of their cabs and pipes under the running board on the right side that terminated in hose connections below the front buffer beam, so that water tenders could be coupled to the front and they could be run cab forward. The reason was that they were used on a single line being constructed into the desert from Wadi Halfa, initially with no water supply at the far end.[4]

For some reason these locomotives were not popular in the Sudan and they were all withdrawn from service by 1914.[4]

Service illustrated

The main picture shows ex Cape Eastern System 7th Class 726, SAR Class 7A 1009, plinthed in Oudtshoorn in the Cape Province, while the following show the locomotive in service and preserved.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Neilson, Reid works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 41–44, 83. ISBN 978-0-7153-5382-0.
  3. ↑ 3.0 3.1 3.2 South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 Pattison, R.G. (1997). The Cape Seventh Class Locomotives (1st ed.). Kenilworth, Cape Town: The Railway History Group. pp. 7–10, 22–24, 38–39, 48–50. ISBN 0958400946.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 8, 12, 15, 38-39 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  6. ↑ 6.0 6.1 6.2 Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. p. 139. ISBN 978-0-7153-5427-8.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 46–48. ISBN 0869772112.
  8. ↑ The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.
  9. ↑ Pattison, R.G. (2005). Thundering Smoke, (1st ed.). Sable Publishing House. p42-48. ISBN 0-9549488-1-5