South African Class 7B 4-8-0

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South African Class 7B 4-8-0
ex IMR 7th Class 4-8-0
ex CSAR 7th Class 4-8-0
ex NGR Class L 4-8-0
ex Rhodesia Railways 7th Class 4-8-0
44 7B 4-8-0 No 1056 at Voorbaai 1997-SEP-04.jpg
SAR Class 7BS 1056 at Voorbaai, 4 September 1997
Type and origin
Power type Steam
Designer Cape Government Railways
Builder Neilson, Reid and Company
Serial number 5677, 5813-5837, 5904-5906 [1]
Model CGR 7th Class
Build date 1900 [1][2][3]
Total produced 29
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 7.75 in (16.351 m)
Height 12 ft 10 in (3.912 m)
Frame Plate frame
Axle load 9.05 long tons (9.2 t) on 3rd driver as built
9.7 long tons (9.9 t) on 2nd driver superheated
Weight on drivers 36 long tons (36.6 t) as built
38 long tons (38.6 t) superheated
Locomotive weight 46.7 long tons (47.4 t) as built
49.1 long tons (49.9 t) superheated
Tender weight 34.1 long tons (34.6 t)
Locomotive and tender
combined weight
92,764 lb (42.1 t) empty
80.8 long tons (82.1 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
6 ft 10 in (2.083 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)
At 75% boiler pressure, superheated:
20,990 lbf (93.4 kN) at 160 psi (1,100 kPa)
22,240 lbf (98.9 kN) at 170 psi (1,170 kPa) [4]
Factor of
adhesion
4.32 [5]
Career
Operator(s) Imperial Military Railways
Rhodesia Railways
Mashonaland Railways
Beira-Mashonaland-Rhodesia
Rhodesia Railways Northern
Pretoria-Pietersburg Railway
Central South African Railways
Natal Government Railways
South African Railways
Zambesi Saw Mills
Class IMR-RR-PPR-NGR 7th Class
CSAR, SAR Class 7B
Number in class 29 IMR, RR & PPR
28 SAR
Number(s) IMR 106-130
PPR 7-9 [2]
RR 19 & 63 [3]
CSAR 373-400
NGR 327-329
SAR 949, 1032-1034, 1036-1058 [2][6]
Delivered 1900
First run 1900
Withdrawn 1972 [7]

The South African Class 7B 4-8-0 of 1900 is a South African steam locomotive from the pre-Union era in the Transvaal.

In 1900 the Imperial Military Railways placed twenty-five Cape 7th Class 4-8-0 Mastodon type steam locomotives in service. In that same year, three Cape 7th Class locomotives that had been ordered by the Pretoria-Pietersburg Railway were also placed in service. All these locomotives were taken on to the Central South African Railways roster at the end of the Second Boer War in 1902. In 1906 three of these locomotives were sold to the Natal Government Railways.[2][3][7]

In 1912 twenty-six of these twenty-eight locomotives were assimilated into the South African Railways. They were followed in 1913 by the remaining two that had been leased to Paulings as construction locomotives. All but one of these locomotives were renumbered and reclassified to Class 7B. In 1915 one more Cape 7th Class locomotive was obtained from the Rhodesia Railways and erroneously also classified as Class 7B.[2][3][6][7]

Background[edit]

After the outbreak of the Anglo-Boer War in 1899, control of all railways in the Cape and Natal Colonies remained in the hands of their civil staff, but now working in co-operation with the invading British military. As possession was obtained of the lines of the Orange Free State and the Zuid-Afrikaansche Republiek, the Oranje-Vrijstaat Gouvernement-Spoorwegen (OVGS) and the Nederlandsche-Zuid-Afrikaansche Spoorweg-Maatschappij (NZASM) were combined into the Imperial Military Railways (IMR), in the hands of military and civilian staff appointed by the Director of Railways for the South African Field Forces, Lieutenant Colonel E.P.C. Girouard, KCMG, DSO, RE.[2]

Manufacturer[edit]

Because of the damage caused during hostilities and the demands of the armed forces, a shortage of locomotives developed. In 1900 the IMR placed an order with Neilson, Reid and Company for twenty-five Cape 7th Class locomotives, which were numbered in the range from 106 to 130 upon delivery.[2]

Also in 1900, three Cape 7th Class locomotives that had been ordered by the Pretoria-Pietersburg Railway (PPR) were placed in service by the IMR, also built by Neilson, Reid. Numbered PPR 7 to 9, these were the last locomotives to be ordered by the PPR before it ceased to exist upon its incorporation into the NZASM, which itself was subsequently incorporated into the IMR.[2]

One more locomotive in the group that was eventually to become the South African Railways (SAR) Class 7B, was part of a batch of Cape 7th Class locomotives that had been built for the Rhodesia Railways (RR) by Neilson, Reid in 1899 and placed in service in 1900.[2]

All these locomotives were built to the same design as the 1896 to 1898 batch of 7th Class engines of the Cape Government Railways (CGR) that were later to be designated SAR Class 7A, with their increased heating capacity and type ZE bogie-wheeled tenders.[2]

Transfers and renumberings[edit]

After the cessation of hostilities on 1 June 1902, the IMR was transferred to civil control on 1 July 1902 and renamed the Central South African Railways (CSAR). The IMR and PPR 7th Class locomotives were renumbered by the CSAR in the ranges from 373 to 397 and 398 to 400 respectively.[2]

Natal Government Railways[edit]

In 1906 three of these locomotives, CSAR numbers 384, 389 and 393, were sold to the Natal Government Railways (NGR) to work on the Harrismith-Bethlehem section in the Orange River Colony (ORC). They were designated the NGR Class L and renumbered in the range from 327 to 329.[2]

SAR classification[edit]

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 NGR and the CSAR, also be united under one single administration to control and administer the railways, ports and harbours of the Union. While the 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.[6][8]

When all of these locomotives, with three exceptions, were assimilated into the SAR in 1912, they were renumbered in the ranges from 1032 to 1034, 1036 to 1039 and 1041 to 1058 and reclassified to Class 7B.[2][3][6]

Leased locomotives[edit]

The first two exceptions, ex IMR numbers 106 and 113, later CSAR numbers 376 and 383 respectively, had been leased to Pauling and Company in 1911 for use on a construction contract and were only returned to the SAR in January 1913. They then received the numbers 1035 and 1040 respectively, which had been reserved for them even though the numbers were not listed in the 1912 renumbering tables.[2][3][6][9]

Classification errors[edit]

Two locomotives that returned to South Africa from Rhodesia circa 1915 were both incorrectly classified, possibly as a result of their records getting exchanged in an apparent administrative error.[2]

  • IMR no. 110, the third exception mentioned above, would have become CSAR no. 380 in 1902, but never did since it had already been transferred, as replacement for a war-damaged locomotive, to the Beira and Mashonaland and Rhodesia Railways (BMR) at Umtali in March 1901, where it was renumbered to MR no. 19. When it was eventually sold back to South Africa and was taken onto the SAR roster in 1915, it was incorrectly classified as a Class 7D instead of a Class 7B and was renumbered 1355.[2][5]
  • In 1915 the sole ex RR locomotive mentioned earlier was brought onto the SAR’s Class 7B roster as SAR no. 949. It had started its service life as RR no. 1 and was renumbered twice. In the 1901 Rhodesian renumbering it was renumbered to MR no. 8 on the BMR. In the 1906 Rhodesian renumbering it was renumbered again, this time to no. 63 on the Rhodesia Railways Northern Extensions (RRM, operating north and east of Bulawayo). This locomotive was part of the same batch of ex RR locomotives of which some became SAR Class 7D and it was therefore incorrectly classified as a Class 7B.[5][10]

The table shows all these renumberings except the multiple Rhodesian renumberings of SAR no. 949, as well as the builder’s works numbers.[1][2][3][6]

Class 7 sub-classes[edit]

Other 7th Class locomotives that came onto the SAR roster from the Colonial and other railways in the region, namely the CGR, the NGR, some from the RR and, in 1925, from the New Cape Central Railways (NCCR), were grouped into six different sub-classes by the SAR, becoming SAR Classes 7, 7A and 7C to 7F.[4][6]

Modifications[edit]

During their CSAR days, many of these locomotives were equipped with larger cabs and one, CSAR no. 381, later SAR no. 1058, was also reboilered with a larger round-top boiler. The reboilered locomotive was reportedly also equipped with Drummond tubes in its firebox, but these were found to be unsatisfactory and were soon removed. While the larger boiler enabled the locomotive to take the same load as a Class 8-L2, the cost of modifying the frame and problems with overloaded bearings led to a decision not to convert any of the others.[2][5][7]

Class 7BS 1056 (4-8-0) IDR.JPG

During the 1930s many of the Class 7 series locomotives were equipped with superheated boilers and piston valves. On the Classes 7B and 7C this conversion was sometimes indicated with an "S" suffix to the class number on the locomotive number plates, but on the rest of the Class 7 family this distinction was rarely applied. The superheated versions could be 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.[4][6][7]

Service[edit]

Government railways[edit]

In SAR service, the Class 7 series worked on every system in the country. 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. Five of these were Class 7B locomotives, numbers 1042 to 1044, 1051 and 1052.[5][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 branchline service, particularly at Tarkastad and Ladysmith and also on the Makadas line from Touws River to Ladismith, until they were finally withdrawn in 1972.[7]

Industry[edit]

In 1966 two Class 7B locomotives, numbers 1037 and 1040, as well as two Class 7 and four Class 7A locomotives were sold to the Zambesi Saw Mills (ZSM) in Zambia. The company worked the teak forests that stretched 100 miles (160 kilometres) to the northwest 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.[5]

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 7th Class series locomotives remained at Mulobezi out of use, Class 7A no. 1021 and Class 7B no. 1040 were installed at the Livingstone factory to supply steam for curing wood. Number 1040 was still in use in October 1995, when it was found in steam.[10]

Service illustrated[edit]

The main picture shows SAR Class 7B no. 1056 (ex IMR no. 123, ex CSAR no. 389, ex NGR no. 328) at Voorbaai, Mosselbaai, on 4 September 1997. Some of the modifications and applications of the Class 7B are illustrated below.

See also[edit]

References[edit]

  1. ^ a b c Neilson, Reid works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  2. ^ a b c d e f g h i j k l m n o p q r Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 105, 120, 122–124, 126, 133–134. ISBN 978-0-7153-5382-0. 
  3. ^ a b c d e f g Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 32, 139. ISBN 978-0-7153-5427-8. 
  4. ^ a b c South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  5. ^ a b c d e f Pattison, R.G. (1997). The Cape Seventh Class Locomotives (1st ed.). Kenilworth, Cape Town: The Railway History Group. pp. 12–15, 24–32, 38–39, 56. ISBN 0958400946. 
  6. ^ a b c d e f g h Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 8, 12, 15, 39 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  7. ^ a b c d e f g 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. ^ Information supplied by John N. Middleton
  10. ^ a b Pattison, R.G. (2005). Thundering Smoke, (1st ed.). Sable Publishing House. pp. 42-48. ISBN 0-9549488-1-5