South African Class 7 4-8-0

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South African Class 7 4-8-0
ex CGR 7th Class 4-8-0
SAR Class 7 975 (4-8-0) ex CGR 344.JPG
Ex CGR (Midland System) 7th Class no. 344
SAR Class 7 no. 975, Bloemfontein, 6 April 2006
Specifications
Power type Steam
Designer Cape Government Railways
Builder Dübs and Company
Neilson and Company
Serial number Dübs 2882-2887
Neilson 4446-4477 [1]
Model CGR 7th Class
Build date 1892 [1][2]
Total produced 38
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:
41 ft 4.375 in (12.608 m) with ZB tender
46 ft 2 in (14.072 m) with ZE tender
Engine:
5 ft 3 in (1.600 m) bogie
12 ft (3.658 m) coupled
21 ft 3.5 in (6.490 m) total
ZB Tender:
10 ft (3.048 m)
ZE Tender:
4 ft 7 in (1.397 m) bogie
16 ft 1 in (4.902 m) total
Length 50 ft 1 in (15.265 m) with ZB tender
53 ft 6 in (16.307 m) with ZE tender
Height 12 ft 4.5 in (3.772 m) as built
12 ft 10 in (3.912 m) superheated
Frame Plate frame
Axle load 9 long tons (9.1 t) on 3rd driver as built
9.7 long tons (9.9 t) on 2nd driver superheated
Weight on drivers 35.05 long tons (35.6 t) as built
38 long tons (38.6 t) superheated
Locomotive weight 45.5 long tons (46.2 t) as built
49.1 long tons (49.9 t) superheated
Tender weight Type ZB:
31,560 lb (14.3 t) empty
29.05 long tons (29.5 t) w/o
Type ZE: Unknown
Locomotive and tender
combined weight
92,176 lb (41.8 t) empty
74.55 long tons (75.7 t) as built
78.15 long tons (79.4 t) superheated
Tender type ZB - ZA, ZB, ZC, ZE permitted
3 axle ZB tender:
* 37 in (940 mm) wheels
* Length 20 ft 3.375 in (6.182 m)
2 axle bogies ZE tender:
* 34 in (864 mm) wheels
* Length 23 ft 8.5 in (7.226 m)
Fuel type Coal
Fuel capacity ZB 5 long tons (5.1 t)
ZE 8 long tons (8.1 t)
Water capacity ZB 2,370 imp gal (10,800 l)
ZE 2,850 imp gal (13,000 l)
Boiler As built:
4 ft 2 in (1.270 m) inside diameter
10 ft 9 in (3.277 m) inside length
6 ft 6 in (1.981 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:
186 tubes 1.75 in (44.4 mm) diameter
911 sq ft (84.635 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 99 sq ft (9.197 m2) as built
113 sq ft (10.498 m2) superheated
– Total 1,010 sq ft (93.832 m2) as built
919 sq ft (85.378 m2) superheated
Superheater type Not equipped as built
Superheater area 206 sq ft (19.138 m2) superheated
Cylinders Two
Cylinder size 17 in (432 mm) bore
23 in (584 mm) stroke
Valve gear Stephenson
Tractive effort At 75% boiler pressure, as built:
18,660 lbf (83.0 kN) at 160 psi (1,100 kPa)
18,810 lbf (83.7 kN) at 170 psi (1,170 kPa)
Superheated:
22,240 lbf (98.9 kN) [3]
Factor of
adhesion
4.20
Career
Operator(s) Cape Government Railways
Imperial Military Railways
South African Railways
Zambesi Saw Mills
Class Class 7
Number in class 38
Number(s) CGR 315-352
17 were renumbered 701-717
IMR C520, C521 & C524
SAR 950-987 [2][4][5]
Delivered 1892-1893
First run 1892
Withdrawn 1972 [6]

The South African Class 7 4-8-0 of 1892 is a South African steam locomotive from the pre-Union era in the Cape Colony.

In 1892 the Cape Government Railways placed six 7th Class steam locomotives with a 4-8-0 Mastodon wheel arrangement in service and between 1892 and 1893 another thirty-two were acquired. They were initially placed in service on the Cape Midland System, but were later distributed between the Cape Midland and Cape Eastern Systems. In 1912, when they were assimilated into the South African Railways, they were renumbered but retained their Class 7 classification.[2][4][6][7]

Manufacturers[edit]

In 1890 Michael Stephens, then Chief Locomotive Superintendent of the Cape Western System of the Cape Government Railways (CGR), accompanied by General Manager C.B. Elliot, visited Durban to examine and report on the new Dübs A 4-8-2T (later NGR Class D) tank locomotives that had been placed in service by the Natal Government Railways (NGR) in 1888. In Elliot’s subsequent report he stated his conviction that locomotives with eight-coupled wheels should be adopted for the coastal sections of the Cape Midland and Cape Eastern Systems, where fog and the damp atmosphere were detrimental to tractive adhesion.[2][7]

CGR Number plate

Following this report, a complete design for such a locomotive was prepared at the Salt River works under the supervision of Locomotive Superintendent H.M. Beatty. The last six of an order for fifty-six Cape 5th Class 4-6-0 locomotives from Dübs and Company were cancelled and substituted with an order for six of these new 7th Class locomotives. They were delivered in 1892 and numbered in the range from 315 to 320 for the Cape Midland System. Two of them, numbers 318 and 320, were later renumbered to 701 and 702 and re-allocated to the Cape Eastern System.[2][7]

Works plate, CGR no. 345

These six locomotives were followed by an order for another thirty-two locomotives, delivered from Neilson and Company between 1892 and 1893. These were initially numbered in the range from 321 to 352 for the Midland System. Fifteen of these were later renumbered in the range from 703 to 717 and re-allocated to the Eastern System.[2][7]

While the 6th Class, which was designed and ordered at the same time as the 7th Class, was conceived as a fast passenger locomotive, the 7th Class was conceived as its heavy goods locomotive counterpart. The 7th Class turned out to be a most useful and well liked class. It continued the good looks of the Cape’s locomotives with a strong construction and sound design, and some remained in service for nearly eighty years.[2]

Class 7 sub-classes[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 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.[4][8]

SAR Class 7 970 (4-8-0) ex CGR 703 ID.JPG

When these thirty-eight locomotives were assimilated into the SAR in 1912, they were renumbered in the range from 950 to 987, but they retained their Class 7 classification.[4][5]

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

Modification[edit]

During the 1930s many of the Class 7 series locomotives were equipped with superheated boilers or piston valves or both. On the Class 7B and Class 7C this conversion was sometimes indicated with an "S" suffix to the class letter on the locomotive number plate, 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][6]

Service[edit]

Government railways[edit]

The 7th Class became the main goods locomotive for the last twenty years of the existence of the CGR. Three of them also saw service with the Imperial Military Railways (IMR) during the Second Freedom War from 1899 to 1902, having been allocated to the IMR for the duration of the war.[6]

In SAR service, the Class 7 did duty on every system in the country. In 1915, during the South West Africa 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 7 locomotives, numbers 950, 952, 954, 957, 962, 967 to 969, 973, 979 and 984. One of them was lost at sea in the process and was subsequently replaced with Class 7A number 1000. The lost locomotive was recorded as being number 984; however, number 984 was photographed in service at Walvisbaai circa 1955.[6][7]

They proved so successful in that territory that more were gradually transferred there in later years. By the time the Class 24 locomotives arrived in SWA in 1949, there were still fifty-three locomotives of the Class 7 family in use there.[6][7]

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 Touws River-Ladismith branch line, until they were finally withdrawn in 1972.[6]

Industrial service[edit]

In 1966 two Class 7 locomotives, numbers 955 and 956, as well as four Class 7A 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 in Zambia 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.[7]

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 locomotives remained at Mulobezi out of use, number 955 was preserved at the Livingstone Railway Museum.[9]

Renumberings[edit]

During their long service lives some of the Class 7 locomotives underwent multiple renumberings. All were initially numbered into the Cape Midland System roster. Some were later renumbered into the Cape Eastern System roster, three saw service with the IMR and were temporarily renumbered accordingly, and all were eventually renumbered into the SAR’s roster in 1912. The table lists these renumberings as well as their builders and works numbers.[2][4][5]

Service illustrated[edit]

The main picture shows ex Cape Midland System Class 7 no. 344, later SAR Class 7 no. 975, plinthed at the Women’s Memorial in Bloemfontein. Of the plinthed locomotives displayed below, CGR no. 345 (SAR no. 976) at Klerksdorp is actually Midland no. 332, later Eastern no. 707 and eventually SAR no. 980. It was restored incorrectly bearing the CGR number plate and builder’s works plate of CGR no. 345.[10]

See also[edit]

References[edit]

 
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  1. ^ a b Neilson, Reid works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  2. ^ a b c d e f g h Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 40–41, 61. ISBN 978-0-7153-5382-0. 
  3. ^ a b c South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  4. ^ a b c d e Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 8, 12, 15, 37 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  5. ^ a b c Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 138–139. ISBN 978-0-7153-5427-8. 
  6. ^ 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. 
  7. ^ a b c d e f g Pattison, R.G. (1997). The Cape Seventh Class Locomotives (1st ed.). Kenilworth, Cape Town: The Railway History Group. pp. 4–7, 22–23, 38–39. ISBN 0958400946. 
  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
  10. ^ Middleton, John N. (2002). Railways of Southern Africa Locomotive Guide - 2002 (as amended by Combined Amendment List 4, January 2009) (2nd, Dec 2002 ed.). Herts, England: Beyer-Garratt Publications. p. 18.