South African Class GMA 4-8-2+2-8-4

South African Classes GMA & GMAM 4-8-2+2-8-4

Class GMAM no. 4079 "Lindie Lou" at Capital Park, 30 September 2006
Type and origin
Power type Steam
Designer South African Railways
Builder Henschel and Son
Beyer, Peacock and Company
North British Locomotive Company
Serial number Henschel 28680-28704, 29600-29629
BP 7550-7552, 7677-7681, 7750-7776, 7826-7855
NBL 27691-27702, 27769-27778, 27783-27792
Model Class GMA
Build date 1953-1958
Total produced 120
Specifications
Configuration 4-8-2+2-8-4 "Double Mountain" Garratt
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading dia 30 in (762 mm)
Driver diameter 54 in (1,372 mm)
Trailing dia 30 in (762 mm)
Minimum curve 275 ft (84 m)
Wheelbase Total: 86 ft 4 in (26,314 mm)
Engines:
6 ft 10 in (2,083 mm) bogie
14 ft 5 in (4,394 mm) coupled
30 ft 4 in (9,246 mm) total
Length 93 ft 10 in (28,600 mm)
Height 13 ft (3,962 mm)
Frame Cast frame, 45 ft (13,716 mm) between pivot centres
Axle load GMA 15.35 long tons (15.6 t) on 7th driver
GMAM 15.7 long tons (16.0 t) on 7th driver
Adhesive weight GMA 119.85 long tons (121.8 t)
GMAM 122.15 long tons (124.1 t)
Loco weight 347,800 lb (157.8 t) empty
GMA 187.05 long tons (190.1 t) w/o
GMAM 191.4 long tons (194.5 t) w/o
Fuel type Coal
Fuel capacity GMA 11.6 long tons (11.8 t)
GMAM 14 long tons (14.2 t)
Water cap GMA 1,650 imp gal (7,500 l) front
GMAM 2,100 imp gal (9,500 l) front
6,750 imp gal (30,700 l) in Type X-20 auxiliary tank wagon
Firebox:
 • Firegrate area		 63.2 sq ft (5.871 m2)
Boiler 6 ft 11.5 in (2,121 mm) inside diameter at 1st ring
7 ft 1.25 in (2,165 mm) inside diameter at firebox
13 ft 6.5 in (4,128 mm) inside length
8 ft 6 in (2,591 mm) pitch
Boiler pressure 200 psi (1,380 kPa)
Heating surface 3,211.2 sq ft (298.330 m2)
 • Tubes 282 tubes 2 in (51 mm) diameter
50 tubes 5.5 in (140 mm) diameter
2,974 sq ft (276.294 m2)
 • Flues 25.2 sq ft (2.341 m2)
 • Firebox 212 sq ft (19.695 m2)
Superheater:
 • Heating area		 747 sq ft (69.399 m2)
Cylinders Four
Cylinder size 20.5 in (521 mm) bore
26 in (660 mm) stroke
Valve gear Walschaerts
Performance figures
Tractive effort 60,700 lbf (270 kN) at 75% pressure
Career
Operators South African Railways
Class Class GMA, Class GMAM
Number in class 120
Numbers 4051-4170
Delivered 1954-1958
First run 1954
Withdrawn 1988

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The South African Railways Class GMA 4-8-2+2-8-4 of 1954 is an articulated steam locomotive.

Between 1954 and 1958 the South African Railways placed one hundred and twenty Class GMA branchline and Class GMAM mainline Garratt articulated steam locomotives with a 4-8-2+2-8-4 Double Mountain type wheel arrangement in service. This was the most numerous Garratt class in the world.[1][2][3][4][5]

Manufacturers

The light rail branchline Class GMA and mainline Class GMAM Garratt locomotives were a development of the large Class GM branchline locomotive that was introduced on the South African Railways (SAR) in 1938. Designed in 1952 under the supervision of L.C. Grubb, Chief Mechanical Engineer (CME) of the SAR from 1949 to 1954, an order for the first twenty-five of these locomotives was placed with Henschel and Son in Germany. They were built in 1953 and were delivered and placed in service in 1954, numbered in the range from 4051 to 4075.[6][7]

A second batch of thirty-five locomotives was delivered by Beyer, Peacock and Company (BP) in 1956. Of these, twenty-three were built by BP and numbered in the range from 4076 to 4098, while the other twelve, numbered in the range from 4099 to 4110, had been subcontracted by BP to the North British Locomotive Company (NBL). These twelve were therefore allocated works numbers by BP as well as by NBL.[6][8][9][10]

BP & NBL works plate off no. 4140

This was followed by a third and final batch of sixty locomotives in 1958. Of these, thirty were delivered by BP, of which only ten, numbered in the range from 4121 to 4130, had actually been built by BP. The other twenty, numbered in the ranges from 4111 to 4120 and 4131 to 4140, had once again been subcontracted by BP to NBL. These twenty were therefore also allocated works numbers by BP as well as by NBL. The order for the last thirty locomotives, numbered in the range from 4141 to 4170, had again been placed with Henschel in Germany.[1][6][7][8][9][10]

The builders, works numbers and year built of these locomotives are listed in the table.[6][7][8][9][10]

Characteristics

As was done with the predecessor Class GM, the new locomotive carried water only in its front tank, but with the capacity increased from the Class GM’s 1,600 imperial gallons (7,300 litres) to either 1,650 imperial gallons (7,500 litres) for the Class GMA or 2,100 imperial gallons (9,500 litres) for the Class GMAM. Likewise, the rear bunker carried only coal, but with the capacity increased from the Class GM’s 10 long tons (10 tonnes) to either 11.6 long tons (12 tonnes) for the Class GMA or 14 long tons (14 tonnes) for the Class GMAM.[1][4]

The designs of the light rail branchline Class GMA and the mainline Class GMAM were identical and their water and coal capacities were adjusted to suit by installing or removing plates in the coal and water spaces. As a result, it is virtually impossible to list the GMA and GMAM versions separately since they could easily be converted back and forth between the two versions, and often were. Up until about 1962, for example, the division was twenty Class GMA and one hundred Class GMAM, but by 1969 there were sixty-nine Class GMA and forty-nine Class GMAM, two having by then been scrapped after accident damage. By 1975, on the other hand, there were only twenty-five Class GMA against ninety-three Class GMAM.[1][3][4]

Type X-20 water tender

As with the Class GM, the water supply was also augmented by semi-permanently coupling a purpose-built Type X-20 auxiliary tank wagon with a capacity of 6,750 imperial gallons (30,700 litres) to the locomotive.[1][5]

Some of these locomotives, intended for working in areas where there were tunnels such as on the East London mainline, were initially equipped with steam operated smoke deflecting cowls over their chimneys. When the smoke cowls were later removed, these specific locomotives could still be identified by their almost non-existent chimneys, that had to be shorter in order to enable the cowls to fit within the loading gauge.[1][5]

The locomotive was designed to operate on 60 pounds per yard (30 kilograms per metre) rails despite the maximum axle loading of 15.7 long tons (16 tonnes) of the GMAM. This had been accomplished by restricting the weight on the pilot bogies to 22 tons and balancing the coupled wheels so that the hammer blow was equal for all wheels and did not exceed one ton on any wheel at 45 miles per hour (72 kilometres per hour).[1]

It was thoroughly modern in design with a one piece "Commonwealth" cast steel frame with Franklin spring-loaded wedge horns, manufactured in the United States of America. Like the Class 25 locomotive, it had roller bearing axle boxes on all wheels, but not on the crank-pins, with cannon boxes on all axles except those of the inner pony trucks, which had outside bearings. It had a U-shaped foundation ring welded to the inner and outer firebox bottom edges and an all welded firebox. The engine units also had "Commonwealth" cast steel type frames.[1][3][4][5]

The boiler had an inspection manhole, fitted to the top of the boiler behind the dome. The locomotive was superheated, with a mechanical stoker and Walschaerts valve gear. It could negotiate curves of 275 feet (84 metres) radius with a gauge widening of not more than 0.75 inches (19 millimetres) and a superelevation of 4.5 inches (114 millimetres).[1][3]

Service

South African Railways

The one hundred and twenty locomotives of this class made it the most numerous Garratt class in the world. The Class GMA and Class GMAM saw service on main and secondary lines in many parts of South Africa. Prior to electrification, a number were employed in Transvaal on the Komatipoort line across the pass between Waterval Onder and Waterval Boven, and also on the coal line from Witbank to Germiston and the line from Krugersdorp via Zeerust to Mafeking.[1][3][4][5]

In Natal, the bulk of the Class was based at Pietermaritzburg, from where they worked most trains on the two heavily graded branchlines to Greytown and Franklin. Others worked on the Natal North Coast line between Stanger and Empangeni, while some assisted the Class GL on the coal line between Vryheid and Glencoe.[1][3][4][5]

The Cape Western system’s locomotives were stationed at Worcester, from where they worked the old New Cape Central Railway (NCCR) line via Riversdale to Mosselbaai until it was dieselised. Between 1981 and 1984 a number were allocated to the Cape Northern system to work the line from Vryburg to Mafeking, where they largely replaced the Class 19D locomotives that had earlier dominated on this line. This turned out to be their last term in mainline service, since they were replaced by Class 25NC locomotives in 1984 when the line was relaid with heavier rail.[4][5]

Most of the Class was then allocated to the Cape Midland system, with most of them initially stationed at Voorbaai where, in 1984, they replaced the Class GEA on trains from Mosselbaai to Riversdale and across the Montagu Pass to Oudtshoorn. Their allocation was later extended to the sheds at Sydenham in Port Elizabeth, Rosmead, Klipplaat and Graaff Reinet, with the result that they worked most of the trains over the route from Port Elizabeth to Rosmead via Klipplaat and across the Lootsberg Pass from Graaff Reinet. Towards the end of their service lives, the Eastern Transvaal system still had an allocation of them, where locomotives from the Waterval Boven and Breyten sheds worked the line down to Vryheid in Natal.[4][5]

They were the last class of Garratt to remain in service with the SAR. All but three were withdrawn from service by April 1988 and those three were also retired shortly afterwards.[3][4]

Zimbabwe and Mozambique

GMAM no. 4065 with raised coal bunker sides at Bulawayo Locoshed, 15 April 1980

During the period from August 1979 to September 1981 altogether 26 locomotives of the Class were hired to Zimbabwe-Rhodesia, but not all at the same time since they were rotated with Capital Park in Pretoria as their nominal home for the occasions when they had to return to South Africa for major repairs. On the Rhodesia Railways (RR), later the National Railways of Zimbabwe (NRZ), they worked from Bulawayo to Gwelo and to Wankie and beyond to Victoria Falls. Six of these locomotives were loaned by RR to the Caminhos de Ferro de Moçambique (CFM) for a short while to work the CFM Centro line from Beira to Umtali in Zimbabwe.[4][5][11][12][13]

In Zimbabwe these locomotives normally worked chimney first with the additional water tank at the rear. Since the Rhodesian bush war was still ongoing in 1979, the locomotives were equipped with armour plating around the cab. This obscured the number plates and the numbers were then usually stencilled on the cabsides. The Class GMAM was similar in size with a similar coal capacity to the Rhodesia Railways 20th class 4-8-2+2-8-4 Garratt, but it had a voracious appetite for coal and frequently ran low on fuel, with the result that trains often had to be dumped. In an attempt to solve this problem, RR extended the height of the Class GMAM's coal bunker by a foot to increase the capacity.[11][12][13]

Industrial and private

REGM R12 Number plate, ex SAR no. 4136

Several locomotives of the class were sold into industrial service and some later ended in preservation in private ownership. The majority went to the Randfontein Estates Gold Mining Company (REGM), while two were sold to the Hotham Valley Railway in Western Australia where they were to haul tourists in ex SAR passenger coaches. The locomotives, however, never left South Africa.[4][14]

Illustration

The main picture shows Class GMAM no. 4079 "Lindie Lou" turning around on the triangle at Capital Park, Pretoria on 30 September 2006. The following pictures illustrate the locomotive in service and in preservation.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 110–113. ISBN 978-0-7153-5427-8.
  2. ↑ South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  3. 1 2 3 4 5 6 7 Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 95–96. ISBN 0869772112.
  4. 1 2 3 4 5 6 7 8 9 10 11 Durrant, A E (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. pp. 115–117. ISBN 0715386387.
  5. 1 2 3 4 5 6 7 8 9 Durrant, A.E. (1981). Garratt Locomotives of the World. David & Charles. pp. 131-135. ISBN 0-7153-7641-1.
  6. 1 2 3 4 Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives from Other Builders, retrieved 10 November 2012
  7. 1 2 3 Henschel-Lieferliste (Henschel & Son works list), compiled by Dietmar Stresow
  8. 1 2 3 Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives produced by Beyer, Peacock, retrieved 10 November 2012
  9. 1 2 3 North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  10. 1 2 3 North British Locomotive Co. (from J. Lambert)
  11. 1 2 Pattison, R.G. (2005). Thundering Smoke, (1st ed.). Ilminster, Somerset: Sable Publishing House. pp. 127-130. ISBN 0-9549488-1-5.
  12. 1 2 Durrant, A.E. (1997). The Smoke that Thunders, (1st ed.). Harare: African Publishing Group. ISBN 1-77901-134-2.
  13. 1 2 Hamer, E.D. (2001). Locomotives Zimbabwe and Botswana, (1st ed.). Malmö: Frank Stenvalls Förlag. pp. 60-61. ISBN 91-7266-152-6.
  14. ↑ 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. pp. 29–30.

External links

External video
South African Steam - Garratts at Randfontein Estates Gold Mine 1994-1995. (30.16 minutes)
Wikimedia Commons has media related to South African Class GMA (4-8-2+2-8-4).
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