South African Class 25NC 4-8-4
Encyclopedia
Between 1953 and 1955 the South African Railways placed fifty Class 25NC steam locomotive
s with a 4-8-4
wheel arrangement in service. The Class 25NC is the non condensing version of the Class 25
condensing locomotive, of which ninety were placed in service at the same time. Between 1973 and 1980 all but three of the ninety Class 25 condensing locomotives were converted to non condensing locomotives and also classified as Class 25NC.
of Kassel in Germany. Between 1953 and 1955 eleven Class 25NC locomotives, numbers 3401 to 3411, were built by the North British Locomotive Company
(NBL) and thirty-nine, numbers 3412 to 3450, by Henschel.
Ninety Class 25 condensing locomotives were built as part of the same order, one by Henschel and the rest by NBL. The condensing apparatus for the engine and the condensing tender was designed and patented by Henschel.
The crossheads, of the Alligator type, were split on the vertical centre line and clamped on to the end of the piston rods, which had three coned rings engaging in grooves in the crossheads. The coupling rods differed from the usual in the provision of three independent rods, thereby doing away with four knuckle joints
and pins.
to Klerksdorp. Until the Welverdiend electrification was extended to Klerksdorp, they worked through to Welverdiend as well. In later years they also worked from Kimberley via Bloemfontein
to Harrismith
in the Free State
, and some joined the Class 25 condensers on the line from De Aar via Beaufort West
to Touws River
.
When the line south from De Aar was dieselised between 1973 and 1974, the Class 25 condensers working there were moved north to work the section from De Aar to Kimberley, where they replaced twenty-two Class 25NCs that were then relocated to Bethlehem
in the Free State. From 1982 Class 25NCs also replaced Class 19Ds
and Class GMAM
Garratts on the line from Warrenton
via Vryburg to Mafikeng
.
In the process their Type CZ condensing tenders were also rebuilt to ordinary coal-and-water tenders by removing the condensing radiators and roof fans and replacing it with a massive water tank. Since the Type CZ tenders were built on single cast steel main frames, it was impractical to attempt to shorten them, which resulted in the rebuilt Type CZ tenders with their long round topped water tanks. Locomotives with these rebuilt tenders were soon nicknamed "Worshond" (Sausage dog or Dachshund).
in Cape Town
. The primary objectives of the project were to improve the combustion and steaming rate, to reduce the emission of wasteful black smoke and to overcome the problem of clinkering.
This was achieved by the use of a Gas Producer Combustion System (GPCS) which relies on the gasification of coal on a low temperature firebed so that the gases are then fully burnt above the firebed. These extensive modifications justified reclassification and the locomotive became the first and only Class 26, although the locomotive’s original Class 25NC number 3450 was retained.
on 4 July 1999.
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
s with a 4-8-4
4-8-4
Under the Whyte notation classification of steam locomotives, 4-8-4 represents the wheel arrangement of four leading wheels on two axles , eight powered and coupled driving wheels on four axles, and four trailing wheels on two axles .Other equivalent classifications are:UIC classification: 2D2...
wheel arrangement in service. The Class 25NC is the non condensing version of the Class 25
South African Class 25 4-8-4
Between 1953 and 1955 the South African Railways placed ninety Class 25 condensing steam locomotives with a 4-8-4 Northern wheel arrangement in service...
condensing locomotive, of which ninety were placed in service at the same time. Between 1973 and 1980 all but three of the ninety Class 25 condensing locomotives were converted to non condensing locomotives and also classified as Class 25NC.
Manufacturers
The Class 25NC non condensing and Class 25 condensing 4-8-4 steam locomotives were designed by the South African Railways (SAR) in conjunction with Henschel and SonHenschel & Son
Henschel & Son was a German company, situated in Kassel, best known during the 20th century as a maker of transportation equipment, including locomotives, trucks, buses and trolleybuses, and armoured fighting vehicles and weapons....
of Kassel in Germany. Between 1953 and 1955 eleven Class 25NC locomotives, numbers 3401 to 3411, were built by the North British Locomotive Company
North British Locomotive Company
The North British Locomotive Company was created in 1903 through the merger of three Glasgow locomotive manufacturing companies; Sharp Stewart and Company , Neilson, Reid and Company and Dübs and Company , creating the largest locomotive manufacturing company in Europe.Its main factories were...
(NBL) and thirty-nine, numbers 3412 to 3450, by Henschel.
Characteristics
The Class 25NC had Walschaerts valve gear and roller bearings were used throughout, including on the three-axle tender bogies, the coupling and connecting rods as well as the crosshead gudgeon pins, while the locomotive’s leading bogies and drivers had Cannon-type axle boxes. The cylinders and underframes were cast in one piece, while the steel cylinders and steam chests were fitted with cast iron liners. The tender underframe was also a one piece steel casting. Being entirely mounted on roller bearings, very little effort was required to move these locomotives.Ninety Class 25 condensing locomotives were built as part of the same order, one by Henschel and the rest by NBL. The condensing apparatus for the engine and the condensing tender was designed and patented by Henschel.
The crossheads, of the Alligator type, were split on the vertical centre line and clamped on to the end of the piston rods, which had three coned rings engaging in grooves in the crossheads. The coupling rods differed from the usual in the provision of three independent rods, thereby doing away with four knuckle joints
Knuckle joint (mechanical)
A knuckle joint is used to connect the two rods which are under the tensile load, when there is requirement of small amount of flexibility or angular moment is necessary. There is always axial or linear line of action of load....
and pins.
Teething troubles
Soon after being placed in service, however, problems were experienced with connecting rods failing, big end bearings breaking up as well as cracks developing in the motion girder of the Alligator crossheads. After investigations by SAR engineers, with assistance from the South African Council for Scientific and Industrial Research (CSIR), the crossheads, slide bars and coupling rods were modified, with the crossheads converted to the multiple-bearing type with single guide bars, while the three independent coupling rods were replaced with the more conventional single coupling rod with knuckle joints.Service
The Class 25NC initially served on the unelectrified main lines from De Aar via KimberleyKimberley, Northern Cape
Kimberley is a city in South Africa, and the capital of the Northern Cape. It is located near the confluence of the Vaal and Orange Rivers. The town has considerable historical significance due its diamond mining past and siege during the Second Boer War...
to Klerksdorp. Until the Welverdiend electrification was extended to Klerksdorp, they worked through to Welverdiend as well. In later years they also worked from Kimberley via Bloemfontein
Bloemfontein
Bloemfontein is the capital city of the Free State Province of South Africa; and, as the judicial capital of the nation, one of South Africa's three national capitals – the other two being Cape Town, the legislative capital, and Pretoria, the administrative capital.Bloemfontein is popularly and...
to Harrismith
Harrismith
Harrismith, named after Sir Harry Smith, is a large town in the Free State province of South Africa, situated on the N3 highway approximately midway between Johannesburg, about 300 km north-east, and Durban. The town is at the junction with the N5 highway, which continues west towards the...
in the Free State
Free State
The Free State is a province of South Africa. Its capital is Bloemfontein, which is also South Africa's judicial capital. Its historical origins lie in the Orange Free State Boer republic and later Orange Free State Province. The current borders of the province date from 1994 when the Bantustans...
, and some joined the Class 25 condensers on the line from De Aar via Beaufort West
Beaufort West
Beaufort West is a town in the Western Cape province in South Africa. It is the largest town in the arid Great Karoo region, and forms part of the Beaufort West Local Municipality, with 37 000 inhabitants in 2001....
to Touws River
Touws River (town)
Touws River is a small railway town of 6,800 people in the Western Cape province of South Africa. It is located on the river of the same name, about north-east of Cape Town.-History:...
.
When the line south from De Aar was dieselised between 1973 and 1974, the Class 25 condensers working there were moved north to work the section from De Aar to Kimberley, where they replaced twenty-two Class 25NCs that were then relocated to Bethlehem
Bethlehem, Free State
Bethlehem is a town in the eastern Free State province of South Africa that is situated on the Liebenbergs river along a fertile valley just south of the Rooiberg Mountains on the N5 highway....
in the Free State. From 1982 Class 25NCs also replaced Class 19Ds
South African Class 19D 4-8-2
Between 1937 and 1949 the South African Railways placed two hundred and thirty-five Class 19D steam locomotives wirh a 4-8-2 Mountain wheel arrangement in service...
and Class GMAM
South African Class GMA 4-8-2+2-8-4
Between 1954 and 1958 the South African Railways placed one hundred and twenty Class GMA branch line and Class GMAM main line Garratt articulated steam locomotives with a 4-8-2+2-8-4 "Double Mountain" wheel arrangement in service...
Garratts on the line from Warrenton
Warrenton, Northern Cape
Warrenton is an agricultural town with a population of 25,100 situated in the Vaalharts Irrigation Scheme on the banks of the Vaal River in the Northern Cape Province of South Africa....
via Vryburg to Mafikeng
Mafikeng
Mahikeng – formerly legally, but still commonly known as Mafikeng – is the capital city of the North-West Province of South Africa. It is best known internationally for the Siege of Mafeking, the most famous engagement of the Second Boer War.Located on South Africa's border with Botswana, it is ...
.
Class 25 reclassification
Between 1973 and 1980 all but three of the ninety Class 25 condensers were converted to non condensing locomotives and reclassified to Class 25NC, the exceptions being numbers 3451, 3511 and 3540. Their number plates were copied and recast with the additional "NC" for "Non Condensing" squeezed in next to the existing "25", which resulted in a lopsided class indication on their plates. Locomotives with all four characters neatly in line and centred are therefore usually identifiable as original Class 25NCs.In the process their Type CZ condensing tenders were also rebuilt to ordinary coal-and-water tenders by removing the condensing radiators and roof fans and replacing it with a massive water tank. Since the Type CZ tenders were built on single cast steel main frames, it was impractical to attempt to shorten them, which resulted in the rebuilt Type CZ tenders with their long round topped water tanks. Locomotives with these rebuilt tenders were soon nicknamed "Worshond" (Sausage dog or Dachshund).
The Red Devil
Between 1979 and 1981 number 3450, the last Class 25NC to be built, was rebuilt to the sole Class 26, the "Red Devil", at the SAR workshops at Salt RiverSalt River, Cape Town
Salt River is a mainly industrial suburb of Cape Town located near Table Bay to the east of the city. It is named after a river of the same name, this being a continuation of the Black River. The name Salt River is a translation of the Dutch "Soutrivier"...
in Cape Town
Cape Town
Cape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
. The primary objectives of the project were to improve the combustion and steaming rate, to reduce the emission of wasteful black smoke and to overcome the problem of clinkering.
This was achieved by the use of a Gas Producer Combustion System (GPCS) which relies on the gasification of coal on a low temperature firebed so that the gases are then fully burnt above the firebed. These extensive modifications justified reclassification and the locomotive became the first and only Class 26, although the locomotive’s original Class 25NC number 3450 was retained.
Gallery
The main picture shows 3410 at Sannaspos in the Free StateFree State
The Free State is a province of South Africa. Its capital is Bloemfontein, which is also South Africa's judicial capital. Its historical origins lie in the Orange Free State Boer republic and later Orange Free State Province. The current borders of the province date from 1994 when the Bantustans...
on 4 July 1999.
See also
- South African Class 25 4-8-4South African Class 25 4-8-4Between 1953 and 1955 the South African Railways placed ninety Class 25 condensing steam locomotives with a 4-8-4 Northern wheel arrangement in service...
- South African Class 26 4-8-4
- Tender locomotive numbering and classification
- The 4-8-4 "Northern"
- List of South African locomotive classes