South African Railways GL class Garratt
Encyclopedia
During 1929 and 1930 the South African Railways placed eight Class GL Garratt articulated steam locomotives with a 4-8-2+2-8-4
"Double Mountain" wheel arrangement in service. Constructed at Beyer, Peacock and Company's Gorton
Foundry, they were originally designed to work on the Durban to Cato Ridge section of the Natal main Line. The Class GL was eventually displaced to the route between Glencoe and Vryheid, before spending their final working years operating on the line from Stanger to Empangeni.
. The old Natal main line had gradients of 1 in 30, whilst the newer line, relocated to provide an easier route, still had 38 miles (61 km) of near-uninterrupted 1 in 66 gradients. Moreover, the tight curvature of the line, with curves of as little as 275 feet (84 m) radius, precluded the use of large, long wheelbased rigid locomotives and restricted their length to a coupled wheelbase of 9 feet (2.7 m). These factors, combined with ever-increasing train weights, ensured that the line quickly became a bottleneck.
The decision to electrify
the line from Glencoe Junction to Durban had been taken in 1914, coincidentally the year in which the South African Railways (SAR) ordered its first Cape gauge
Garratt, the Class GA 2-6-0+0-6-2
. Electrification was placed in abeyance, along with the delivery of the Class GA, until the war’s end.
Despite this delay, the process of electrification began in earnest in 1922, and by 1926 full electrified haulage had been instituted between Glencoe and Pietermaritzburg, with consists of three electric locomotive
s being used on the heaviest freights. These trains were then hauled onward to Durban by a pair of Class 14 4-8-2
locomotives.
Meanwhile, the success of the Class GA Garratt, which was approximately equivalent in power output to two Class 14 locomotives, in proving the basic suitability of the Garratt design for South African conditions, coupled with the economies in crew, fuel and water consumption it offered, provided a healthy incentive for the SAR to consider a new Garratt class for use on the Natal main Line. The aim was to eliminate double-heading
as a regular practice, with such a locomotive to be equivalent to three of the Class 1E
electric locomotives that were then in use, or two Class 14 steam locomotives.
(CME) of the SAR from 1922 to 1929, prepared the specifications and awarded the contract for the construction of these locomotives, the Class GL, to Beyer, Peacock and Company
(BP). The design was to be approximately equal to two Class 14 locomotives in power output, with a maximum permitted axle loading of 18 long tons (18 t) owing to the use of 80 lb/yd rail on both sections of the main line, and a maximum all-up weight of 215 long tons (218 t).
Since these locomotives would be some 48% larger and more powerful than any previously employed on the SAR and up to twice the rail gauge
in width, the initial order was for two prototype locomotives only, with more to follow should they prove successful. They were delivered in September 1929 and were erected in the Durban shops, numbered 2350 and 2351, and placed in service in October. So successful did they prove to be that the remaining six locomotives were quickly ordered, for delivery in 1930 and numbered 2352 to 2357.
were 5 inches (127 mm) thick cut bar frames. On the SAR the bar frame had only been employed previously on the German-built Class GCA 2-6-2+2-6-2
Garratt.
s, which stabilised the locomotive by reducing to a minimum any vertical forces at the crosshead. This method of design became the standard on most Beyer-Garratts thereafter.
connecting the boiler
framing to the engine unit was spherical, with its alignment controlled by sprung rollers. The rear pivot was of the normal Beyer, Peacock flat adjustable type.
, which had an inside diameter of 7 feet (2.134 m), used a top feed and contained 263 small and 50 large tubes, plus superheater
flues of 1.5 inches (38.1 mm) diameter, while the round-top firebox was fired by a duplex mechanical stoker and contained two Nicholson thermic syphon
s and two arch tubes. Beyer, Peacock estimated the Class GL locomotive’s economical coal consumption rate at 3.5 long tons (4 t) per hour.
The Class GL made use of Beyer, Peacock’s standard lever-actuated Sterling-type steam-operated power reverser and a Pyle National Company turbo-generator, along with a rocking grate and self-cleaning hopper ashpan with water and steam sprayers to dampen down the ash, preventing it from entering axle boxes, motion areas and other friction-sensitive places.
powered fan blower to supply fresh air to the cab, sucked from ahead of the chimney, in deference to the almost 2 miles (3 km) of tunnels to be found on this difficult section of the line. This proved less than satisfactory, as did the smoke deflecting cowls over the chimneys of the second batch of locomotives. Since Garratts are designed to be bi-directional, the problem was eventually solved by simply running them with the chimney trailing on the ascending legs of the tunneled routes.
This suggested that the Class GL had still more to give, a suggestion confirmed on the following day’s testing when a load of 1205 long tons (1,224 t) was hauled over the same stretch of track. It was as a result of these tests that the further six Class GL locomotives were ordered for delivery in 1930.
The Class GLs were eventually marshalled to standard loads of between 950 and 1000 LT (965.2 and 1,016.1 t), despite having shown themselves capable of greater loads, in order to correspond with the load that could be hauled by a consist of three electric locomotives. Apart from demonstrating the Class GL’s prodigious power and capacity for hauling heavy trains, these tests also showed that their running qualities were exceptional, being smooth and free-running machines. In many ways, the Class GL set a design standard that was followed later in the Class GM
, Class GMAM
and Class GO
.
From Glencoe
the Class GL was then transferred to work the line between Stanger and Empangeni. However, since the loads on this route did not fully justify the use of the mighty GL while their great weight and high axle loading restricted them to main lines laid with heavy rail, they were eventually replaced by less powerful, more modern and more economical Class GMAM
locomotives. Though briefly considered, somewhat improbably, as hump shunters at Bloemfontein, the Class GL had outlasted its use and, after some forty-two years of working the most difficult terrain on the SAR, they were withdrawn from service in 1972.
. Number 2352, which waited at Germiston for some eight years before being shipped, shorn of around two hundred parts including its right-hand-side ashpan and much of its brick arch, resides at the Museum of Science and Industry in Manchester
.
4-8-2+2-8-4
A 4-8-2+2-8-4, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is an articulated type used on Garratt locomotives....
"Double Mountain" wheel arrangement in service. Constructed at Beyer, Peacock and Company's Gorton
Gorton
Gorton is an area of the city of Manchester, in North West England. It is located to the southeast of Manchester city centre. Neighbouring areas include Longsight and Levenshulme....
Foundry, they were originally designed to work on the Durban to Cato Ridge section of the Natal main Line. The Class GL was eventually displaced to the route between Glencoe and Vryheid, before spending their final working years operating on the line from Stanger to Empangeni.
Genesis
The Class GL had its origin in the steady increase in loads experienced by the Natal main line in the years prior to World War IWorld War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
. The old Natal main line had gradients of 1 in 30, whilst the newer line, relocated to provide an easier route, still had 38 miles (61 km) of near-uninterrupted 1 in 66 gradients. Moreover, the tight curvature of the line, with curves of as little as 275 feet (84 m) radius, precluded the use of large, long wheelbased rigid locomotives and restricted their length to a coupled wheelbase of 9 feet (2.7 m). These factors, combined with ever-increasing train weights, ensured that the line quickly became a bottleneck.
The decision to electrify
Railway electrification system
A railway electrification system supplies electrical energy to railway locomotives and multiple units as well as trams so that they can operate without having an on-board prime mover. There are several different electrification systems in use throughout the world...
the line from Glencoe Junction to Durban had been taken in 1914, coincidentally the year in which the South African Railways (SAR) ordered its first Cape gauge
Cape gauge
Cape gauge is a track gauge of between the inside of the rail heads and is classified as narrow gauge. It has installations of around .The gauge was first used by Norwegian engineer Carl Abraham Pihl and the first line was opened in 1862.- Nomenclature :...
Garratt, the Class GA 2-6-0+0-6-2
South African Class GA 2-6-0+0-6-2
In February 1921 the South African Railways placed a single experimental Class GA Garratt articulated steam locomotive with a 2-6-0+0-6-2 wheel arrangement in service...
. Electrification was placed in abeyance, along with the delivery of the Class GA, until the war’s end.
Despite this delay, the process of electrification began in earnest in 1922, and by 1926 full electrified haulage had been instituted between Glencoe and Pietermaritzburg, with consists of three electric locomotive
Electric locomotive
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or an on-board energy storage device...
s being used on the heaviest freights. These trains were then hauled onward to Durban by a pair of Class 14 4-8-2
South African Class 14 4-8-2
Between 1913 and 1915 the South African Railways placed forty-five Class 14 steam locomotives with a 4-8-2 Mountain wheel arrangement in service.-Manufacturer:...
locomotives.
Meanwhile, the success of the Class GA Garratt, which was approximately equivalent in power output to two Class 14 locomotives, in proving the basic suitability of the Garratt design for South African conditions, coupled with the economies in crew, fuel and water consumption it offered, provided a healthy incentive for the SAR to consider a new Garratt class for use on the Natal main Line. The aim was to eliminate double-heading
Double-heading
In railroad terminology, double-heading or double heading indicates the use of two locomotives at the front of a train, each operated individually by its own crew. The practice of triple-heading involves the use of three locomotives....
as a regular practice, with such a locomotive to be equivalent to three of the Class 1E
South African Class 1E
Between 1925 and 1945 the South African Railways placed altogether one hundred and seventy-two Class 1E electric locomotives in service, spread over seven orders.-Manufacturers:...
electric locomotives that were then in use, or two Class 14 steam locomotives.
Manufacturer
Colonel F.R. Collins, the Chief Mechanical EngineerChief Mechanical Engineer
Chief Mechanical Engineer and Locomotive Superintendent are titles applied by British, Australian, and New Zealand railway companies to the person ultimately responsible to the board of the company for the building and maintaining of the locomotives and rolling stock...
(CME) of the SAR from 1922 to 1929, prepared the specifications and awarded the contract for the construction of these locomotives, the Class GL, to Beyer, Peacock and Company
Beyer, Peacock and Company
Beyer, Peacock and Company was an English railway Locomotive manufacturer with a factory in Gorton, Manchester. Founded by Charles Beyer and Richard Peacock, it traded from 1854 until 1966...
(BP). The design was to be approximately equal to two Class 14 locomotives in power output, with a maximum permitted axle loading of 18 long tons (18 t) owing to the use of 80 lb/yd rail on both sections of the main line, and a maximum all-up weight of 215 long tons (218 t).
Since these locomotives would be some 48% larger and more powerful than any previously employed on the SAR and up to twice the rail gauge
Rail gauge
Track gauge or rail gauge is the distance between the inner sides of the heads of the two load bearing rails that make up a single railway line. Sixty percent of the world's railways use a standard gauge of . Wider gauges are called broad gauge; smaller gauges, narrow gauge. Break-of-gauge refers...
in width, the initial order was for two prototype locomotives only, with more to follow should they prove successful. They were delivered in September 1929 and were erected in the Durban shops, numbered 2350 and 2351, and placed in service in October. So successful did they prove to be that the remaining six locomotives were quickly ordered, for delivery in 1930 and numbered 2352 to 2357.
Design
The Class GL embodied comparatively few features of any particular novelty. Instead, they were designed to make the best possible use of existing technologies to produce a locomotive of great power, efficiency and reliability. Their all-up weight of 214.1 long tons (218 t), coupled with their 18 long tons (18 t) axle loading, was almost exactly within the limits laid down by the SAR and was considered by Lionel Wiener, author of Articulated Locomotives, to show "such mastery in general and detail design that we have pleasure on congratulating Messrs. Beyer, Peacock & Co. on this achievement."Frame
The main framesLocomotive frame
A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind...
were 5 inches (127 mm) thick cut bar frames. On the SAR the bar frame had only been employed previously on the German-built Class GCA 2-6-2+2-6-2
South African Class GCA 2-6-2+2-6-2
In 1927 the South African Railways placed thirteen Class GCA Garratt articulated steam locomotives with a 2-6-2+2-6-2 wheel arrangement in branch line service...
Garratt.
Valves and cylinders
The valves were modern straight-ported types with long-lap, long-travel valves, used for the first time in a South African Garratt, making the Class GL very free-running and more efficient than its predecessors. The cylinders, of the same bore and stroke as those of the Class 14, drove the third coupled axle using long connecting rodConnecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....
s, which stabilised the locomotive by reducing to a minimum any vertical forces at the crosshead. This method of design became the standard on most Beyer-Garratts thereafter.
Pivots
In order to allow for the tight curves, including 300 feet (91 m) radius bends with 4.5 inches (114.3 mm) superelevation lacking any intermediate tangent, and the steep, twisting nature of the line, the front pivot bearingBearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
connecting the boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...
framing to the engine unit was spherical, with its alignment controlled by sprung rollers. The rear pivot was of the normal Beyer, Peacock flat adjustable type.
Boiler and firebox
The boilerBoiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...
, which had an inside diameter of 7 feet (2.134 m), used a top feed and contained 263 small and 50 large tubes, plus superheater
Superheater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...
flues of 1.5 inches (38.1 mm) diameter, while the round-top firebox was fired by a duplex mechanical stoker and contained two Nicholson thermic syphon
Thermic syphon
Thermic siphons are heat-exchanging elements in the firebox or combustion chamber of some steam boiler and steam locomotive designs. As they are directly exposed to the radiant heat of combustion, they have a high evaporative capacity relative to their size...
s and two arch tubes. Beyer, Peacock estimated the Class GL locomotive’s economical coal consumption rate at 3.5 long tons (4 t) per hour.
The Class GL made use of Beyer, Peacock’s standard lever-actuated Sterling-type steam-operated power reverser and a Pyle National Company turbo-generator, along with a rocking grate and self-cleaning hopper ashpan with water and steam sprayers to dampen down the ash, preventing it from entering axle boxes, motion areas and other friction-sensitive places.
Crew comfort
Crew comfort was also considered. They were equipped with a "Sturtevant" steam turbineSteam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....
powered fan blower to supply fresh air to the cab, sucked from ahead of the chimney, in deference to the almost 2 miles (3 km) of tunnels to be found on this difficult section of the line. This proved less than satisfactory, as did the smoke deflecting cowls over the chimneys of the second batch of locomotives. Since Garratts are designed to be bi-directional, the problem was eventually solved by simply running them with the chimney trailing on the ascending legs of the tunneled routes.
Trials
Their tractive effort of 78650 pound-forces (349.9 kN) at 75% boiler pressure made them the most powerful steam locomotives to be placed in service anywhere in the Southern Hemisphere at the time and attained the objective of constructing a locomotive to approximately equal the power output of two Class 14 locomotives. On their first test run and despite the cut-off on these locomotives being limited to 65%, 1117 long tons (1,135 t) were hauled from Durban to Cato Ridge in 163 minutes, as against 500 long tons (508 t) in 184 minutes for a Class 14. Moreover, this was performed on half throttle (i.e. in first valve) and with the cut-off set at 45%.This suggested that the Class GL had still more to give, a suggestion confirmed on the following day’s testing when a load of 1205 long tons (1,224 t) was hauled over the same stretch of track. It was as a result of these tests that the further six Class GL locomotives were ordered for delivery in 1930.
The Class GLs were eventually marshalled to standard loads of between 950 and 1000 LT (965.2 and 1,016.1 t), despite having shown themselves capable of greater loads, in order to correspond with the load that could be hauled by a consist of three electric locomotives. Apart from demonstrating the Class GL’s prodigious power and capacity for hauling heavy trains, these tests also showed that their running qualities were exceptional, being smooth and free-running machines. In many ways, the Class GL set a design standard that was followed later in the Class GM
South African Class GM 4-8-2+2-8-4
During 1938 and 1939 the South African Railways placed sixteen Class GM Garratt articulated steam locomotives with a 4-8-2+2-8-4 "Double Mountain" wheel arrangement in goods train service.-Manufacturer:...
, 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...
and Class GO
South African Class GO 4-8-2+2-8-4
In 1954 the South African Railways placed twenty-five Class GO light branch line Garratt articulated steam locomotives with a 4-8-2+2-8-4 "Double Mountain" wheel arrangement in service.-Manufacturer:...
.
Service
Upon completion of the electrification project between Durban and Pietermaritzburg in 1938, the eight locomotives were transferred from the Durban section to the gruelling run between Glencoe and Vryheid, with the latter’s coal trains. This work entailed the regular haulage of 1200 long tons (1,219 t) up gradients of 1 in 50, taxing the Class GL even more heavily than the work for which it was designed. Despite this they maintained an effective service along this line until its electrification in 1968.From Glencoe
Glencoe, KwaZulu-Natal
Glencoe is situated in the Umzinyathi District District of KwaZulu-Natal, South Africa.The main economic activity in the area is coal mining while sheep and cattle ranching are also practiced.-History:...
the Class GL was then transferred to work the line between Stanger and Empangeni. However, since the loads on this route did not fully justify the use of the mighty GL while their great weight and high axle loading restricted them to main lines laid with heavy rail, they were eventually replaced by less powerful, more modern and more economical 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...
locomotives. Though briefly considered, somewhat improbably, as hump shunters at Bloemfontein, the Class GL had outlasted its use and, after some forty-two years of working the most difficult terrain on the SAR, they were withdrawn from service in 1972.
Preservation
Of the eight locomotives only two survived. Number 2351, named Princess Alice, is preserved at the Outeniqua Transport MuseumOuteniqua Transport Museum
The Outeniqua Transport Museum is a railway museum located in George, South Africa.- External links :* *...
. Number 2352, which waited at Germiston for some eight years before being shipped, shorn of around two hundred parts including its right-hand-side ashpan and much of its brick arch, resides at the Museum of Science and Industry in Manchester
Museum of Science and Industry in Manchester
The Museum of Science and Industry in Manchester, England, is a large museum devoted to the development of science, technology, and industry with emphasis on the city's achievements in these fields...
.
Gallery
The main picture shows Class GL 2351 "Princess Alice", circa 1930. The smoke deflecting cowl on the chimney was later removed.See also
- South African Class GA 2-6-0+0-6-2South African Class GA 2-6-0+0-6-2In February 1921 the South African Railways placed a single experimental Class GA Garratt articulated steam locomotive with a 2-6-0+0-6-2 wheel arrangement in service...
- South African Class GB 2-6-2+2-6-2South African Class GB 2-6-2+2-6-2In June 1921 the South African Railways placed a single experimental Class GB Garratt articulated steam locomotive with a 2-6-2+2-6-2 wheel arrangement in service...
- South African Class GC 2-6-2+2-6-2South African Class GC 2-6-2+2-6-2In 1924 and 1925 the South African Railways placed six Class GC Garratt articulated steam locomotives with a 2-6-2+2-6-2 wheel arrangement in branch line service.-Manufacturer:The first locomotive to be built to the specifications of Colonel F.R...
- South African Class GCA 2-6-2+2-6-2South African Class GCA 2-6-2+2-6-2In 1927 the South African Railways placed thirteen Class GCA Garratt articulated steam locomotives with a 2-6-2+2-6-2 wheel arrangement in branch line service...
- South African Class GD 2-6-2+2-6-2South African Class GD 2-6-2+2-6-2In 1925 the South African Railways placed four Class GD Garratt articulated locomotives with a 2-6-2+2-6-2 wheel arrangement in branch line service...
- South African Class GDA 2-6-2+2-6-2South African Class GDA 2-6-2+2-6-2In 1929 the South African Railways placed five Class GDA Garratt articulated locomotives with a 2-6-2+2-6-2 wheel arrangement in branch line service.-Manufacturer:...
- South African Class GE 2-8-2+2-8-2South African Class GE 2-8-2+2-8-2Between 1925 and 1931 the South African Railways placed eighteen Class GE Garratt articulated locomotives with a 2-8-2+2-8-2 wheel arrangement in service.-Manufacturer:...
- South African Class GEA 4-8-2+2-8-4South African Class GEA 4-8-2+2-8-4During 1946 and 1947 the South African Railways placed fifty Class GEA Garratt articulated steam locomotives with a 4-8-2+2-8-4 wheel arrangement in service.-Manufacturer:...
- South African Class GF 4-6-2+2-6-4South African Class GF 4-6-2+2-6-4In 1927 the South African Railways placed thirty-seven Class GF Garratt articulated steam locomotives with a 4-6-2+2-6-4 "Double Pacific" wheel arrangement in service. A further twenty-eight locomotives were delivered in 1928.-Manufacturers:...
- South African Class GG 2-6-2+2-6-2South African Class GG 2-6-2+2-6-2In 1925 the South African Railways placed a single Class GG Garratt articulated steam locomotive with a 2-6-2+2-6-2 "Double Prairie" wheel arrangement in fast main line passenger service.-Manufacturers:...
- South African Class GK 2-6-2+2-6-2South African Class GK 2-6-2+2-6-2In 1923 the New Cape Central Railway placed two Garratt articulated steam locomotives with a 2-6-2+2-6-2 "Double Prairie" wheel arrangement in service...
- South African Class GM 4-8-2+2-8-4South African Class GM 4-8-2+2-8-4During 1938 and 1939 the South African Railways placed sixteen Class GM Garratt articulated steam locomotives with a 4-8-2+2-8-4 "Double Mountain" wheel arrangement in goods train service.-Manufacturer:...
- South African Class GMA 4-8-2+2-8-4South African Class GMA 4-8-2+2-8-4Between 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...
- South African Class GO 4-8-2+2-8-4South African Class GO 4-8-2+2-8-4In 1954 the South African Railways placed twenty-five Class GO light branch line Garratt articulated steam locomotives with a 4-8-2+2-8-4 "Double Mountain" wheel arrangement in service.-Manufacturer:...
- The 4-8-2+2-8-4 "Double Mountain"
- Articulated locomotive numbering and classification
- List of South African locomotive classes