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It was against such a background that Herbert William Garratt (1864-1913), Inspecting Engineer for the New South Wales Government, brought to Beyer, Peacock the basic principle of locomotive articulation. which has since borne his name. The drawing for the patent specification, which was taken out by Garratt in 1907, shows a 2-4-0 + 0-4-2 engine with high-pressure cylinders at the outer ends of the bogies. Mr. Garratt’s overseas commitments and his sudden death on 25 September 1913 meant that most of the development of this design was carried out by Beyer, Peacock themselves. This firm considered building a 0-6-0 + 0-6-0 engine for its 1 ft 6ins gauge works system in order to demonstrate the principle, but in 1909 the Tasmanian Government ordered two for its 2ft gauge railways. Against Mr. Garratt’s advice, the specification called for a compound design and so the first Garratts (9954) had their cylinders at the inboard end of the bogies in order to keep as short as possible the steam pipe between the high and low pressure cylinders. Beyer Peacock brought the first of these engines back to this country soon after the Second World War, and on the closure of Gorton Foundry it was sold to the Festiniog Railway. Only one other Garratt was compounded, which was sent to the Burma Railway (1119) and all other Garratts had cylinders at the outer ends of the bogies. The next Garratt design was another narrow gauge engine, this time for the Darjeeling-Himelayan Railway (094). The line abounds in bends and steep gradients, and the engine was so long that sometimes the bogies were on curves going in different directions at the same time. This engine was prone to slipping and proved expensive in coal consumption, but it worked for over 40 years until it was withdrawn in 1953. Before 1914, Garratts had been sent to Western Australia Tasmania and to the Mogyana (0322) and San Paulo (0810) railways in Brazil. |
The First World War stopped all locomotive building and the works were switched to guns and munitions. Nothing could be done to further the reputation of the Garratt design until hostilities finished, when three different types (0941, 0942, 01060) for the South African Railways were completed in 1920. (01000 was 2ft gauge, 3ft 6ins being the normal S.A.R. gauge, and a development of this design was the last type of steam engine to be built at Gorton in 1958.) Trials of the first "GA" class (0941) against a Mallet illustrated the remarkable feature of the Garratt design. "It not only took a much greater load than the heavy main line engines, including a ‘Mallet’ engine against which it was tested, but its running times were better, and its water and coal consumption less" (from S.A.R. Report in 1921). The maintenance costs were expected to be lower because the Garratt boiler did not have to be worked to its limit. The greatest advantage of the Garratt was the freedom it gave for the drawing office to produce the best possible boiler design. With the boiler suspended between two power units, there was unrestricted space available for wide and deep fireboxes and barrels of large diameter. The East African Railways 59 class (11164) had a boiler 7ft 6 ins diameter on metre gauge, far larger than the boilers of engines on the 4ft 8 ins gauge of this country, where the loading gauge is so restricted. The grate area could be made very large as it was not hemmed in by wheels. One man could not stoke more than 50 sq.ft. of grate area, so the larger engines had mechanical stokers or oil firing. In 1931, Beyer, Peacock developed a rotary "self-trimming" bunker. Some of these were fitted to the Garratts built for the London Midland and Scottish Railway (1114) which worked coal trains to London. However, the "P" class with a grate area of 70 sq.ft. for the Bengal-Nagpur Railway (11113) carried two firemen and sometimes a third man to bring coal forward. Although two firemen were carried, the number of staff was reduced because these engines eliminated double-heading and banking. On the Benguela Railway (1155) in the Congo, some of the Garratts were wood-fired due to the difficulty of transporting other fuels, and these engines carried a crew of four to feed the logs forward continuously while the engines were working hard up the long gradients. |
Another feature which was fully exploited down the years until production ceased in 1958 was the feasibility of spreading the weight of the engine over a great many axles. When many of the railway lines were built in countries overseas, there was not sufficient capital, nor were the countries themselves far enough developed economically to justify a large investment in heavy engineering works. Often, therefore, light track was laid down on equally insubstantial foundations and bridges, while long sections of single line limited the number of trains that could be run. As traffic increased, the trains could not be lengthened because conventional engines had reached the limit of their power due to restrictions of axle loading. Alternative solutions were either double-heading longer trains or re-building and re-laying large parts of the lines to take heavier locomotives. Either method was expensive, but the Garratt provided a cheap answer. One boiler which needed only one crew could be placed on two power bogies with the result that the tractive effort could be doubled and the weight distributed over a large number of wheels. On the Sierra Leone Government Railway, the limit for conventional locomotives had been reached before 1926 owing to the very low figure of a 5 ton axle load. Three 2-6-2 + 2-6-2 Garratts (1111) were delivered in that year and comparative results were obtained from trains headed by a Garratt and trains double-headed by a tender engine and a tank engine. The Garratt showed a better performance all round. An outstanding example of a design for 50 lb. rail was introduced on the Sudan Railways in 1937 (1186), where the maximum axle load was restricted to 12.5 tons. As these lines traverse some of the world’s worst desert country, the greater part of which is waterless with temperatures reaching as high as 150 F in the sun, the maximum quantity of water had to be carried. Therefore a 4-6-4 + 4-6-4, the first engine with this wheel arrangement was evolved, and even then auxiliary water tanks were necessary on some sections where there was a distance of 150 miles without water. Instead of two engines, one Garratt could haul trains of 1,600 tons between Atbara and Wad Medani, a round trip of 600 miles. At the time of their introduction, these engines were the most powerful to operate on so tight a rail, but this design was soon enlarged for in 1939 a more powerful 4-8-4 + 4-8-4 was built for the Kenya & Uganda Railways (1198). Again, these engines were the first with this wheelbase, and they were used on the round trip from Nairobi to Kampala and back, a distance of 1,100 miles. A design built in 1938 for the South African Railways, who wanted a very powerful yet light engine, had most of the water carried in an auxiliary tender (1196). The hind unit of the engine carried only coal, while the front tank carried sufficient water for shunting purposes when the engine was detached from its train. |
In spite of the length or these engines, they were remarkably steady and light on the track. They took the curves better and had less tyre wear than conventional locomotives. For example, in 1912 two 4-4-2 + 2-4-4 engines (0303) were supplied to the Tasmanian Government for their 3ft 6ins gauge system. These engines had four cylinders on each bogie, and on a demonstration run one of them reached 55 miles per hour, a record for the Tasmanian Railways at the time. In 1935 the Society Franco-Belge de Materiel de Chemin de Fer, of Raismes (Nord) France, in conjunction with Beyer, Peacock, produced some Garratts for the Algerian section of the Paris, Lyon & Mediterranean Railway which were capable of reaching more than 75 m.p.h. Between Algiers and Oran (262 miles), where stretches of gradient equivalent to 1 in 45 occur, these engines hauled 466 tons in 5 hours 50 minutes, averaging 45 m.p.h., while previously anything over a 256 ton load was double-headed and took nine hours. Continual improvements and constant attention to design details made the Garratt engines very reliable and economical. In 1940, the Rhodesian Railway wanted an engine (1115) to haul 500 ton trains from Mafeking to Bulawayo, a distance of 484 miles with gradients at 1 in 80 through the Bechuanaland Protectorate where no servicing facilities existed. Speeds up to 50 m.p.h. were expected, so all the bogies had roller bearings and all the coupled wheels had grease lubrication. Although there were 48 main bearings on each of these locomotives, no hot bearings were experienced. Since there were triangles at each end of the line, these Garratts were exceptional in being turned at the end of each trip so that the valve gear was arranged for chimney first working and the front tanks slightly streamlined. They were considered to be the most economical engines on the railway. |
Something of the wide range of Garratt locomotives has already been indicated. The largest steam engine built in Europe was the 4-8-2 + 2-8-4 Garratt for the Russian Railways (1176). This weighed 262.5 tons in working order and produced 90,000 lb. tractive effort at 95% boiler pressure. It was built in 1932 with bar frames 5 ins thick, was 17ft 2ins high, and was tested in a temperature of -41 C, or 74 degrees of frost. Its nearest rival was the 3ft 6ins gauge "GL" Class (1141) for the South African Railways in 1929, producing 89,130 lb. tractive effort, which must remain the most powerful class of steam locomotive for this gauge in the world. The most powerful steam locomotive in Great Britain, the L.N.E.R. 2-8-0 + 0-8-2 (112) produced a mere 72,930 lb. tractive effort, but it could handle a 700 ton load up an incline of 1 in 40 without assistance. In 1927, two years after this, the L.M.S. ordered three (1114) and later 30 more 2-6-0 + 0-6-2 Garratts which had the same wheel and cylinder dimensions as the Horwich Moguls. A few smaller Garratts with 0-4-0 + 0-4-0 wheelbase were made for shunting duties at some industrial works in the UK, but most Garratt engines were sent overseas. They worked on the world’s highest standard gauge line through the Galera Tunnel on the Central Railway of Peru at 15,693 ft. (1174) and through Condor Station, 15,814 ft. on the metre gauge Antofagasta (Chili) & Bolivia Railway (1138). Special Garratts were built during the Second World War, and pride of place must go to a war order for the Burma Railways. From the date of receiving the official instruction, the designing of this 2-8-2 + 2-8-2 (11123), the purchasing of materials, and manufacture were completed and the first engine in steam within 118 days, four days ahead of programme. Tanks, shells and other munitions were produced at the works during the war in addition to railway locomotives. The last Garratts built by Beyer, Peacock were for the Tsumeb Corporation in 1958 (11188), but went to the 2ft gauge S.A.R. system as the Corporation changed its gauge. |