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South African Class A 4-8-2T
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South African Class A 4-8-2T
The South African Railways Class A 4-8-2T of 1888 is a steam locomotive class from the pre-Union era in the Colony of Natal.
In 1888, the Natal Government Railways placed the first five of its eventual one hundred Class D 4-8-2T steam locomotives in service. The last was delivered in 1899. They were the first locomotives in the world to be built with a 4-8-2 wheel arrangement, later to become known as the Mountain type. In 1912, when these locomotives were assimilated into the South African Railways, they were renumbered and designated Class A. In 1915, another two Class A locomotives were built from spare parts.
The Natal Government Railways (NGR) Class D 4-8-2 tank locomotive was designed by William Milne, the Locomotive Superintendent of the NGR from 1877 to 1896, and was built by Dübs and Company. The first 46 locomotives, with an operating boiler pressure of 140 pounds per square inch (965 kilopascals) and numbered in the range from 49 to 94, were placed in service during Milne's term. They proved to be such good engines that, when G.W. Reid took over as Locomotive Superintendent in 1896, he continued to place further orders for another 58, numbered in the range from 91 to 148, but with the boiler pressure increased to 160 pounds per square inch (1,103 kilopascals). These 100 locomotives, initially known on the NGR as the Dübs A, were delivered in ten batches by Dübs between 1888 and 1899.
As far as is known, the Dübs A locomotives were the first in the world to be designed and built with a 4-8-2 wheel arrangement, later to become known as the Mountain type.
The performance in service of the Dübs A was gradually improved by various modifications. New boilers were fitted as and when the originals needed replacement, with a working pressure of 160 pounds per square inch (1,103 kilopascals) instead of the as-delivered 140 pounds per square inch (965 kilopascals) of the first few batches. This increased their tractive effort at 75% boiler pressure from 16,340 pounds-force (72.7 kilonewtons) to 18,670 pounds-force (83.0 kilonewtons). The coal bunkers were also enlarged and the connecting rod big-ends were changed to the marine type to increase ground clearance.
Another modification was an extended smokebox on most locomotives, such as on NGR no. 87 depicted below. In the 1890s, some improvements to smokebox design took place. Extending the smokebox forward increased its volume. The increased amount of exhaust gases present in the smokebox had the effect of stabilising and improving the draught. The date of this improvement can be pinned to 1891 when the second batch of Michael Stephens' Cape Government Railways (CGR) 5th Class 4-6-0 locomotives with their lengthened smokeboxes entered service. This had such a profound effect on the boiler's steaming ability that virtually every locomotive on the CGR and NGR had their smokeboxes extended.
Beginning in 1905, after D.A. Hendrie took over from Reid as Locomotive Superintendent, these locomotives were gradually fitted with Belpaire fireboxes with wider firegrates. The flat-topped Belpaire firebox had the advantage of an increased area of the water-line at the hottest part of the boiler, together with increased steam space over the firebox. In order to accomplish this, Hendrie raised the boiler's pitch by 4+1⁄2 inches (114 millimetres) and cut away the frame under the firebox to accommodate the wider grates. The wider firebox required that the water tanks also had to be moved out and the opportunity was taken to enlarge the tanks. The cabs were also improved to offer the engine crew better protection, and new brass-capped chimneys replaced the original straight flared chimneys. These modified locomotives were known as the Improved Dübs A.
When a locomotive classification system was introduced on the NGR, the Dübs A locomotive family was designated Class D. The unmodified locomotives became the Class D1 while the modified locomotives with Belpaire fireboxes became the Class D2.
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South African Class A 4-8-2T
The South African Railways Class A 4-8-2T of 1888 is a steam locomotive class from the pre-Union era in the Colony of Natal.
In 1888, the Natal Government Railways placed the first five of its eventual one hundred Class D 4-8-2T steam locomotives in service. The last was delivered in 1899. They were the first locomotives in the world to be built with a 4-8-2 wheel arrangement, later to become known as the Mountain type. In 1912, when these locomotives were assimilated into the South African Railways, they were renumbered and designated Class A. In 1915, another two Class A locomotives were built from spare parts.
The Natal Government Railways (NGR) Class D 4-8-2 tank locomotive was designed by William Milne, the Locomotive Superintendent of the NGR from 1877 to 1896, and was built by Dübs and Company. The first 46 locomotives, with an operating boiler pressure of 140 pounds per square inch (965 kilopascals) and numbered in the range from 49 to 94, were placed in service during Milne's term. They proved to be such good engines that, when G.W. Reid took over as Locomotive Superintendent in 1896, he continued to place further orders for another 58, numbered in the range from 91 to 148, but with the boiler pressure increased to 160 pounds per square inch (1,103 kilopascals). These 100 locomotives, initially known on the NGR as the Dübs A, were delivered in ten batches by Dübs between 1888 and 1899.
As far as is known, the Dübs A locomotives were the first in the world to be designed and built with a 4-8-2 wheel arrangement, later to become known as the Mountain type.
The performance in service of the Dübs A was gradually improved by various modifications. New boilers were fitted as and when the originals needed replacement, with a working pressure of 160 pounds per square inch (1,103 kilopascals) instead of the as-delivered 140 pounds per square inch (965 kilopascals) of the first few batches. This increased their tractive effort at 75% boiler pressure from 16,340 pounds-force (72.7 kilonewtons) to 18,670 pounds-force (83.0 kilonewtons). The coal bunkers were also enlarged and the connecting rod big-ends were changed to the marine type to increase ground clearance.
Another modification was an extended smokebox on most locomotives, such as on NGR no. 87 depicted below. In the 1890s, some improvements to smokebox design took place. Extending the smokebox forward increased its volume. The increased amount of exhaust gases present in the smokebox had the effect of stabilising and improving the draught. The date of this improvement can be pinned to 1891 when the second batch of Michael Stephens' Cape Government Railways (CGR) 5th Class 4-6-0 locomotives with their lengthened smokeboxes entered service. This had such a profound effect on the boiler's steaming ability that virtually every locomotive on the CGR and NGR had their smokeboxes extended.
Beginning in 1905, after D.A. Hendrie took over from Reid as Locomotive Superintendent, these locomotives were gradually fitted with Belpaire fireboxes with wider firegrates. The flat-topped Belpaire firebox had the advantage of an increased area of the water-line at the hottest part of the boiler, together with increased steam space over the firebox. In order to accomplish this, Hendrie raised the boiler's pitch by 4+1⁄2 inches (114 millimetres) and cut away the frame under the firebox to accommodate the wider grates. The wider firebox required that the water tanks also had to be moved out and the opportunity was taken to enlarge the tanks. The cabs were also improved to offer the engine crew better protection, and new brass-capped chimneys replaced the original straight flared chimneys. These modified locomotives were known as the Improved Dübs A.
When a locomotive classification system was introduced on the NGR, the Dübs A locomotive family was designated Class D. The unmodified locomotives became the Class D1 while the modified locomotives with Belpaire fireboxes became the Class D2.
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