1.
South African Class 2 4-6-2
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The South African Railways Class 2 4-6-2 of 1905 was a steam locomotive from the pre-Union era in the Colony of Natal. In 1905, the Natal Government Railways placed two Class A steam locomotives with a 4-6-2 Pacific type wheel arrangement in service, in 1912, when these locomotives were assimilated into the South African Railways, they were renumbered and designated Class 2. In 1904, orders were placed with the North British Locomotive Company for two 4-6-2 Pacific type locomotives for the Natal Government Railways. They were designed by NGR Locomotive Superintendent D. A. Hendrie for passenger traffic on sections of the mainline between Ladysmith and Charlestown which did not have very severe gradients. When they were delivered and placed in early in 1905, they were designated the NGR Class A, also commonly known as the Hendrie A. The boiler of this Class was noted for its free steaming qualities, the engines used saturated steam, had Stephenson valve gear and were built on plate frames. The cylinders were inclined 1 in 18 and were arranged outside the plate frames, after these two engines, Hendrie adopted Walschaerts valve gear and outside valves on all his subsequent locomotive designs for its greater accessibility. The locomotives had Belpaire fireboxes with firebar rocking finger grates, with a bridle casting, the widening of the locomotive frame at the back end was accomplished by uniting the narrow front part of the frame and the wider rear part by the heavy steel casting. This method of widening the frames for the continued on the SAR until the general adoption of bar frames for mainline locomotives by 1927 rendered it no longer necessary. The two locomotives ran their first trials on 31 January and 3 March 1905 respectively, as intended, they were placed in service between Ladysmith and Charlestown and were shedded at Charlestown. They worked the trains on this section for many years. In 1912, these two Pacifics were renumbered 762 and 763 and designated Class 2 on the SAR and they were later transferred to the Witwatersrand for a short period, after which they worked on the Komatipoort-Waterval Boven section until they were withdrawn by 1936
2.
Whyte notation
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The notation counts the number of leading wheels, then the number of driving wheels, and finally the number of trailing wheels, groups of numbers being separated by dashes. Other classification schemes, like UIC classification and the French, Turkish and Swiss systems for steam locomotives, in the notation a locomotive with two leading axles in front, then three driving axles and then one trailing axle is classified as 4-6-2. Articulated locomotives such as Garratts, which are two locomotives joined by a common boiler, have a + between the arrangements of each engine. Thus a double Pacific type Garratt is a 4-6-2+2-6-4, for Garratt locomotives the + sign is used even when there are no intermediate unpowered wheels, e. g. the LMS Garratt 2-6-0+0-6-2. This is because the two units are more than just power bogies. They are complete engines, carrying fuel and water tanks, the + sign represents the bridge that links the two engines. Simpler articulated types such as Mallets, have a frame under a common boiler where there are no unpowered wheels between the sets of powered wheels. Typically, the frame is free to swing, whereas the rear frame is rigid with the boiler. Thus a Union Pacific Big Boy is a 4-8-8-4, four leading wheels, one group of eight driving wheels, another group of eight driving wheels and this numbering system is shared by duplex locomotives, which have powered wheel sets sharing a rigid frame. No suffix means a tender locomotive, T indicates a tank locomotive, in European practice, this is sometimes extended to indicate the type of tank locomotive, T means side tank, PT pannier tank, ST saddle tank, WT well tank. T+T means a tank locomotive that also has a tender, in Europe, the suffix R can signify rack or reversible, the latter being Bi-cabine locomotives used in France. The suffix F indicates a fireless locomotive, other suffixes have been used, including ng for narrow-gauge and CA or ca for compressed air. In Britain, small diesel and petrol locomotives are classified in the same way as steam locomotives. This may be followed by D for diesel or P for petrol, thus 0-6-0DE denotes a six-wheel diesel locomotive with electric transmission. Where the axles are coupled by chains or shafts or are individually driven, thus 4wPE indicates a four-wheel petrol locomotive with electric transmission. For large diesel locomotives the UIC classification is used, the main limitation of Whyte Notation is that it does not cover non-standard types such as Shay locomotives, which use geared trucks rather than driving wheels. The most commonly used system in Europe outside the United Kingdom is UIC classification, based on German practice, in American practice, most wheel arrangements in common use were given names, sometimes from the name of the first such locomotive built. For example, the 2-2-0 type arrangement is named Planet, after the 1830 locomotive on which it was first used, the most common wheel arrangements are listed below
3.
4-6-2
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The 4-6-2 locomotive became almost globally known as a Pacific type. The introduction of the 4-6-2 design in 1901 has been described as a milestone in locomotive progress. Nevertheless, new Pacific designs continued to be built until the mid-1950s, the type is well-suited to high speed running. The world speed record for steam traction of 126 miles per hour has been held by a British Pacific locomotive, the two earliest 4-6-2 locomotives, both created in the United States of America, were experimental designs which were not perpetuated. In 1889, the Chicago, Milwaukee and St. Paul Railway rebuilt a conventional 4-6-0 with trailing wheels as a means of reducing its axle load, in 1896, six Q class 4-6-2 tank locomotives were introduced on the Western Australian Government Railways. Even before Baldwin had completed the order from New Zealand, their engineers realised the advantages of the new type, the design was soon widely adopted by designers throughout the world. There are different opinions concerning the origin of the name Pacific, the design was a natural enlargement of the existing Baldwin 4-4-2 Atlantic type, but the type name may also be in recognition of the fact that a New Zealand designer had first proposed it. Usually, however, new arrangements were named for, or named by. In the case of the Pacific, that was the Missouri Pacific Railroad in 1902, the Pacific type was used on mainline railways around the world. During the first half of the 20th century, the Pacific rapidly became the predominant passenger steam power in North America, between 1902 and 1930, about 6,800 locomotives of the type were built by North American manufacturers for service in the United States and Canada. With exported locomotives included, about 7,300 were built in total, about 45% of these were built by the American Locomotive Company which became the main builder of the type, and 28% by Baldwin. Large numbers were used in South America, most of which were supplied by manufacturers in the United Kingdom. Africa was the continent upon which the Pacific was regularly used. The earliest African examples were built in the United Kingdom by Kitson, within a few weeks, these were followed by a German Pacific type that, although already designed in 1905, only entered service in late 1907. The next was a British type, introduced in January 1908, by the outbreak of the First World War, the type was being widely used on the railways of Continental Europe. The Pacific type was introduced into Asia in 1907, the year that it was first used in Europe. By the 1920s, Pacifics were being used by many throughout the Asian continent. In 1923, the Pacific gave its name to Arthur Honeggers orchestral work, Pacific 231, during the first two decades of the 20th century, the Pacific wheel arrangement enjoyed limited popularity on tank locomotives
4.
Track gauge
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In rail transport, track gauge is the spacing of the rails on a railway track and is measured between the inner faces of the load-bearing rails. All vehicles on a network must have running gear that is compatible with the track gauge, as the dominant parameter determining interoperability, it is still frequently used as a descriptor of a route or network. There is a distinction between the gauge and actual gauge at some locality, due to divergence of track components from the nominal. Railway engineers use a device, like a caliper, to measure the actual gauge, the nominal track gauge is the distance between the inner faces of the rails. In current practice, it is specified at a distance below the rail head as the inner faces of the rail head are not necessarily vertical. In some cases in the earliest days of railways, the company saw itself as an infrastructure provider only. Colloquially the wagons might be referred to as four-foot gauge wagons, say and this nominal value does not equate to the flange spacing, as some freedom is allowed for. An infrastructure manager might specify new or replacement track components at a variation from the nominal gauge for pragmatic reasons. Track is defined in old Imperial units or in universally accepted metric units or SI units, Imperial units were established in United Kingdom by The Weights and Measures Act of 1824. In addition, there are constraints, such as the load-carrying capacity of axles. Narrow gauge railways usually cost less to build because they are lighter in construction, using smaller cars and locomotives, as well as smaller bridges, smaller tunnels. Narrow gauge is often used in mountainous terrain, where the savings in civil engineering work can be substantial. Broader gauge railways are generally expensive to build and require wider curves. There is no single perfect gauge, because different environments and economic considerations come into play, a narrow gauge is superior if ones main considerations are economy and tight curvature. For direct, unimpeded routes with high traffic, a broad gauge may be preferable, the Standard, Russian, and 46 gauges are designed to strike a reasonable balance between these factors. In addition to the general trade-off, another important factor is standardization, once a standard has been chosen, and equipment, infrastructure, and training calibrated to that standard, conversion becomes difficult and expensive. This also makes it easier to adopt an existing standard than to invent a new one and this is true of many technologies, including railroad gauges. The reduced cost, greater efficiency, and greater economic opportunity offered by the use of a common standard explains why a number of gauges predominate worldwide
5.
3 ft 6 in gauge railways
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Railways with a track gauge of 3 ft 6 in/1,067 mm were first constructed as horse-drawn wagonways. From the mid-nineteenth century, the 3 ft 6 in gauge became widespread in the British Empire, there are approximately 112,000 kilometres of 1,067 mm gauge track in the world. 1795 One of the first railways to use 3 ft 6 in gauge was the Little Eaton Gangway in England, other 3 ft 6 in gauge wagonways in England and Wales were also built in the early nineteenth century. 1862 In 1862 the Norwegian engineer Carl Abraham Pihl constructed the first 3 ft 6 in gauge railway in Norway,1865 In 1865 the Queensland Railways were constructed. Its 3 ft 6 in gauge was promoted by the Irish engineer Abraham Fitzgibbon,1868 In 1868 Charles Fox asks civil engineer Edmund Wragge to survey a 3 ft 6 in railway in Costa Rica. 1871 In 1871 the Canadian Toronto, Grey and Bruce Railway,1872 In January 1872 Robert Fairlie advocated the use of 3 ft 6 in gauge in his book Railways Or No Railways, Narrow Gauge, Economy with Efficiency v. Broad Gauge, Costliness with Extravagance. 1872 also saw the opening of the first 3 ft 6 in gauge railway in Japan,1873 On 1 January 1873, the first 3 ft 6 in gauge railway was opened in New Zealand, constructed by the British firm John Brogden and Sons. Earlier built 4 ft 8 1⁄2 in and broad gauge railways were converted to the narrower gauge. Also in 1873 the Cape Colony adopted the 3 ft 6 in gauge, after conducting several studies in southern Europe, the Molteno Government selected the gauge as being the most economically suited for traversing steep mountain ranges. Beginning in 1873, under supervision of Railway engineer of the Colony William Brounger, the Cape Government Railways rapidly expanded and the gauge became the standard for southern Africa. 1876 Natal also converted its short 10 kilometres long Durban network from 4 ft 8 1⁄2 in broad gauge prior to commencing with construction of a network across the colony in 1876. Other new railways in Southern Africa, notably Mozambique, Bechuanaland, after 1876 In the late nineteenth and early twentieth century numerous 3 ft 6 in gauge tram systems were built in the United Kingdom and the Netherlands. In Sweden, the gauge was nicknamed Blekinge gauge, as most of the railways in the province of Blekinge had this gauge. An alternate name for this gauge, Cape gauge, is named after the Cape Colony in what is now South Africa, the term Cape Gauge is used in other languages, such as the Dutch kaapspoor, German Kapspur, Norwegian kappspor and French voie cape. After metrication in the 1960s, the gauge was referred to in official South African Railways publications as 1065 mm instead of 1067 mm, the gauge is sometimes referred to as CAP gauge, after C. A. The gauge name Colonial Gauge was used in New Zealand, in Australia the imperial term 3 foot 6 inch is used. In some Australian publications the term medium gauge is also used, in Japan 1,067 mm gauge is referred to as kyōki, which directly translates as narrow gauge. It is defined in metric units, Cape Government Railways Heritage railway List of track gauges Norwegian gauge controversy South African Trains – A Pictorial Encyclopaedia Why Did Japan Choose the 36 Narrow Gauge
6.
Leading wheel
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The leading wheel or leading axle or pilot wheel of a steam locomotive is an unpowered wheel or axle located in front of the driving wheels. The axle or axles of the wheels are normally located on a leading truck. Leading wheels are used to help the locomotive negotiate curves and to support the front portion of the boiler, importantly, the leading bogie does not have simple rotational motion about a vertical pivot, as might first be thought. It must also be free to slip sideways to a small extent, the sliding bogie of this type was patented by William Adams in 1865. The first use of leading wheels is commonly attributed to John B, Jervis who employed them in his 1832 design for a locomotive with four leading wheels and two driving wheels. In the Whyte system of describing locomotive wheel arrangements, his locomotive would be classified as a 4-2-0, in the UIC classification system, which counts axles rather than wheels and uses letters to denote powered axles, the Jervis would be classified 2A. Locomotives without leading trucks are generally regarded as unsuitable for high speed use, the British Railway Inspectorate condemned the practice in 1895, following an accident involving two 0-4-4s at Doublebois, Cornwall, on the Great Western Railway. A single leading axle increases stability somewhat, while a leading truck is almost essential for high-speed operation. The highest number of leading wheels on a locomotive is six as seen on the 6-2-0 Crampton type. Six-wheel leading trucks were not very popular, the Cramptons were built in the 1840s, but it was not until 1939 that the PRR used one on the S1. AAR wheel arrangement Adams axle Trailing wheel UIC classification Whyte notation
7.
Trailing wheel
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On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle located behind the driving wheels. The axle of the wheels is usually located in a trailing truck. On some large locomotives, an engine was mounted on the trailing truck to provide extra tractive effort when starting a heavy train. Trailing wheels were used in early locomotives but fell out of favor for a time during the latter 19th century. As demand for more powerful locomotives increased, trailing wheels began to be used to support the crew cab, trailing wheels first appeared on American locomotives between 1890 and 1895, but their axle worked in rigid pedestals. It enabled boilers to be lowered, since the top of the frames was dropped down behind the driving wheels. The firebox could also be longer and wider, increasing the surface area and steam generation capacity of the boiler. One-piece cast-steel trailer trucks were developed about 1915, to provide the strength for a booster engine to be fitted to the trailing axle. Finally, about 1921 the Delta trailing truck was developed with a centering device at the rear ends of the truck frame. Delta trucks were soon enlarged to carry four trailing wheels, in the Whyte notation, trailing wheels are designated by the last numbers in the series. For example, the 2-8-2 Mikado type locomotive had two leading wheels, eight driving wheels, and two trailing wheels, some locomotives such as the 4-4-0 American type had no trailing wheels and were designated with a zero in the final place. In the UIC classification system, the number of rather than the number of wheels is counted. AAR wheel arrangement Steam locomotive nomenclature UIC classification Whyte notation
8.
Wheelbase
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In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels. For road vehicles with more than two axles, the wheelbase is defined as the distance between the axle and the centerpoint of the driving axle group. In the case of a truck, the wheelbase would be the distance between the steering axle and a point midway between the two rear axles. The wheelbase of a vehicle equals the distance between its front and rear wheels, at equilibrium, the total torque of the forces acting on a vehicle is zero. So, for example, when a truck is loaded, its center of gravity shifts rearward, the amount the vehicle sinks will depend on counter acting forces like the size of the tires, tire pressure, and the stiffness of the suspension. If the vehicle is accelerating or decelerating, extra torque is placed on the rear or front tire respectively, so, as is common experience, when the vehicle accelerates, the rear usually sinks and the front rises depending on the suspension. Likewise, when braking the front noses down and the rear rises, because of the effect the wheelbase has on the weight distribution of the vehicle, wheelbase dimensions are crucial to the balance and steering. For example, a car with a greater weight load on the rear tends to understeer due to the lack of the load on the front tires. This is why it is crucial, when towing a single-axle caravan, likewise, a car may oversteer or even spin out if there is too much force on the front tires and not enough on the rear tires. Also, when turning there is lateral torque placed upon the tires which imparts a turning force that depends upon the length of the distances from the CM. Wheelbases provide the basis for one of the most common vehicle size class systems, some luxury vehicles are offered with long-wheelbase variants to increase the spaciousness and therefore the luxury of the vehicle. Prime Minister of the United Kingdom Tony Blair was given a version of the Rover 75 for official use. In contrast, coupé varieties of vehicles such as the Honda Accord are usually built on shorter wheelbases than the sedans they are derived from. The wheelbase on many commercially available bicycles and motorcycles is so short, relative to the height of their centers of mass, in skateboarding the word wheelbase is used for the distance between the two inner pairs of mounting holes on the deck. This is different from the distance between the centers of the two wheel pairs. A reason for this use is that decks are sold with prefabricated holes. It is therefore easier to use the holes for measuring and describing this characteristic of the deck. A common misconception is that the choice of wheelbase is influenced by the height of the skateboarder, however, the length of the deck would then be a better candidate, because the wheelbase affects characteristics useful in different speeds or terrains regardless of the height of the skateboarder
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