1.
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
2.
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
3.
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
4.
Belpaire firebox
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The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium in 1864, today it generally refers to the shape of the outer shell of the firebox which is approximately flat at the top and square in cross-section. The flat firebox top would make supporting it against pressure more difficult compared to a round-top, however the use of a similarly shaped square outer boiler shell allows simpler perpendicular stays to be used between the shells. The Belpaire outer firebox is, nevertheless, more complicated and expensive to manufacture than a round-top version, stays are used to support the surfaces against the high pressure between the outside wall and the interior firebox wall, and partially to conduct heat into the boiler interior. In some boiler designs, the top of the boiler is cylindrical above the firebox, matching the contour of the rest of the boiler and those features are difficult to build and weaken the boilers structure. This arrangement gives the firebox end of the boiler a squarer shape, many locomotives with a Belpaire firebox dispense with a steam dome because steam can be collected at the top corners of the firebox. As boilers were made larger, approaching the limit of the British loading gauge, in the USA, the Belpaire firebox was introduced in about 1882 or 83 by R. P. C. Sanderson, who at the time was working for the Shenandoah Valley Railway, Sanderson was an Englishman who had attained his engineering degree from Cassel in Germany in 1875. Having obtained knowledge of a form of locomotive boiler, Sanderson wrote to an old acquaintance from his college days who was working at the Henschel locomotive factory at Cassel. He sent Sanderson a tracing of Henschels latest Belpaire boiler and this was the beginning of the use of this type of locomotive boilers in the United States. The Pennsylvania Railroad used Belpaire fireboxes on nearly all of its steam locomotives
5.
Safety valve
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A safety valve is a valve that acts as a fail-safe in a thermal-hydraulics plant. Pilot-operated relief valves are a type of pressure safety valve. Safety valves were first developed for use on steam boilers during the Industrial Revolution, early boilers operating without them were prone to explosion. Vacuum safety valves are used to prevent a tank from collapsing while it is being emptied, when sizing a vacuum safety valve, the calculation method is not defined in any norm, particularly in the hot CIP / cold water scenario, but some manufacturers have developed sizing simulations. The earliest and simplest safety valve was used on a 1679 steam digester and utilized a weight to retain the steam pressure, however, on the Stockton and Darlington Railway, the safety valve tended to go off when the engine hit a bump in the track. A valve less sensitive to sudden accelerations used a spring to contain the steam pressure and this dangerous practice was sometimes used to marginally increase the performance of a steam engine. In 1856, John Ramsbottom invented a tamper-proof spring safety valve that became universal on railways, Safety valves also evolved to protect equipment such as pressure vessels and heat exchangers. The term safety valve should be limited to compressible fluid applications, the two general types of protection encountered in industry are thermal protection and flow protection. Flow protection is characterized by safety valves that are larger than those mounted for thermal protection. They are generally sized for use in situations where significant quantities of gas or high volumes of liquid must be discharged in order to protect the integrity of the vessel or pipeline. This protection can alternatively be achieved by installing a high integrity pressure protection system, Relief valve, an automatic system that is actuated by the static pressure in a liquid-filled vessel. It specifically opens proportionally with increasing pressure, Safety valve, an automatic system that relieves the static pressure on a gas. It usually opens completely, accompanied by a popping sound, Safety relief valve, an automatic system that relieves by static pressure on both gas and liquid. Pilot-operated safety relief valve, a system that relieves on remote command from a pilot. Low pressure safety valve, a system that relieves static pressure on a gas. Used when the difference between the pressure and the ambient atmospheric pressure is small. Vacuum pressure safety valve, a system that relieves static pressure on a gas. Used when the difference between the vessel pressure and the ambient pressure is small, negative and near to atmospheric pressure
6.
Valve gear
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It can also serve as a reversing gear. It is sometimes referred to as the motion, in the simple case, this can be a relatively simple task as in the internal combustion engine in which the valves always open and close at the same points. A further benefit may be obtained by admitting the steam to the cylinder slightly before front or back dead centre and this advanced admission assists in cushioning the inertia of the motion at high speed. Instead, a system of eccentrics, cranks and levers is used to control a D slide valve or piston valve from the motion. Generally, two simple harmonic motions with different fixed phase angles are added in varying proportions to provide a motion that is variable in phase. A variety of mechanisms have been devised over the years. Both slide and piston valves have the limitation that intake and exhaust events are fixed in relation to each other, lap is provided on steam edges of the valve, so that although the valve stroke reduces as cutoff is advanced, the valve is always fully opened to exhaust. However, as cutoff is shortened, the exhaust events also advance, the exhaust release point occurs earlier in the power stroke and compression earlier in the exhaust stroke. Early release wastes some energy in the steam, and early closure also wastes energy in compressing an otherwise unnecessarily large quantity of steam and these inefficiencies drove the widespread experimentation in poppet valve gears for locomotives. Intake and exhaust poppet valves could be moved and controlled independently of each other, a very late British design, the SR Leader class, used sleeve valves adapted from internal combustion engines, but this class was not a success. In stationary steam engines, traction engines and marine engine practice, in stationary engines trip valves were also extensively used. Valve gear was a field of invention, with probably several hundred variations devised over the years. However, only a number of these saw any widespread use. They can be divided into those that drove the standard reciprocating valves, those used with poppet valves, slip-eccentric - This gear is now confined to model steam engines, and low power hobby applications such as steam launch engines, ranging to a few horsepower. The eccentric is loose on the crankshaft but there are stops to limit its rotation relative to the crankshaft, the engine is pushed forwards to put the eccentric in the forward gear position and backwards to put it in the backward gear position. There is no control of cutoff. These included the Teutonic, Greater Britain and John Hick classes, gab or hook gear - used on earliest locomotives. Allowed reversing but no control of cutoff, one component of the motion comes from a crank or eccentric
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