A railcar, in British English and Australian English, is a self-propelled railway vehicle designed to transport passengers. The term "railcar" is used in reference to a train consisting of a single coach, with a driver's cab at one or both ends; some railway companies, such as the Great Western, termed such vehicles "railmotors". Self-propelled passenger vehicles capable of hauling a train are, in technical rail usage, more called "rail motor coaches" or "motor cars"; the term is sometimes used as an alternative name for the small types of multiple unit which consist of more than one coach. That is the general usage nowadays in Ireland when referring to any diesel multiple unit, or in some cases electric multiple unit. In North America the term "railcar" has a much broader sense and can be used to refer to any item of hauled rolling-stock, whether passenger coaches or goods wagons. In its simplest form, a "railcar" may be little more than a motorized railway handcar or draisine, otherwise known as a speeder.
Railcars are economic to run for light passenger loads because of their small size, in many countries are used to run passenger services on minor railway lines, such as rural railway lines where passenger traffic is sparse, where the use of a longer train would not be cost effective. A famous example of this in the United States was the Galloping Goose railcars of the Rio Grande Southern Railroad, whose introduction allowed the discontinuance of steam passenger service on the line and prolonged its life considerably. Railcars have been employed on premier services. In New Zealand, although railcars were used on regional services, the Blue Streak and Silver Fern railcars were used on the North Island Main Trunk between Wellington and Auckland and offered a higher standard of service than previous carriage trains. In Australia, the Savannahlander operates a tourist service from the coastal town of Cairns to Forsayth, Traveltrain operates the Gulflander between Normanton and Croydon in the Gulf Country of northern Queensland.
William Bridges Adams built steam railcars at London in the 1840s. Many British railway companies tried steam railcars but they were not successful and were replaced by push-pull trains. Sentinel Waggon Works was one British builder of steam railcars. In Belgium, M. A. Cabany of Mechelen designed steam railcars, his first was exhibited at a Paris exhibition. This may have been the Exposition Universelle; the steam boiler was supplied by the Boussu Works and there was accommodation for First and Third-class passengers and their luggage. There was a locker for dogs underneath. Fifteen were built and they worked in the Hainaut and Antwerp districts. In 1904 the Automotor Journal reported that one railway after another had been realising that motor coaches could be used to handle light traffic on their less important lines; the North-Eastern railways had been experimenting “for some time” in this direction, Wolseley provided them with a flat-four engine capable of up to 100 bhp for this purpose. The engine drove a main dynamo to power two electric drive motors, a smaller dynamo to charge accumulators to power the interior lighting and allow electric starting of the engine.
The controls for the dynamo allowed the coach to be driven from either end. For further details see 1903 Petrol Electric Autocar. Another early railcar in the UK was designed by James Sidney Drewry and made by the Drewry Car Co. in 1906. In 1908 the manufacture was contracted out to the Birmingham Small Arms Company. While early railcars were propelled by steam and diesel engines, modern railcars are propelled by a diesel engine mounted underneath the floor of the coach. Diesel railcars may have hydraulic or diesel-electric transmission. Electric railcars on mainline electric systems are rare, since electrification implies heavy usage where single cars or short trains would not be economic. Exceptions to this rule were found for example in Sweden or Switzerland; some vehicles on tram and interurban systems, like the Red Car of the Pacific Electric Railway, can be seen as railcars. Experiments with battery-electric railcars were conducted from around 1890 in Belgium, France and Italy. In the USA, railcars of the Edison-Beach type, with nickel-iron batteries were used from 1911.
In New Zealand, a battery-electric Edison railcar operated from 1926 to 1934. The Drumm nickel-zinc battery was used on four 2-car sets between 1932 and 1946 on the Harcourt Street Line in Ireland and British Railways used lead-acid batteries in a railcar in 1958. Between 1955 and 1995 DB railways operated 232 DB Class ETA 150 railcars utilising lead-acid batteries; as with any other battery electric vehicle, the drawback is the limited range, and/or expense of the battery. An example of a new application for zero emission vehicles for rail environments such as subways is the Cater MetroTrolley which carries ultrasonic flaw detection instrumentation. A new breed of modern lightweight aerodynamically designed diesel or electric regional railcars that can operate as single vehicles or in trains are becoming popular in Europe and Japan, replacing the first-generation railbuses and second-generation DMU railcars running on lesser-used main-line railways and in some cases in exclusive lanes in urban areas.
Like many high-end DMUs, these
Maybach Motorenbau is a defunct German car manufacturer that today exists as a sub-brand of Mercedes-Benz. The company was founded in 1909 by Wilhelm Maybach and his son as a subsidiary of Luftschiffbau Zeppelin GmbH, it was known as Luftfahrzeug-Motorenbau GmbH until 1999. In 1960, Maybach was acquired by Daimler-Benz; the name returned as a standalone ultra-luxury car brand in the late 20th century and early 21st century, sharing significant components with Mercedes-Benz cars. After slow sales, Maybach ceased to be a standalone brand by 2013, it became a sub-brand of Mercedes-Benz, owned by Daimler AG; as of 2018, Daimler produces an ultra-luxury edition of the Mercedes-Benz S-Class under the Mercedes-Maybach name. Wilhelm Maybach was technical director of the Daimler-Motoren-Gesellschaft until he left in 1907. On 23 March 1909, he founded the new company, Luftfahrzeug-Motorenbau GmbH, with his son Karl Maybach as director. In 1912, they renamed it to Maybach-Motorenbau GmbH; the company developed and manufactured diesel and petrol engines for Zeppelins, rail cars.
Its Maybach Mb. IVa was used in aircraft and airships of World War I; the company first built an experimental car in 1919, introduced as a production model two years at the Berlin Motor Show. Between 1921 and 1940, the company produced a variety of opulent vehicles; the company continued to build heavy-duty diesel engines for marine and rail purposes. Maybach had Maybach Gears Ltd, that specialised in gearboxes. In 1938, in conjunction with Dr Henry Merritt, they produced a gearbox and steering system - the'Merritt-Maybach' - for the abortive Nuffield A.16E1 Cruiser tank design. During the Second World War, Maybach produced the engines for most of Nazi Germany's tanks and half-tracks; these included all the production tank engines through Panzer I, II, III, IV and V, the Tiger I and II and other heavy tanks: and engines for half-tracks such as the Sd. Kfz. 251 personnel carrier and prime movers like the Sd. Kfz. 9. The engine plant was one of several industries targeted at Friedrichshafen. After WW II, the factory performed some repair work, but automotive production was never restarted, some 20 years the company was renamed MTU Friedrichshafen.
Daimler-Benz purchased the company in 1960. Post-1960, the company was used to make special editions of Mercedes cars in the W108 and W116 model range, which were hand built; these cars however carried the Mercedes serial numbers. Rolls-Royce Power Systems AG, based in Friedrichshafen, used to manufacture the commercial Maybach diesel engines under the MTU brand through its subsidiary MTU Friedrichshafen GmbH. Daimler presented a luxury concept car at the 1997 Tokyo Motor Show. A production model based on it was introduced in two sizes – the Maybach 57 and the Maybach 62, reflecting the lengths of the automobiles in decimetres. In 2005 the 57S was added, powered by a 6.0 L V12 bi-turbo engine producing 450 kW and 1,000 N⋅m of torque, featuring various cosmetic touches. To promote the new Maybach line, Mercedes-Benz engaged figures such as Maybach heir Ulrich Schmid-Maybach and golfer Nick Faldo to serve as brand ambassadors. Daimler-Chrysler predicted annual sales of 2,000 worldwide with 50 per cent coming from the United States.
In 2007, Mercedes bought back 29 US dealers, reducing the total from 71 to 42. In 2010, only 157 Maybachs were sold worldwide, compared to 2,711 priced Rolls-Royces. Just 3,000 have been sold worldwide since the brand was revived in 2002. Daimler announced in November 2011 that Maybach would cease to be a brand by 2013 and manufactured the last Maybach vehicle in December 2012; this was because of poor sales. With poor sales expectations and the heavy impact of the 2007-08 financial crisis, Daimler AG undertook a complete review of the Maybach division, approaching Aston Martin to engineer and style the next generation of Maybach models along with the next generation of Lagondas. According to Automotive News, only 44 Maybachs had been sold in the U. S. through October 2011. An article in Fortune noted that Mercedes had missed out on the chance to purchase Rolls-Royce and Bentley when they were up for sale in the 1990s: "Mercedes backpedaled and decided it needed to be in the ultra-luxury business too, but it went after it in a remarkably clumsy way."
It further stated that the first Maybach models had poor driving dynamics compared to its contemporaries from Rolls-Royce and Bentley: "Mercedes took an aging S-class chassis and plopped an absurdly elongated body on it... rather than develop a new car from the wheels up, as BMW did with Rolls-Royce, or cleverly use the underpinnings of an existing model like the Volkswagen Phaeton for a new Bentley." Furthermore, Maybachs were never advertised as owner-driven vehicles, as the company believed that the luxury amenities would be sufficient to drive sales, they insisted that auto journalists ride in the backseat. Another suggestion for Maybach's struggles was that parent Daimler had failed to differentiate it from its Mercedes-Benz brand. While all three ultra-luxury marques share platforms and engines with other luxury brands from their parent auto company, Maybachs are built alongside the Mercedes-Benz S-Class flagship sedan, whereas Rolls-Royce and Bentley are assembled in England, thus are regarded as being more "exclusive".
Furthermore, the Maybach's pedigree was unknown outside of German
In aeronautics, a propeller called an airscrew, converts rotary motion from an engine or other power source into a swirling slipstream which pushes the propeller forwards or backwards. It comprises a rotating power-driven hub, to which are attached several radial airfoil-section blades such that the whole assembly rotates about a longitudinal axis; the blade pitch may be fixed, manually variable to a few set positions, or of the automatically-variable "constant-speed" type. The propeller attaches to the power source's driveshaft either directly or through reduction gearing. Propellers can be made from metal or composite materials. Propellers are only suitable for use at subsonic airspeeds below about 480 mph, as above this speed the blade tip speed approaches the speed of sound and local supersonic flow causes high drag and propeller structural problems; the earliest references for vertical flight came from China. Since around 400 BC, Chinese children have played with bamboo flying toys; this bamboo-copter is spun by rolling a stick attached to a rotor between ones hands.
The spinning creates lift, the toy flies when released. The 4th-century AD Daoist book Baopuzi by Ge Hong describes some of the ideas inherent to rotary wing aircraft. Designs similar to the Chinese helicopter toy appeared in other works, it was not until the early 1480s, when Leonardo da Vinci created a design for a machine that could be described as an "aerial screw", that any recorded advancement was made towards vertical flight. His notes suggested that he built small flying models, but there were no indications for any provision to stop the rotor from making the craft rotate; as scientific knowledge increased and became more accepted, man continued to pursue the idea of vertical flight. Many of these models and machines would more resemble the ancient bamboo flying top with spinning wings, rather than Leonardo's screw. In July 1754, Russian Mikhail Lomonosov had developed a small coaxial modeled after the Chinese top but powered by a wound-up spring device and demonstrated it to the Russian Academy of Sciences.
It was powered by a spring, was suggested as a method to lift meteorological instruments. In 1783, Christian de Launoy, his mechanic, used a coaxial version of the Chinese top in a model consisting of contrarotating turkey flight feathers as rotor blades, in 1784, demonstrated it to the French Academy of Sciences. A dirigible airship was described by Jean Baptiste Marie Meusnier presented in 1783; the drawings depict a 260-foot-long streamlined envelope with internal ballonets that could be used for regulating lift. The airship was designed to be driven by three propellers. In 1784 Jean-Pierre Blanchard fitted a hand-powered propeller to a balloon, the first recorded means of propulsion carried aloft. Sir George Cayley, influenced by a childhood fascination with the Chinese flying top, developed a model of feathers, similar to that of Launoy and Bienvenu, but powered by rubber bands. By the end of the century, he had progressed to using sheets of tin for rotor blades and springs for power, his writings on his experiments and models would become influential on future aviation pioneers.
William Bland sent designs for his "Atmotic Airship" to the Great Exhibition held in London in 1851, where a model was displayed. This was an elongated balloon with a steam engine driving twin propellers suspended underneath. Alphonse Pénaud developed coaxial rotor model helicopter toys in 1870 powered by rubber bands. In 1872 Dupuy de Lome launched a large navigable balloon, driven by a large propeller turned by eight men. Hiram Maxim built a craft that weighed 3.5 tons, with a 110-foot wingspan, powered by two 360-horsepower steam engines driving two propellers. In 1894, his machine was tested with overhead rails to prevent it from rising; the test showed. One of Pénaud's toys, given as a gift by their father, inspired the Wright brothers to pursue the dream of flight; the twisted airfoil shape of an aircraft propeller was pioneered by the Wright Brothers. While some earlier engineers had attempted to model air propellers on marine propellers, the Wright Brothers realized that a propeller is the same as a wing, were able to use data from their earlier wind tunnel experiments on wings, introducing a twist along the length of the blades.
This was necessary to maintain a more uniform angle of attack of the blade along its length. Their original propeller blades had an efficiency of about 82%, compared to 90% for a modern small general aviation propeller, the 3-blade McCauley used on a Bonanza aircraft. Roper quotes 90% for a propeller for a human-powered aircraft. Mahogany was the wood preferred for propellers through World War I, but wartime shortages encouraged use of walnut, oak and ash. Alberto Santos Dumont was another early pioneer, having designed propellers before the Wright Brothers for his airships, he applied the knowledge he gained from experiences with airships to make a propeller with a steel shaft and aluminium blades for his 14 bis biplane in 1906. Some of his designs used a bent aluminium sheet for blades, they were undercambered, this plus the absence of lengthwise twist made them less efficient than the Wright propellers. So, this was the first use of aluminium in the construction of an airscrew. A rotating airfoil behind the aircraft, which pushes it, was called a propeller, while one which pulled from the front was a tractor.
The term'pusher' became adopted for the rear-mounted device in contrast to the tractor configurat
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles and electronics; the radiator is always a source of heat to its environment, although this may be for either the purpose of heating this environment, or for cooling the fluid or coolant supplied to it, as for engine cooling. Despite the name, most radiators transfer the bulk of their heat via convection instead of thermal radiation; the Roman hypocaust is an early example of a type of radiator for building space heating. Franz San Galli, a Prussian-born Russian businessman living in St. Petersburg, is credited with inventing the heating radiator around 1855, having received a radiator patent in 1857, but American Joseph Nason developed a primitive radiator in 1841 and received a number of U. S. patents for hot water and steam heating. Heat transfer from a radiator occurs by all the usual mechanisms: thermal radiation, convection into flowing air or liquid, conduction into the air or liquid.
A radiator may transfer heat by phase change, for example, drying a pair of socks. In practice, the term "radiator" refers to any of a number of devices in which a liquid circulates through exposed pipes; the term "convector" refers to a class of devices in which the source of heat is not directly exposed. To increase the surface area available for heat exchange with the surroundings, a radiator will have multiple fins, in contact with the tube carrying liquid pumped through the radiator. Air in contact with the fins carries off heat. If air flow is obstructed by dirt or damage to the fins, that portion of the radiator is ineffective at heat transfer. Radiators are used to heat buildings. In a central heating system, hot water or sometimes steam is generated in a central boiler and circulated by pumps through radiators within the building, where this heat is transferred to the surroundings. Radiators are used for cooling internal combustion engines in automobiles but in piston-engined aircraft, railway locomotives, stationary generating plants and other places where such engines are used.
To cool down the engine, a coolant is passed through the engine block, where it absorbs heat from the engine. The hot coolant is fed into the inlet tank of the radiator, from which it is distributed across the radiator core through tubes to another tank on the opposite end of the radiator; as the coolant passes through the radiator tubes on its way to the opposite tank, it transfers much of its heat to the tubes which, in turn, transfer the heat to the fins that are lodged between each row of tubes. The fins release the heat to the ambient air. Fins are used to increase the contact surface of the tubes to the air, thus increasing the exchange efficiency; the cooled coolant is fed back to the engine, the cycle repeats. The radiator does not reduce the temperature of the coolant back to ambient air temperature, but it is still sufficiently cooled to keep the engine from overheating; this coolant is water-based, with the addition of glycols to prevent freezing and other additives to limit corrosion and cavitation.
However, the coolant may be an oil. The first engines used thermosiphons to circulate the coolant. Up to the 1980s, radiator cores were made of copper and brass. Starting in the 1970s, use of aluminium increased taking over the vast majority of vehicular radiator applications; the main inducements for aluminium are reduced cost. Since air has a lower heat capacity and density than liquid coolants, a large volume flow rate must be blown through the radiator core to capture the heat from the coolant. Radiators have one or more fans that blow air through the radiator. To save fan power consumption in vehicles, radiators are behind the grille at the front end of a vehicle. Ram air can give a portion or all of the necessary cooling air flow when the coolant temperature remains below the system's designed maximum temperature, the fan remains disengaged; as electronic devices become smaller, the problem of dispersing waste heat becomes more difficult. Tiny radiators known as heat sinks are used to convey heat from the electronic components into a cooling air stream.
Heatsink do not use water, rather they conduct the heat from the source. Heat is transferred to the air by convection. Radiators are found as components of some spacecraft; these radiators work by radiating heat energy away as light because in the vacuum of space neither convection nor conduction can work to transfer heat away. On the International Space Station, these can be seen as large white panels attached to the main truss, they can be found on both manned and unmanned craft
Aluminium or aluminum is a chemical element with symbol Al and atomic number 13. It is a silvery-white, soft and ductile metal in the boron group. By mass, aluminium makes up about 8% of the Earth's crust; the chief ore of aluminium is bauxite. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals. Aluminium is remarkable for its low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the aerospace industry and important in transportation and building industries, such as building facades and window frames; the oxides and sulfates are the most useful compounds of aluminium. Despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals; because of these salts' abundance, the potential for a biological role for them is of continuing interest, studies continue.
Of aluminium isotopes, only 27Al is stable. This is consistent with aluminium having an odd atomic number, it is the only aluminium isotope that has existed on Earth in its current form since the creation of the planet. Nearly all the element on Earth is present as this isotope, which makes aluminium a mononuclidic element and means that its standard atomic weight equates to that of the isotope; the standard atomic weight of aluminium is low in comparison with many other metals, which has consequences for the element's properties. All other isotopes of aluminium are radioactive; the most stable of these is 26Al and therefore could not have survived since the formation of the planet. However, 26Al is produced from argon in the atmosphere by spallation caused by cosmic ray protons; the ratio of 26Al to 10Be has been used for radiodating of geological processes over 105 to 106 year time scales, in particular transport, sediment storage, burial times, erosion. Most meteorite scientists believe that the energy released by the decay of 26Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago.
The remaining isotopes of aluminium, with mass numbers ranging from 21 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. An aluminium atom has 13 electrons, arranged in an electron configuration of 3s23p1, with three electrons beyond a stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Aluminium can easily surrender its three outermost electrons in many chemical reactions; the electronegativity of aluminium is 1.61. A free aluminium atom has a radius of 143 pm. With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure, aluminium atoms form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; this crystal system is shared by some other metals, such as copper. Aluminium metal, when in quantity, is shiny and resembles silver because it preferentially absorbs far ultraviolet radiation while reflecting all visible light so it does not impart any color to reflected light, unlike the reflectance spectra of copper and gold.
Another important characteristic of aluminium is its low density, 2.70 g/cm3. Aluminium is a soft, lightweight and malleable with appearance ranging from silvery to dull gray, depending on the surface roughness, it is nonmagnetic and does not ignite. A fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation; the yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has stiffness of steel, it is machined, cast and extruded. Aluminium atoms are arranged in a face-centered cubic structure. Aluminium has a stacking-fault energy of 200 mJ/m2. Aluminium is a good thermal and electrical conductor, having 59% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss.
Aluminium is the most common material for the fabrication of superconducting qubits. Aluminium's corrosion resistance can be excellent due to a thin surface layer of aluminium oxide that forms when the bare metal is exposed to air preventing further oxidation, in a process termed passivation; the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts in the presence of dissimilar metals. In acidic solutions, aluminium reacts with water to form hydrogen, in alkaline ones to form aluminates—protective passivation under these conditions is negligible; because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium. However, because
A wagon is a heavy four-wheeled vehicle pulled by draught animals or on occasion by humans, used for transporting goods, agricultural materials and sometimes people. Wagons are distinguished from carts and from lighter four-wheeled vehicles for carrying people, such as carriages. Wagons are pulled by animals such as horses, mules or oxen, they may be pulled by one animal or by several in pairs or teams. However, there are examples such as mining corfs. A wagon was called a wain and one who builds or repairs wagons is a wainwright. More a wain is a type of horse- or oxen-drawn, load-carrying vehicle, used for agricultural purposes rather than transporting people. A wagon or cart four-wheeled. However, a two-wheeled "haywain" would be a hay cart, as opposed to a carriage. Wain is an archaic term for a chariot. Wain can be a verb, to carry or deliver, has other meanings. A person who drives wagons is called a "wagoner", a "teamster", a "bullocky", a "muleskinner", or a "driver"; the exact name and terminology used is dependent on the design or shape of the wagon.
If low and sideless may be called a dray, trolley or float. When traveling over long distances and periods, wagons may be covered with cloth to protect their contents from the elements. If it has a permanent top enclosing it, it may be called a "van". Turning radius was a longstanding problem with wagons, dictated by the distance between the front wheels and the bed of the wagon—namely, the point where the rotating wheels collide with the side of the wagon when turning. Many earlier designs required a large turning radius; as this is a problem that carts do not face, this factor, combined with their lighter weight, meant that carts were long preferred over wagons for many uses. The general solutions to this problem involved several modifications to the front-axle assembly; the front axle assembly of a wagon consists of an axle, a pair of wheels and a round plate with a pin in its centre that sits halfway between the wheels. A round plate with a hole in its centre is located on the underside of the wagon.
The plate on the wagon, in turn, sits on the plate on the axle between the wheels. This arrangement allows wheels to turn horizontally; the pin and hole arrangement could be reversed. The horse harness is attached to this assembly. To enable the wagon to turn in as little space as possible, the front pair of wheels are made smaller than the rear pair to allow them to turn close under the vehicle sides, to allow them to turn still further, the wagon body may be waisted; this technique led to further designs well-adapted to narrow areas. Wagons have served numerous purposes, with numerous corresponding designs; as with motorized vehicles, some are designed to serve as many functions as possible, while others are specialized. This section will discuss a broad overview of the general classes of wagons. Farm wagons are built for general multi-purpose usage in an rural setting; these include gathering hay and wood, delivering them to the farmstead or market. A common form found throughout Europe is the leiterwagen, a large wagon where the sides consist of ladders strapped in place to hold in hay or grain, though these could be removed to serve other needs.
A common type of farm wagon particular to North America is the buckboard. Freight wagons are wagons used for the overland hauling of bulk commodities. In the United States and Canada, the Conestoga wagon was a predominant form of wagon used for hauling freight in the late 18th and 19th centuries used for hauling goods on the Great Wagon Road in the Appalachian Valley and across the Appalachian Mountains. Larger freight wagons existed. For instance, the "twenty-mule team" wagons, used for hauling borax from Death Valley, could haul 36 short tons per pair; the wagons' bodies were 6 feet deep. A delivery wagon is a wagon used to deliver merchandise such as milk, bread, or produce to houses or markets, as well as to commercial customers in urban settings; the concept of express wagons and of paneled delivery vans developed in the 19th century. By the end of the 19th century, delivery wagons were finely painted and varnished, so as to serve as advertisement for the particular business through the quality of the wagon.
Special forms of delivery wagon include a milk wagon. Some wagons are intended to serve as mobile workshops; these include a traditional wagon of the 19th-century British Romani people. The steam wagon, a self-powered development of the horse-drawn wagon, was a late innovation, entering service only in the late nineteenth century. In the city center of Schwäbisch Gmünd, since 1992 the city's plants are irrigated using a horse-drawn wagon with a water tank. In migration and military settings, wagons were found in large groups called wagon trains. In warfare, large groups of supply wagons were used to support traveling armies with food and munitio
SNCF TGV Duplex
The TGV Duplex is a French high-speed train of the TGV family, manufactured by Alstom, operated by the French national railway company SNCF. It is unique among TGV trains; the Duplex inaugurated the third generation of TGV trainsets. It was specially designed to increase capacity on high-speed lines with saturated traffic. With two seating levels and a seating capacity of 508 passengers, the Duplex increases the passenger capacity. While the TGV Duplex started as a small component of the TGV fleet, it has become one of the system's workhorses; the LGV Sud-Est from Paris to Lyon is the busiest high-speed line in France. After its opening in 1981 it reached capacity. Several options were available to increase capacity; the separation between trains was reduced to three minutes on some TGV lines, but the complex signalling systems, high-performance brakes required, limited this option. Another option is to widen the train but is not practicable due to loading gauge restrictions. Running two trainsets coupled together in multiple-unit configuration provides extra capacity, but required long station platforms.
Given length and width restrictions, the remaining option is to adopt a bi-level configuration, with seating on two levels, adding 45% more passenger capacity. TGV Duplex sets are run with a single deck Réseau set or another Duplex set; the Duplex feasibility study was completed in 1987. In 1988, a full-scale mockup was built to gauge customer reactions to the bi-level concept, traditionally associated with commuter and regional rail rather than with high-speed intercity trains. A TGV Sud-Est trailer was tested in revenue service with the inside furnished to simulate the lower floor of a bi-level arrangement, that year another TGV Sud-Est was modified to study the dynamic behavior of a train with a higher center of gravity. Discussions with GEC-Alsthom began soon after, in July 1990 the company won the contract to build the "TGV-2N", as it was known; the contract was finalized in early 1991. The first tests of a bi-level trainset were in November 1994. Soon after their first run, the first rake of eight trailers was tested at 290 km/h on the Sud-Est line.
The trainset was powered by TGV Réseau power cars at the time, as the Duplex power cars were not ready. The first Duplex power car was mated to the bi-level trailers on 21 June 1995; the most important innovation is the efficiency of the Duplex design. Comparing an original TGV Sud-Est and a Duplex trainset shows that the double-decker design has improvements in both power-to-weight ratio and weight-per-seat overhead: In this comparison, "power" refers to installed power, not all of, used when operating. Aluminium bodies: the strict requirement of a 17-tonne axle load limit made it imperative to cut down on weight, wherever possible. Extruded aluminum construction made possible a 20% reduction in structure weight. Improved styling and aerodynamics: the nose of the power units and the gap between trailers were improved such that a Duplex train at cruise speed of 300 km/h experiences only 4% more drag than a single-level TGV; the nose, the first significant departure from Cooper's original design, was styled by industrial designer Roger Tallon, as was the rest of the trainset.
Crashworthiness: crush zones and rigid passenger compartments protect safety in the event of a collision. The power units' frame is designed to take a 500 tonnes of force frontal load, features structural fuses to absorb impact energy. Active pantograph: the Faiveley CX used on the Duplex has a pneumatically actuated active control system. Two small gas cylinders in the wiper armature can tune the stiffness of the pantograph's upper stage, to optimize contact at any speed. All wheel disc brakes: earlier TGVs used disc brakes only on unpowered axles. Weight gains on the Duplex power units allowed the installation of disc brakes directly on the wheels of powered axles, instead of using the traditional tread brakes; this does not improve braking performance, but it leaves the wheel tread smooth and reduces rolling noise. Quiet roof fans: the cooling fans in TGV power units produce the most noticeable sound when the train is in a station; the fans, located in the roof of the unit, were redesigned to be quieter.
World's fastest train: in 2007 a short formation TGV Duplex was fitted with distributed traction as used in the future generation AGV setting a new speed record of 574.8 km/h. Known as Réseau Duplex, they take the serial number 600; this version came into existence when the carriages of nineteen TGV-Réseau sets were used to create the TGV POS sets. The Réseau powercars of these sets, with some aerodynamic adjustments, joined new Duplex sets, they were the first series of "inter-recoupled series" TGV to achieve a sustainable basis by SNCF. Instead of ordering brand new POS sets, the railways modified a pre-existing order for 19 Duplex as follows: 19 sets of 8 Duplex-carriages, identical to the original TGV Duplex, to be powered by the 38 surplus TGV Réseau powercars. 38 new tri-current powercars, based on the Duplex-version, making them suitable for use on the Deutsche Bahn's and Swiss Federal Railways' networks. These were joined to the nineteen sets of Réseau carriages, renovated by Christian Lacroix, becoming the series "4400" or TGV POS.
Their livery is identical to that of other Duplex units. Called "duplex", these 19 units, number