All examples of this type are cab forwards. Normally, the leading truck sits under the smokebox and the trailing truck under the firebox. On a cab-forward, the leading truck supports the firebox and the trailing truck and smokebox are at the rear next to the tender. A 4-8-8-2 is effectively a 2-8-8-4 that always runs in reverse.
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The trailing wheels (boxed) on a 4-6-2 locomotive. A cross-sectional view of a rigid trailing truck On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle (wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing truck. On some large locomotives, a booster engine was mounted on the trailing truck to provide extra tractive effort when starting a heavy train and at low speeds on gradients. Trailing wheels were used in some early locomotives but fell out of favor for a time during the latter 19th century.
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FA 9 also differed from the standard rebuilds in that its trailing truck had outside journal boxes instead of the internal type used on the other engines.
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A large increase in firebox area (from on the H-10 to on the A-1), characteristic of his work, necessitated adding another axle to the trailing truck, thus creating the 2-8-4 wheel arrangement. Built in the spring of 1925, the first Berkshire (a demonstrator owned by Lima) was dubbed the A-1. In addition to supporting the very large firebox and grate, the four-wheeled trailing truck carried the ash pan. For this purpose, the truck was redesigned as an articulated extension of the locomotive frame.
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The four- wheel trailing truck became the standard for large locomotives (i.e. 4-8-4, 2-10-4, 4-6-6-4, 2-8-8-4), though the articulated main frame did not. Many railroads, particularly roads like the Santa Fe (which favored oil burning locomotives and, therefore, did not need the oversized ash pan), adopted many of the Super Power features but utilized a conventional full frame and separate trailing truck. The construction of the first 2-8-4 locomotive is documented in David Weitzman's book, Superpower: Making of a steam locomotive.
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The Atchison, Topeka & Santa Fe Railway (ATSF) took delivery of locomotive No. 3829 from the Baldwin Locomotive Works in 1919. It was used by Santa Fe as an experimental locomotive and was rostered as a member of ATSF’s 3800 class of 2-10-2s that was fitted with a four-wheel trailing truck. Nearly one-hundred more 3800 class locomotives were delivered after No. 3829, but all with the 2-10-2 wheel arrangement. Photographs exist that show No. 3829 fitted with at least two different designs of four-wheel trailing truck through the years.
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Similarly to the earlier D57 class (which had some input from Young) the massively proportioned locomotive incorporated a cast steel chassis. The design also sported cast Boxpok coupled wheels for better rotational balance, and a Delta trailing truck.
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The experiment did result in the successor Class 19C being built with rotary cam poppet valve gear. The trailing bissel truck was constructed with three holes to enable the compensating beam to be fitted at three locations, which enabled it to be used to redistribute the engine's weight on the trailing axle. The axle load weights as shown for the Class 19B are with the trailing truck compensating beam pin in the rearmost of the three holes. The axle load weights as shown for the Class 19BR are also with the trailing truck compensating beam pin in the rearmost of the three holes.
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The booster engine was an auxiliary steam engine which provided extra tractive effort for starting. It was a low-speed device, usually mounted on the trailing truck. It was dis- engaged via an idler gear at a low speed, e.g. 30 km/hr.
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It was returned to Baldwin where it was rebuilt into a 2-8-8-0 and a 2-8-2. A two wheel trailing truck was added later, making it into a 2-8-8-2. These two locomotives were operated until 1953.
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Under the Whyte notation for the classification of steam locomotives, 2-12-2 represents the wheel arrangement of two leading wheels on one axle (usually in a leading truck), twelve powered and coupled driving wheels on six axles, and two trailing wheels on one axle (usually in a trailing truck).
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X36 and X37 were built without boosters and were rostered for 'plains working' on the relatively flat line between Gheringhap and Maroona stations. X37 was equipped with a booster in March 1932, however X36 was never fitted with one, even though its trailing truck axle was equipped with the necessary pinion gear wheel.
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While the aim was to reduce the locomotive's total weight for use on some of the more lightly laid branch lines, the actual achieved weight saving was a mere four tons which could hardly have justified the cost of redesigning. The trailing bissel truck was constructed with three holes to enable the compensating beam to be fitted at three locations which enabled it to be used to redistribute the engine's weight on the trailing axle. The axle load weights as listed for the Class 19A are with the trailing truck compensating beam pin in the leading of the three holes. The axle load weights as listed for the Class 19AR are with the trailing truck compensating beam pin in the centre hole.
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An 0-4-6T, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a locomotive with no leading wheels, four driving wheels fixed in a rigid frame, and six trailing wheels (normally mounted in a trailing truck). Examples of this type of locomotive were built by Wilhelm von Engerth.
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Great Northern Railway 2-8-8-0 Class N-1 locomotive, built at the Baldwin Locomotive Works in August 1912. In the Whyte notation for the classification of steam locomotives by wheel arrangement, a 2-8-8-0 is a locomotive with a two-wheel leading truck, two sets of eight driving wheels, and no trailing truck.
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An 0-8-6, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a locomotive with no leading wheels, eight driving wheels (4 axles) fixed in a rigid frame, and six trailing wheels (normally mounted in a trailing truck). Examples of this type of locomotive were built by Wilhelm von Engerth.
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It left the shop on May 29 and was sent to the Willmar, Minnesota division for passenger work. The following January, it was back in the shop to receive a booster engine on its trailing truck. This was removed in 1929. It was renumbered again, to 1355, in April 1926 and converted from coal to oil.
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Superficially similar to the Mason Bogie is another design, the Forney locomotive. Like the Mason Bogie, the Forney has powered axles under the boiler and a trailing truck under the rear bunker and tank behind the cab. However, the Forney's driving wheels are fixed in the frame, rather than articulated. They were reasonably popular, particularly on elevated railroads.
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The X class was, however, not considered to be a true Mountain type, since its trailing truck served to spread the axle load rather than to allow a larger and wider firebox. The trailing wheels were positioned well behind a narrow firebox, which itself sat above the coupled wheels, necessitating the same design compromise between coupled wheel diameter and grate size as on a Consolidation or Mastodon. A true design was a progression of the classic 4-6-2 Pacific layout, which featured a wide firebox positioned above the trailing truck and behind the coupled wheels, allowing for a wide and deep firebox as well as large coupled wheels. In 1909, the NGR placed the world's first true Mountain type locomotive in service when five Class Hendrie D tender locomotives were commissioned.
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Booster engine with the cover removed to show the mechanism. The driven axle is on the right; the booster normally hung behind it. Diagram showing how a booster is installed and connected. A booster engine for steam locomotives is a small two-cylinder steam engine back-gear-connected to the trailing truck axle on the locomotive or the lead truck on the tender.
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The Canadian Pacific Railway built two classes of 4-4-4 "Jubilee" locomotives. Both were semi-streamlined, in a similar fashion to the 4-6-4 "Royal Hudson" and 2-10-4 "Selkirk" locomotives. The F2a was styled after the Milwaukee Road "Hiawatha" "Atlantic", but with a four-wheel trailing truck to support a longer firebox. Class F2a consisted of five locomotives, Nos. 3000-3004.
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Under the Whyte notation for the classification of steam locomotives, 0-8-2 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles, and two trailing wheels on one axle (usually in a trailing truck). Other equivalent classifications are: UIC classification (also known as German classification and Italian classification): D1, French classification: 041, Turkish classification: 45, Swiss classification: 4/5.
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It has six relatively small driving wheels and large cylinders, making it extremely powerful for its size and is also known for its European-style high-pitched whistle. A two-wheel trailing truck supports the firebox and cab. Generating tractive effort of 10,600 pounds it has almost twice the pulling power of 119, and typically operates with a train consisting of six open-air coaches and a caboose.
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N 110, in an official VR photograph c.1936, shows a dramatically altered appearance after being equipped with Modified Front End and booster engine. In 1927, class leader N 110 was equipped with a two-cylinder Franklin booster engine which drove the trailing truck axle. Based on the success of this device, VR built all but two of the much larger X class 2-8-2s with booster engines.
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This was achieved by increasing the size of grate and firebox without changes to the rest of the locomotive, requiring the addition of a second axle to the trailing truck. Freight s became s while s became s. Similarly, passenger s became s. In the United States this led to a convergence on the dual-purpose and the articulated configuration, which was used for both freight and passenger service.
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The Texas wheel arrangement originated and was principally used in the United States of America. The evolution of this locomotive type began as a Santa Fe type with a larger four-wheeled trailing truck that would allow an enlarged firebox. A subsequent development was as an elongated Berkshire type that required extra driving wheels to remain within axle load limits. Examples of both of these evolutionary progressions can be found.
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An 0-4-4-0 of the metre gauge C. de F. de Madagascar. Baldwin Locomotive Works #44609, built December, 1916. In the Whyte notation for the classification of steam locomotive wheel arrangement, a 0-4-4-0 is a locomotive with no leading truck, two sets of four driving wheels, and no trailing truck. Examples of this type were constructed as Shay, Heisler, Climax, Mallet, Meyer, BMAG and Double Fairlie locomotives.
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14 but featured a longer boiler with a wider, larger grate, mounted above the frames and supported by a trailing truck. This enabled possible gauge conversion without radical re-engineering of the frames and grate. Despite these design features, no N class locomotive ever ran on standard gauge. By the time the standard gauge Albury to Melbourne mainline opened alongside the existing broad gauge line in 1962, steam locomotives were rapidly being withdrawn from service.
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In May 1928, 506 was experimentally fitted with a booster, included in a newly created four wheel trailing truck. This American-inspired modification proved highly successful, increasing the locomotive's tractive effort from to . This modification was subsequently fitted to the nine remaining locomotives, resulting in the class becoming the 4-8-4 class 500B. Throughout the mid-1930s all but two of the locomotives in the class were semi-streamlined and had valances fitted.
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The three-axle trailing truck supporting the firebox was unusual, carrying over 190,000 lbs, allowing the huge firebox needed for the high power. As it turned out, steam locomotives continued in service for almost another 20 years. Gene Huddleston's book, "C&O; Power", reports tests of the C&O; with a dynamometer car indicating momentary readings of with readings between at about . The state of calibration of the dynamometer car is not known.
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The WMR ordered No.17 from the Baldwin Locomotive Works. It entered service on 10 June 1902 and was at the time the most powerful locomotive to operate in the country. No.17 was the only 2-8-2 "Mikado" to run in New Zealand. It was a Vauclain compound, and its trailing truck bore similarities to the Q class, the world's first 4-6-2 "Pacific" type then under construction by Baldwin for NZR.
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No other members of the 3800 class have been documented with four-wheel trailing trucks. No. 3829 was scrapped in 1955, still equipped with a four-wheel trailing truck. ATSF No. 5000 Madame Queen Santa Fe, who had originated the type, adopted it again in 1930 with No. 5000, nicknamed Madame Queen. This locomotive was similar to the C&O; T-1, with the same drivers but with boiler pressure and 60% limited cutoff.
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The Kerr, Stuart designs are typified by having a single trailing truck (allowing a large firebox to be placed behind the driving wheels) and/or having a saddle tank. Several designs of side tank locomotive were produced that shared a chassis and boiler with a saddle tank design and it is not unknown for a standard chassis from one design to be used with a different design's standard boiler to produce a locomotive to suit a customers special requirements.
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Some modifications were made to the design for these PRR War Babies. These included PRR drop-couplers, sheet steel pilots, PRR-style cabs, large PRR tenders, Keystone number plates up front and other modifications. It still betrayed its foreign heritage by lacking the PRR trademark Belpaire firebox and by having a booster engine on the trailing truck. Altogether 125 locomotives were built between 1942 and 1944 and became the largest fleet of Texas type locomotives in existence.
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In a later variant, Bowen added a booster to the trailing truck, enabling the Selkirk to exert nearly 50% more tractive effort than the similar-sized K-1a Northern. When it was demonstrated that a three-unit EMD F3 diesel-electric consist that weighed slightly less than the total engine and tender mass of a CPR K-1a Northern could produce nearly three times its tractive effort, High powered steam locomotives were retired as quickly as finance allowed.
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The successful design of a trailing truck with the firebox mounted behind the driving wheels had not yet been developed. Wootten instead mounted his huge firebox above the locomotive's driving wheels. The problem now arose that with a cab floor at the then standard tender deck height, it would be impossible for the locomotive's engineer (driver) to see forwards around the firebox shoulders. Instead, a cab for the engineer was placed above and astride the boiler.
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A 4-4-4-4 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, has a four-wheel leading truck, two sets of four driving wheels, and a four-wheel trailing truck. While it would be possible to make an articulated locomotive of this arrangement, the only 4-4-4-4s ever built were duplex locomotives--with two sets of cylinders driving two sets of driven wheels in one rigid frame, essentially a 4-8-4 with divided drive.
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To provide enough heating surface to generate sufficient steam through its projected use the firebox was made wider for greater burning capacity. The two wheel trailing truck enabled the fitting of a wide firebox, necessary for a coke burning locomotive. The engine was originally fitted with the surplus tender from PB15 N° 411 after it was converted to a one off member of the 6D15 class. The tender was later changed to a standard C16 class locomotive tender to increase its potential range.
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The E6 was designed by the Pennsy's General Superintendent of Motive Power, Lines East, Alfred W. Gibbs, and his team. They produced an Atlantic of modern design, featuring a large and free-steaming boiler, outside Walschaert valve gear, piston valves on the cylinders, and a cast steel KW pattern trailing truck designed by the PRR's Chief Mechanical Engineer, William F. Kiesel, Jr. Modern features never present on the E6 design, and never retrofitted, included the mechanical stoker, power reverse and feedwater heater.
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The final two locomotives Nos. 6256 and 46257 Sir William A. Stanier, F.R.S and City of Salford were given many new features. In order to raise the mileage between general overhauls from 70,000 to 100,000, measures were taken to decrease wear to the axle bearings and hornguides through the use of roller bearings and manganese steel linings. Other modifications included further superheating area, a redesigned rear frame and cast steel trailing truck, rocking grate, hopper ashpan and redesigned cab-sides.
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The North London Railway crane tank was an steam locomotive crane tank type. Originally built in 1858 as an by Sharp Stewart and Company for the North and South Western Junction Railway. It was quickly passed to the North London Railway (NLR) who numbered it 37; they renumbered it 29 in 1861 before placing it on the duplicate lst as 29A in 1872. The same year it was rebuilt into an 0-4-2ST with a steam crane carried by the trailing truck.
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The Duluth, Missabe and Iron Range Railway hauled iron ore in Minnesota. Iron ore is heavy and the DM&IR; operated long trains of ore cars, requiring maximum power. These locomotives were based upon ten 2-8-8-2s that Baldwin had built in the 1930s for the Western Pacific Railroad. The need for a larger, coal-burning firebox and a longer, all-weather cab led to the use of a four-wheel trailing truck, giving them the "Yellowstone" wheel arrangement.
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The type was revived in 1925 by the Lima Locomotive Works. This time it was an expansion of the Berkshire type that Lima had pioneered. A version of the Berkshire with ten driving wheels instead of eight was an obvious development and the first to be delivered were to the Texas and Pacific Railway, after which the type was subsequently named. The four-wheel trailing truck allowed a much larger firebox and thus a greater ability to generate heat, and thus steam.
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Introduced from 1939, they were also built in NZR workshops, most of them with streamlined shrouding to cover the external pipe work of their feedwater heater systems. The first 35 locomotives were designated KA class and worked on the North Island mainlines with the older K class locomotives. Six more were built, designated KB class, for service on the steeply graded Midland line on the South Island. These locomotives were equipped with trailing truck boosters, which raised their tractive effort by .
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Part of this evolution involved increasing the size of the Mikado's firebox. This larger firebox improved the engine's coal burning efficiency, however the additional weight facility adding the second wheel set to the trailing truck. But steam engines were phased out in favor of diesel locomotives in the mid-20th century. This locomotive has the distinction of being the last Frisco steam locomotive in regular service, completing its final run (a five-mile trek from Bessemer to Birmingham, Alabama) on February 29, 1952.
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The C.P. Huntington The engine C.P. Huntington was one of three identical 4-2-4 tank locomotives. They were the first locomotives to be purchased by Southern Pacific Railroad in 1863, for use on light commuter services in the Sacramento area. The locomotives had serious shortcomings. The single driving axle did not carry the full weight of the engine's rear end due to the trailing truck and, in addition to being too light, it therefore lacked adhesion to reliably pull trains, especially on gradients.
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AT&SF; 2-10-2 No. 3932 In the United States, the type was produced between 1903 and 1930. The first were the Atchison, Topeka and Santa Fe Railway (AT&SF;) engines of the 900 and 1600 series, which were an early type with few advantages over the 2-10-0 Decapod, save their ability to operate in reverse without derailing. By 1919, the AT&SF; was building the definitive type, with the trailing truck supporting a large firebox. These were of the AT&SF; 3800 class.
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One of them, AT&SF; engine no. 3829, was equipped with an experimental two-axle trailing truck to become the first 2-10-4 Texas type. USRA light 2-10-2 Santa Fe About 2,200 Santa Fe types were built, including about 500 of the two United States Railroad Administration (USRA) First World War standard designs. There were two USRA standard , the heavy version with an engine weight of and the light version with an engine weight of . The Santa Fe had the most with 352 engines.
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Lima Locomotive Works' conception of superpower steam as realized in the 2-8-4 Berkshire type was the predecessor to the Hudson. The 2-8-4's 4-wheel trailing truck permitted a huge firebox to be located after the boiler. The resulting greater steaming rate ensured that such a locomotive would never run out of power at speed, a common failing of older locomotives. Applying the ideas of the freight-minded Berkshire type to the Pacific resulted in a 4-6-4 locomotive.
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ALCO-built 2-6-6 suburban tank locomotive of the New York Central and Hudson River Railroad. In the Whyte notation for describing steam locomotive wheel arrangement, a 2-6-6 is a locomotive with a two-wheeled leading truck, six driving wheels, and a six-wheeled trailing truck. All the locomotives produced of this arrangement have been tank locomotives, and the vast majority in the United States. It was a popular arrangement for the larger Mason Bogies, as well as some of the largest suburban tank locomotives.
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These locomotives were originally numbered 3800–3999. They were renumbered between 1920 and 1929 renumbered to the 3600 and 3700s. Most of the class were converted to oil-firing in the later years. In the 1920s onward Canadian Pacific saw an increasing need for larger locomotives. Most of this class were relocated to either CP's Ogden or Montreal shops for a short time while 65 were converted to Class P1n 2-8-2 renumbered 5200-5264 in 1946 a larger boiler was added as well as a trailing truck and a new cab.
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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, is an articulated locomotive using a pair of power units back to back, with the boiler and cab suspended between them. The 2-6-2 wheel arrangement has a single pair of leading wheels in a leading truck, followed by three coupled pairs of driving wheels and a pair of trailing wheels in a trailing truck. Since the 2-6-2 type was often called the Prairie type, the corresponding Garratt and Modified Fairlie types were usually known as a Double Prairie.
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It remained this way until after the National Park Service took over Steamtown in 1987 when it was repainted into the livery it wore in active service with Canadian Pacific. 2317 was present at the grand opening of Steamtown National Historic Site along with Baldwin Locomotive Works 26 and Canadian National 3254 and ran several excursions on the former Lackawanna main line. 2317 then settled down and would often pull Steamtown's excursions in tandem with 3254 until 2004 when problems with its trailing truck, dry pipe and tires were found.
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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a is an articulated locomotive using a pair of power units back to back, with the boiler and cab suspended between them. The 2-8-2 wheel arrangement has a single pair of leading wheels in a leading truck, followed by four coupled pairs of driving wheels and a pair of trailing wheels in a trailing truck. Since the 2-8-2 type was known as Mikado, the corresponding Garratt and Modified Fairlie types were usually known as Double Mikado.
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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a ' is a Garratt articulated locomotive. The wheel arrangement is effectively two 4-4-2 locomotives operating back to back, with each power unit having four leading wheels on two axles in a leading bogie, four powered and coupled driving wheels on two axles, and two trailing wheels on one axle in a trailing truck. Since the 4-4-2 type is usually known as an Atlantic', the corresponding Garratt type is often referred to as a Double Atlantic.
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The intent was to eliminate helper requirements on grades, and thus a locomotive larger than the Union's previous switchers and 2-8-0 "Consolidations" was needed. Ten driving wheels allowed the application of sufficient tractive effort within the axle load limits of the line, and the requirement for a large firebox and plentiful steam-raising ability necessitated the trailing truck. To increase tractive effort still further, a booster engine was fitted to the leading tender truck. The unusual wheel arrangement was also a result of the turntable restrictions on the total wheel base.
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The new boiler design also featured a combustion chamber and thermic syphons to increase power and efficiency. The VR was so satisfied with the performance of the revised X class all-steel boiler design, a shortened barrel version was considered during the design phase of the R class 4-6-4 express passenger locomotives of 1951. X38 introduced a new welded fabricated trailing truck in place of the cast steel units previously imported from the Commonwealth Steel Company of Illinois, USA. This design innovation was fitted to all subsequent examples built.
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Although they were now more powerful than the F class and were reasonably successful, the FA class was hampered like the LA 4-4-0T rebuilds in that their coal bunkers were too small. The decision was made in 1897 to extend the frames of F 9, then undergoing conversion at Addington Workshops, and fit an extended coal bunker. To accommodate this, a two-wheeled trailing truck would be added. Initially, FA 9 was classified as an FB class locomotive to differentiate it from the 0-6-0T conversions.
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It spent its first ten years near Hillyard, Washington and then in 1919, was sent to Spokane, both in passenger service. On February 19, 1924, it returned to the Dale Street Shops for a major rebuild. It's not clear whether this was actually a rebuild or virtually a new engine. New parts included a Belpaire firebox, longer boiler, type A superheater, new solid leading wheels, a Delta trailing truck which made it a 4-6-2, new brakes, and one of its four conversions between oil and coal fuel.
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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a is a Garratt articulated locomotive consisting of a pair of engine units back to back, with the boiler and cab suspended between them. The wheel arrangement has four leading wheels on two axles, usually in a leading bogie, eight powered and coupled driving wheels on four axles and two trailing wheels on one axle, usually in a trailing truck. Since the type is generally known as a Mountain, the corresponding Garratt type is usually known as a Double Mountain.
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Surviving GS-4 4449 was equipped with roller bearings on the lead truck, trailing truck and tender (But not the main axles or rods) in 2008 and therefore shares some of the same characteristics as a GS-5. The roller bearings on the two GS-5's were so successful that when both #4458 and #4459 were scrapped, they were examined and showed minimal wear. Locomotive #4458 was known as the pinnacle of steam power on the Southern Pacific Lines, and lasted in service the longest, pulling the ever popular Valley Daylight until late 1956.
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Norfolk & Western #578 is a 4-6-2 "Pacific" E2a steam locomotive built in March 1910 by the American Locomotive Company's Richmond Works. The full length including the tender is . The weight fully loaded is 285 tons (259 t). The 6 sets of wheels from front to back are two sets of wheels for the pilot truck, 3 sets of wheels for the drivers, and one set of wheels for the trailing truck. The tender has 2 Buckeye steel built 6 wheel trucks each wheel at 33 inches. The full height of the locomotive is The fuel capacity is 26 tons of coal and 18,000 U.S. gallons (68,000 L) of water. This locomotive was donated to the Ohio Railway Museum on Thursday, February 12, 1959 from the Norfolk and Western Railway Company. Norfolk & Western #578 is the last surviving one of 26 E2a locomotives built for the Norfolk and Western Railway Company. Numbers 553-558 were built by the Baldwin Locomotive Works while numbers 559-563 were built by the Norfolk & Western shops at Roanoke and numbers 564-579 were built by Alco's Richmond Works. The 4-6-2 designation indicates that there are four wheels in the pilot truck, six driving wheels, and two wheels in the trailing truck.
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It had one Martin Blomberg-designed E-unit A1A passenger truck at the front, with powered outer axles and a center idler axle, and an unpowered trailing truck, giving it the unusual wheel arrangement of A1A-2. This made it mechanically half of an E3. The back half of the power car was a baggage area. This made it similar to special power- baggage units built by EMD for the Colorado Springs section of the Chicago, Rock Island and Pacific "Rocky Mountain Rocket", though the latter had a carbody and E-3/E-6 styling by EMD.
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The M1 was a class of steam locomotive of the Pennsylvania Railroad (PRR). It was a class of heavy mixed-traffic locomotives of the 4-8-2 "Mountain" arrangement, which uses four pairs of driving wheels with a four-wheel guiding truck in front for stability at speed and a two-wheel trailing truck to support the large firebox needed for sustained power. Although built for both passenger and freight work, they spent most of their service lives hauling heavy high-speed freight trains. Many PRR men counted the M1 class locomotives as the best steam locomotives the railroad ever owned.
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A USRA standard 2-8-8-2. A 2-8-8-2, in the Whyte notation for describing steam locomotive wheel arrangements, is an articulated locomotive with a two-wheel leading truck, two sets of eight driving wheels, and a two-wheel trailing truck. The equivalent UIC classification is, refined to Mallet locomotives, (1'D)D1'. These locomotives usually employ the Mallet principles of articulation—with the rear engine rigidly attached to the boiler and the front engine free to rotate—and compounding. The 2-8-8-2 was a design largely limited to American locomotive builders.
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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the is a Garratt articulated locomotive. The wheel arrangement is effectively two 2-4-2 locomotives operating back to back, with the boiler and cab suspended between the two power units. Each power unit has a single pair of leading wheels in a leading truck, followed by two coupled pairs of driving wheels, with a single pair of trailing wheels in a trailing truck. Since the type is sometimes known as a Columbia, the corresponding Garratt type could be referred to as a Double Columbia.
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In the United States of America, the 2-8-4 wheel arrangement was a further development of the enormously successful United States Railroad Administration (USRA) 2-8-2 Mikado. It resulted from the requirement for a locomotive with even greater steam heating capacity. To produce more steam, a solution was to increase the size of the locomotive's firebox, but the 2-8-2 wheel arrangement with its single axle trailing truck limited the permissible increased axle loading from a larger firebox. The most practical solution was to add a second trailing axle to spread the increased weight of a larger firebox.
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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a is a Garratt or Union Garratt articulated locomotive using a pair of engine units back to back, with the boiler and cab suspended between them. The wheel arrangement of each engine unit has four leading wheels on two axles, usually in a leading bogie, six powered and coupled driving wheels on three axles, and two trailing wheels on one axle, usually in a trailing truck. Since the type is known as a Pacific, the corresponding Garratt type is usually known as a Double Pacific.
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David Joy, designer of the eponymous valvegear, described encountering these axleboxes on Webb's Precedent class. The earlier Adams design for a similar axle had relied on the axle and thrust- faces within the axle bearings to keep the hornblocks in position. In the 1920s, some electric locomotives used rigid frames with a leading and trailing truck, where a cannon bearing was a convenient inside-framed bearing for the truck. The Swiss 'Java bogie' design, developed by Jakob Buchli, even used this for a driving axle, with the drive provided by a one-sided Buchli drive outside the wheels.
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The wheel arrangement evolved in the United States from the 2-10-0 Decapod of the Atchison, Topeka and Santa Fe Railway (ATSF). Their existing 2-10-0 tandem compound locomotives, used as pushers up Raton Pass, encountered problems reversing back down the grade for their next assignments since they were unable to track around curves at speed in reverse and had to run very slowly to avoid derailing. Consequently, the ATSF added a trailing truck to the locomotives which allowed them to operate successfully in both directions. These first locomotives became the forerunners to the entire family.
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The trailing truck allows a larger, deeper firebox than that of a . Like all ten- coupled designs, the long rigid wheelbase of the coupled wheels presented a problem on curves, requiring flangeless drivers, lateral motion devices and much sideplay on the outer axles. To limit this problem, the coupled wheels were generally small, up to in diameter, which in turn generated the problem of insufficient counterweights to balance the weight of the driving rods.pp.92, 138, 148-149, 172-173, 192-193 The 's inherent problem was the low speed restriction on the type, which was about .
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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, ' represents a configuration of four leading wheels on two axles, usually in a leading bogie with a single pivot point, four powered and coupled driving wheels on two axles, and two trailing wheels on one axle, usually in a trailing truck which supports part of the weight of the boiler and firebox and gives the class its main improvement over the configuration. This wheel arrangement is commonly known as the Atlantic type, although it is also sometimes called a Milwaukee or 4-4-2 Milwaukee, after the Milwaukee Road, which employed it in high speed passenger working.
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A 2-4-6-2 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, has a two-wheel leading truck, one set of four driving wheels, one set of six driving wheels, and a two-wheel trailing truck. Other equivalent classifications are: UIC classification: 1BC1 (also known as German classification and Italian classification) French classification: 1231 This most unusual wheel arrangement was only ever used on a duplex locomotive type. Ten 2-4-6-2 (151A) compound locomotives were built in 1932 for the Paris-Lyons-Marseilles Railway (P.L.M.) to haul heavy freight trains on the 0.8% grade between Les Laumes and Dijon.
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A 4-6-0 camelback built for the Central Railroad of New Jersey by the Baldwin Locomotive Works John E. Wootten developed the Wootten firebox to effectively burn anthracite waste, which was a plentiful, cheap source of fuel. Wootten determined that a large, wide firebox would work best. As the successful trailing truck used to support large fireboxes had not yet been developed, Wootten instead mounted his huge firebox above the locomotive's driving wheels. The problem now arose that with a cab floor at the then standard tender deck height, it would be impossible for the locomotive's engineer to see forwards around the firebox shoulders.
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"Superpower steam" was a term coined by Lima Locomotive Works in the mid-1920s. It referred to steam locomotives with booster-equipped four-wheel trailing trucks supporting large fireboxes, as well as enlarged superheaters. The wheel arrangements introduced in the 1920s for these locomotives: the 4-6-4's, 2-8-4's, 4-8-4's and 2-10-4's, and in the 1930s, the 2-6-6-4's. The term "superpower" was often applied to all locomotives with 4 wheel trailing truck arrangements afterward, though many did not have boosters and almost all steam of any wheel arrangement built after that time had large superheaters.
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These numbers typically represented the number of unpowered leading wheels, followed by the number of driving wheels (sometimes in several groups), followed by the number of un-powered trailing wheels. For example, a yard engine with only 4 driven wheels would be categorised as a wheel arrangement. A locomotive with a 4-wheel leading truck, followed by 6 drive wheels, and a 2-wheel trailing truck, would be classed as a . Different arrangements were given names which usually reflect the first usage of the arrangement; for instance, the "Santa Fe" type () is so called because the first examples were built for the Atchison, Topeka and Santa Fe Railway.
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In August 2010, Tornado was to have visited the Bluebell Railway for its 50th anniversary of operation celebrations. The A1SLT had a preference for moving the engine to Sheffield Park by rail due to issues with the trailing truck potentially becoming damaged if the locomotive was transported by low-loader, but they would have been willing to move the engine by road if the Bluebell's extension was not completed in time for Tornado to visit, which it was not. However, repairs proved to be more extensive than previously thought, and the decision was made to withdraw the engine from the gala. However, in March 2013, the Bluebell Railway's extension was completed.
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These proved to be successful and were later used on other Bulleid classes. The leading bogie was based upon that of the SR Lord Nelson class, although it had a 6 ft 3 in (1.90 m) wheelbase as opposed to Maunsell's 7 ft 6 in (2.28 m) design, and featured 3 ft 1 in (0.94 m) BFB wheels. A long coupled driving wheelbase was incorporated into the design, to keep the locomotives within the lineal loading of the Southern Railway's narrower bridges. The supporting rear trailing truck was a one-piece steel casting that gave the smoothest of rides; the design was utilised in the future BR Standard Class 7.
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The 60 T tank engines of CSD 477 class represent the ultimate development of the CKD 4-8-2 tender locomotive, but added a four-wheel trailing truck as part of the conversion to a tank locomotive. One of five classes of three cylinder locomotives known, they were the last steam locomotives delivered to the Czechoslovak State Railways, with the last group built in 1955. Used primarily in local passenger service, they were pulling regularly timetabled trains as late as 1991. CSD 477.043 in the Railway Museum at Lužná u Rakovníka Three are preserved, as of 2018 two of them were still operational (013 and 043).
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Beattie was almost instantly faced with a problem upon appointment as Chief Mechanical Engineer: New Zealand's railway network was expanding, traffic volumes were growing, faster speeds were required, and accordingly, a more powerful type of locomotive was required.History of Technical Innovation in New Zealand – The Steam Railways Furthermore, although this new class was to haul the heaviest and fastest expresses, it was to burn low grade lignite coal from Canterbury and Otago. Baldwin Locomotive Works recommended a camelback design to solve the problem, but Beattie conceived the idea of an enhanced 4-6-0 UB class locomotive with a two-wheel trailing truck to support a wide Wootten firebox.Leitch, Railways of New Zealand, pg. 167.
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Canadian National 3377 is a preserved class "S-1-d" 2-8-2 "Mikado" type steam locomotive currently on display at the Steamtown National Historic Site in Scranton, Pennsylvania. After being retired, the locomotive was sold to the Edaville Railroad in September 1961, and then was later moved to Bellows Falls, Vermont and became part of the Steamtown, U.S.A. collection in 1969. Unfortunately, the 3377 was the target of copper thieves during her trip to Steamtown, it was never repaired and has been cannibalized for parts for Steamtown's operating Canadian National 2-8-2, the 3254. Even the pilot wheels and trailing truck were removed, making it an oversized 0-8-0.
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A very large fire-grate area was provided, which gave the locomotive free-steaming qualities; its grate area was in fact larger than many later express passenger locomotives. Only the Baden IV h 4-6-2 and DRG Class 45 2-10-2 locomotives ever had larger fireboxes in Germany; even the record-breaking DRG Class 05 4-6-4s had fireboxes no larger than the S 2/6. This was partly because Bavarian coal was of lower quality than that available in Prussia and elsewhere. Large ashpans extended down on both sides of the locomotive, between the driving wheels and trailing truck, allowing for long runs before they needed to be emptied.
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The S class also showed American design influence in its use of a delta trailing truck and bar frames rather than plate frames. Built at Victorian Railways' Newport Workshops, the S class locomotives were, at the time of construction of the first three, the largest locomotives to have been built in Australia, and had the largest boilers to have yet been constructed in the southern hemisphere.Dunn et al., Super Power on the VR – Part 1, p. 6 Another notable design innovation, the incorporation of all three cylinders and the smokebox saddle into a single casting, was the first of its type in the southern hemisphere and one of the largest single castings yet undertaken in Australia.
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After the success of the original locomotives, ten more 700 class locomotives, with larger tenders, were locally built using the facilities of the new Islington Workshops. These were the 710 class. The 500 class was rated to haul 400 tons over the Mount Lofty Ranges immediately east of Adelaide, where a continuous 1-in-45 (2.2%) gradient faced trains heading for Victoria. Two years after their introduction, the class was modified by the addition of a booster engine which required replacement of the two-wheel trailing truck with a four-wheel truck. This altered the wheel arrangement from 4-8-2 to 4-8-4, but the term "Mountains" stuck with the locomotives.
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The X class was a development of the earlier C class 2-8-0 goods locomotive, designed to be gauge convertible from to in the event of the Victorian Railways network being converted to standard gauge. The C class, with a narrow firebox between the frames, could not be easily converted. The X class retained the same cylinder and driving wheel dimensions as the C class as well as its valve gear, but introduced a much larger boiler and a trailing truck behind the rear driving axle. The 2-8-2 layout of the X class allowed a wide, deep firebox suited to the high ash, low calorific coals from the State Coal Mine typically used for goods haulage.
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Chesapeake & Ohio Railway 2755 is a standard gauge steam railway locomotive of the 2-8-4 type, called "Berkshire" by most US railroads, but "Kanawha" by the Chesapeake & Ohio (C&O;). It is one of a total of ninety built by ALCO (which built seventy) and Lima (which built the remaining twenty, including 2755) between 1943 and 1947. A Berkshire type was the first of the Lima Super Power locomotives in 1925 and these followed in that tradition, with all the latest equipment -- Schmidt superheater, Elesco feedwater heater, booster on the trailing truck, roller bearings, and so forth. They carried Baker valve gear, which the C&O; preferred to the simpler and much more widely used Walschaerts valve gear.
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The firebox could also be longer and wider, increasing the heating surface area and steam generation capacity of the boiler, and therefore its power. The concept was soon improved to provide radial lateral movement by placing the pair of trailing wheels and their axle in a fabricated sub-frame or truck, usually with outside bearings as they gave the best lateral riding stability. One- piece cast-steel trailer trucks were developed about 1915, to provide the additional strength for a booster engine to be fitted to the trailing axle. Finally, about 1921 the Delta trailing truck was developed with an inverted- rocker centering device at the rear ends of the truck frame.
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Southern Pacific 4294, preserved at the California State Railroad Museum in Sacramento, California. Under the Whyte notation for the classification of steam locomotives, a 4-8-8-2 is a locomotive with four leading wheels, two sets of eight driving wheels, and a two-wheel trailing truck. Other equivalent classifications are: UIC classification: 2DD1 (also known as German classification and Italian classification) French classification: 240+041 Turkish classification: 46+45 Swiss classification: 4/6+4/5 The equivalent UIC classification is refined to (2'D)D1' for Mallet locomotives. A locomotive of that length must be an articulated locomotive; meaning all have a joint between the first and second groups of driving wheels.
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The Pennsylvania Railroad's class S2 was a steam turbine locomotive designed and built in a collaborative effort by Baldwin Locomotive Works and Westinghouse Electric & Manufacturing Company, as an attempt to prolong the dominance of the steam locomotive by adapting technology that had been widely accepted in the marine industry. One was built, #6200, delivered in September 1944. The S2 was the sole example of the 6-8-6 wheel arrangement in the Whyte notation, with a six-wheel leading truck, eight driving wheels, and a six- wheel trailing truck. The S2 used a direct-drive steam turbine provided by the Westinghouse Electric & Manufacturing Company, geared to the center pair of axles with the outer two axles connected by side rods; the fixed gear ratio was 18.5:1.
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There was little opportunity to exploit their high speed capability. Furthermore, their relatively low factor of adhesion (4.08) and lack of fully compensated springing, coupled with the tendency of locomotives to transfer weight to the rearmost wheels under high drawbar pull conditions (which in the case of the R meant a weight transfer from the driving wheels to the unpowered trailing truck) caused them to slip when starting heavy goods trains. The R class is remembered by many for its role as power for the seasonal grain harvest. In times of a good harvest, virtually every available locomotive would be marshalled into service to shift wheat trains of over 1,000 tons from Victoria's Western district through to the ports for export.
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While the wheel arrangement and type name Atlantic would come to fame in the fast passenger service competition between railroads in the United States by mid-1895, the tank locomotive version of the Atlantic type first made its appearance in the United Kingdom in 1880, when William Adams designed the 1 Class T of the London, Tilbury and Southend Railway (LT&SR;). The is the tank locomotive equivalent of a 4-4-0 American type tender locomotive, but with the frame extended to allow for a fuel bunker behind the cab. This necessitated the addition of a trailing truck to support the additional weight at the rear end of the locomotive. As such, the tank version of the wheel arrangement appeared earlier than the tender version.
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VR also modified the design of the Delta trailing truck on the second (1930-31 built) batch of N class locomotives to enable easy retrofitting of booster engines. Despite this, no further boosters were ever fitted, and in 1945, N 110's booster was removed and fitted to one of the two non-booster equipped X class locomotives. In 1936, class leader N 110 was again selected to test new features, this time a series of design changes for improved drafting and reduced cylinder back pressure referred to as 'Modified Front End' which had already been successfully applied to the C class locomotive. N 110's performance was dramatically improved, and all the original thirty N class locomotives were similarly equipped.
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The railroad and its predecessors would roster a total of eight steam locomotives over the years, all bought second hand and none with a trailing truck. Three of these were camelback locomotives and the wheel arrangements included 4-4-0, 2-6-0, 4-6-0, and 2-8-0. The line's predecessor, the Middletown and Unionville Railroad (M&U;), relied on the nearby New York, Ontario and Western shops for locomotive repairs and inspections and rented fifty-six different O&W; locomotives in thirteen classes while its own was in the O&W; shops. On April 23, 1944, the M&U; retired the last railroad-owned steam locomotive and thereafter leased O&W; locomotives and then NYS&W; 2-10-0 "decapod" steam locomotives.
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An article appearing in a 2008 issue of the Pennsylvania Railroad Technical and Historical Society Magazine showed that inadequate training for engineers transitioning to the T1 may have led to excessive throttle applications, resulting in driver slippage."In Defense of the 5500s", Volume 41, Number 1, Pennsylvania Railroad Technical and Historical Society Magazine, Spring, 2008 Another root cause of wheelslip was faulty "spring equalization": The stiffnesses of the springs supporting the locomotive over the axles were not adjusted to properly equalize the wheel-to-track forces. The drivers were equalized together but not equalized with the engine truck. In the production fleet the PRR equalized the engine truck with the front engine and the trailing truck with the rear engine, which helped to solve the wheelslip problem.
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It was designed by Hendrie to handle coal traffic on the upper Natal mainline and, while it was based on the Class Hendrie B , it had the firebox positioned to the rear of the coupled wheels to make a larger grate and ashpan possible. To accomplish this, the plate frame was equipped with a cast bridle at the rear to accommodate the improved firebox design, which also necessitated the addition of a trailing truck. Five locomotives were built by the North British Locomotive Company and delivered in 1909. The type went on to become the most widely used steam locomotive wheel arrangement in South Africa, with altogether thirty classes of both tank and tender versions eventually seeing service on the South African Railways.
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The Union Pacific Big Boy is a type of simple articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service until 1959. The 25 Big Boy locomotives were built to haul freight over the Wasatch mountains between Ogden, Utah, and Green River, Wyoming. In the late 1940s, they were reassigned to Cheyenne, Wyoming, where they hauled freight over Sherman Hill to Laramie, Wyoming. They were the only locomotives to use a 4-8-8-4 wheel arrangement: four-wheel leading truck for stability entering curves, two sets of eight driving wheels and a four-wheel trailing truck to support the large firebox.
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In the Whyte notation for describing steam locomotive wheel arrangement, a 2-8-6 is a locomotive with a two-wheel leading truck, eight driving wheels, and a six-wheel trailing truck. All 2-8-6 locomotives constructed have been 2-8-6T tank locomotives of the Mason Bogie pattern. Other equivalent classifications are: UIC classification: 1D3 (also known as German classification and Italian classification) French classification: 143 Turkish classification: 48 Swiss classification: 4/8 In the UIC classification as applied in Germany and Italy, a rigid-framed locomotive of this arrangement would be 1'D3', and the Mason bogie (1'D)'3'. Three Mason Bogies of this type were built for the Denver, South Park and Pacific Railroad; #25 Alpine, #26 Rico, #27 Roaring Fork and #28 Denver.
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Under the Whyte notation for the classification of steam locomotives, ' represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, eight powered and coupled driving wheels on four axles and two trailing wheels on one axle, usually in a trailing truck. This configuration of steam locomotive is most often referred to as a Mikado', frequently shortened to Mike. At times it was also referred to on some railroads in the United States of America as the McAdoo Mikado and, during the Second World War, the MacArthur. The notation 2-8-2T indicates a tank locomotive of this wheel arrangement, the "T" suffix indicating a locomotive on which the water is carried in side-tanks mounted on the engine rather than in an attached tender.
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This improved on some key shortcomings of the C class which were regarded as poor steaming and featured a very long manually stoked firebox that was difficult to fire and prone to clinkering. The X class was also equipped with a much larger capacity tender of similar design to the S class Pacific introduced in 1928, enabling through runs from Melbourne to Bendigo without intermediate stops to restock the tender. All but two were built with a Franklin C2 type Booster engine on the trailing truck axle, following a successful trial of a booster on the smaller N class light lines 2-8-2. The booster allowed an additional tractive effort at starting and low speeds to increase the hauling power of the locomotive, particularly on heavy grades.
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In the 1920s the Pennsylvania Railroad needed a locomotive for commuter trains. When the first G5s rolled out of the Juniata shops in 1923, the Pennsylvania Railroad hadn't built a 4-6-0 in more than two decades. Mechanical Engineer William F. Kiesel, Jr. who designed the engine used the boiler from an E6s Atlantic and designed one of the largest and most powerful ten-wheelers ever built. Smaller drive wheels than an Atlantic and the lack of a trailing truck put more weight on the drivers and produced an engine with great power and acceleration but a lower top speed. The 4-6-0 wheel arrangement could provide sufficient tractive effort, (41,000 lbs of tractive force) but at the same time, allow the locomotive to accelerate the train more quickly.
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Over time, freight locomotive size increased, and the overall number of axles increased accordingly; the leading bogie was usually a single axle, but a trailing truck was added to larger locomotives to support a larger firebox that could no longer fit between or above the driving wheels. Passenger locomotives had leading bogies with two axles, fewer driving axles, and very large driving wheels in order to limit the speed at which the reciprocating parts had to move. In the 1920s, the focus in the United States turned to horsepower, epitomised by the "super power" concept promoted by the Lima Locomotive Works, although tractive effort was still the prime consideration after World War I to the end of steam. Goods trains were designed to run faster, while passenger locomotives needed to pull heavier loads at speed.
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Tornado in steam at Darlington Locomotive Works, 8 August 2008 After leaving the GCR, it is intended that Tornado will, as much as possible, not be transported by road; therefore she will only see service on the main line, or on heritage lines with a main line connection. Exceptions have been made to this: the locomotive revisited the GCR in spring 2010, and was to have been transported by road to the Bluebell Railway in August 2010.Despite Tornado being booked to attend the Bluebell Silver Jubilee, the decision was made not to attend due to the risk of damaging the locomotive's trailing truck. The Bluebell does not yet have its mainline connection, which was scheduled to open in 2013 with the completion of the Northern Extension from Kingscote to East Grinstead (Bluebell Rly).
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Mason's idea was to remove what American railroad men saw as the biggest disadvantages of the Fairlie - its cramped space for fuel and water caused by its double ended design (not very useful on American railroads where there was always ample room for a turntable or wye), its cramped cab caused by the joined double boilers, and to some degree its poor riding. He did this by removing one boiler of the double Fairlie and retaining only one power truck at the front. A much larger cab was fitted, and a fuel bunker and water tank behind the cab, supported by a trailing truck. The advantages of the Fairlie design were kept; the swivelling driven truck for a greater ability to negotiate curves, and the large open space between the trucks to fit a large firebox unrestricted by the wheels.
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Success returned to Lima in the 1920s with the new concept of "Super Power" developed by Lima's mechanical engineer William E. Woodard. By making a number of significant changes to maximize a steam locomotive's capacity to generate and utilize steam, Woodard was able to make such locomotives significantly more powerful and faster. He did this by starting in 1922 with the H-10 experimental heavy 2-8-2 design for the New York Central (Michigan Central 8000) and applying both relatively new science (the Cole ratios), and every efficiency-enhancing tool available – a larger firebox, increased superheat, a feedwater heater, improved draughting, higher boiler pressure, streamlined steam passages and a trailing-truck booster engine, and by applying limited cutoff (the range of steam valve admission settings) to prevent locomotive engineers from using excessive steam at starting. The 2-8-2 thus produced was demonstrated to be 26% more efficient overall than its immediate predecessor, and the NYC bought 301 locomotives.
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Due to the troubles faced with the Garratts in their original form, a proposal was put forward in late 1935 for the three Garratts to be dismantled and the engine units used to build six new 4-6-2 tender locomotives. The three locomotives were dismantled at Hutt Workshops in 1936 and the engine units shipped to Hillside Workshops in Dunedin for eventual rebuilding. The engines as rebuilt were fitted with a new third cylinder, a modified AB class boiler, a new cab and trailing truck based on those used on the Baldwin AA class, and a new Vanderbilt tender based on those used on the AB class, but of welded construction and fitted with roller bearing bogies. The original plate frames were retained as was the Gresley conjugated valve gear. The first rebuilt locomotive, G 96, was outshopped on 8 September 1937 and dispatched north after initial tests to Christchurch for use on the Midland line.
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On many railways worldwide, Pacific steam locomotives provided the motive power for express passenger trains throughout much of the early to mid-20th century, before either being superseded by larger types in the late 1940s and 1950s, or replaced by electric or diesel-electric locomotives during the 1950s and 1960s. Nevertheless, new Pacific designs continued to be built until the mid-1950s. The type is generally considered to be an enlargement of the Atlantic type, although its prototype had a direct relationship to the Ten- wheeler and Prairie, effectively being a combination of the two types. The success of the type can be attributed to a combination of its four-wheel leading truck which provided better stability at speed than a Prairie, the six driving wheels which allowed for a larger boiler and the application of more tractive effort than the earlier Atlantic, and the two-wheel trailing truck, first used on the New Zealand Prairie of 1885.
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The poppet valves required less horsepower for fast operation and were able to distribute steam flow with precision valve operation when going at high speeds. The T1's were further burdened by excessive wheel slip on one of the two engine sets when the locomotive operated at high speed or when the engine started moving. The Pennsylvania Railroad tried to address the problem by changing the spring bed arrangement on the T1, from being a single bed that supported only the eight drivers, to two beds; the forward bed supporting the pilot truck and first engine and the aft bed supporting the second engine and trailing truck. Despite this, a permanent solution couldn't be found to ultimately prevent violent wheel slip, even though an "anti-slip" mechanism had been installed on the PRR Q2 class duplex. It is possible that the engineers, more familiar with the K4s class were better used to the slower throttle action of the K4s, whereas the T1 reacted more immediately to the engineer's throttle input due in part to the use of poppet valves.
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A 1914 picture of Reading Class M1sa showing the cab behind the wide Wootten Firebox, a first for the Reading Reading Railway 2-10-2 no. 3000 In 1900, the Reading Shops began construction along the Reading yards and North 6th Street, facilitating the maintenance and construction of a greater locomotive and rolling stock fleet. The shops were completed four years later, with their imposing brick architecture, they were the largest railroad shops in America, and unlike most railroads, allowed the Reading to make its own engines. They still stand today in non RR use. Larger steam locomotives were introduced to haul the increasing traffic, including the massive N1 class 2-8-8-2 (Chesapeake) Mallet, and Reading made one M1 class 2-8-2 freight hauler, Baldwin Locomotive Works built the rest. Big freight haulers were the massive K-1 2-10-2 locomotives, some were built in Reading, Pennsylvania from the Mallets, others were built by Baldwin. The G1 class 4-6-2 were passenger locomotives. These classes were an important break of tradition of the Readings motive power fleet. The M1s were the first Reading locomotives to include a trailing truck, and the first engine with the cab behind the Wootten firebox.
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Delta trucks were soon enlarged to carry four trailing wheels, and later six.Alfred W Bruce.(1952) The Steam Locomotive in America - Its Development in the Twentieth Century New York, U.S.A. : Bonanza Books. p239-40, 256-57 A "Delta" type trailing truck, fabricated using a one-piece casting by Commonwealth Steel Co. 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 Whyte notation the number designates the number of wheels rather than the number of axles, thus the final 2 in the Mikado's 2-8-2 refers to two wheels (one axle) while the Northern type's 4-8-4 designation refers to four wheels (two axles). The highest number of trailing wheels on a single locomotive is six as seen on 2-6-6-6 Allegheny type and the Pennsylvania Railroad's 6-8-6 steam turbine and 6-4-4-6 duplex locomotives, as well as numerous Mason Bogie locomotives.
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