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30-695: A bogie ( / ˈ b oʊ ɡ i / BOH -ghee ) (or truck in North American English) comprises two or more wheelsets (two wheels on an axle ), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes of transport. A bogie may remain normally attached (as on many railroad cars and semi-trailers ) or be quickly detachable (as for a dolly in a road train or in railway bogie exchange ). It may include suspension components within it (as most rail and trucking bogies do), or be solid and in turn be suspended (as are most bogies of tracked vehicles). It may be mounted on

60-714: A bogie (" truck " in North America ) – a pivoted frame assembly holding at least two wheelsets – at each end of the vehicle. Most modern freight cars and passenger cars have bogies each with two wheelsets, but three wheelsets (or more) are used in bogies of freight cars that carry heavy loads, and three-wheelset bogies are under some passenger cars. Four-wheeled goods wagons that were once near-universal in Europe and Great Britain and their colonies have only two wheelsets; in recent decades such vehicles have become less common as trainloads have become heavier. Most train wheels have

90-400: A conical taper of about 1 in 20 to enable the wheelset to follow curves with less chance of the wheel flanges coming in contact with the rail sides, and to reduce curve resistance . The rails generally slant inwards at 1 in 40, a lesser angle than the wheel cone . Without the conical shape, a wheel would tend to continue in a straight path due to the inertia of the rail vehicle, causing

120-479: A semi-trailer , whether permanently attached to the frame (as on a single trailer) or making up the dolly that can be hitched and unhitched as needed when hitching up a second or third semi-trailer (as when pulling doubles or triples ). Some tanks and other tracked vehicles have bogies as external suspension components (see armoured fighting vehicle suspension ). This type of bogie usually has two or more road wheels and some type of sprung suspension to smooth

150-522: A swivel , as traditionally on a railway carriage or locomotive, additionally jointed and sprung (as in the landing gear of an airliner ), or held in place by other means (centreless bogies). Although bogie is the preferred spelling and first-listed variant in various dictionaries, bogey and bogy are also used. A bogie in the UK, or a railroad truck , wheel truck , or simply truck in North America,

180-602: A component of the vast majority of mainline locomotive designs. The first use of bogie coaches in Britain was in 1872 by the Festiniog Railway.The first standard gauge British railway to build coaches with bogies, instead of rigidly mounted axles, was the Midland Railway in 1874. Bogies serve a number of purposes: Usually, two bogies are fitted to each carriage , wagon or locomotive , one at each end. Another configuration

210-438: A retrograde step, as it leads to more wear of both track and wheels and also significantly reduces the speed at which a tram can round a curve. In the past, many different types of bogie (truck) have been used under tramcars (e.g. Brill , Peckham, maximum traction). A maximum traction truck has one driving axle with large wheels and one nondriving axle with smaller wheels. The bogie pivot is located off-centre, so more than half

240-430: A small rail car with axles at either end. The same effect that causes the bogies to rub against the rails at longer radius causes each of the pairs of wheels to rub on the rails and cause the screeching. Articulated bogies add a second pivot point between the two axles ( wheelsets ) to allow them to rotate to the correct angle even in these cases. In trucking , a bogie is the subassembly of axles and wheels that supports

270-413: Is a specialized type of bogie that is inserted under the wheels of a rail wagon/car, usually to convert for another track gauge . Transporter wagons carry the same concept to the level of a flatcar specialized to take other cars as its load. In archbar or diamond frame bogies, the side frames are fabricated rather than cast . Tram bogies are much simpler in design because of their axle load, and

300-464: Is a structure underneath a railway vehicle (wagon, coach or locomotive) to which axles (hence, wheels) are attached through bearings . In Indian English , bogie may also refer to an entire railway carriage . In South Africa , the term bogie is often alternatively used to refer to a freight or goods wagon (shortened from bogie wagon ). A locomotive with a bogie was built by engineer William Chapman in 1812. It hauled itself along by chains and

330-436: Is any one of a number of bogie designs that allow railway equipment to safely turn sharp corners, while reducing or eliminating the "screeching" normally associated with metal wheels rounding a bend in the rails. There are a number of such designs, and the term is also applied to train sets that incorporate articulation in the vehicle, as opposed to the bogies themselves. If one considers a single bogie "up close", it resembles

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360-410: Is often used in articulated vehicles , which places the bogies (often Jacobs bogies ) under the connection between the carriages or wagons. Most bogies have two axles, but some cars designed for heavy loads have more axles per bogie. Heavy-duty cars may have more than two bogies using span bolsters to equalize the load and connect the bogies to the cars. Usually, the train floor is at a level above

390-612: The UIC classification system, which counts axles rather than wheels and uses letters to denote powered axles, the Jervis would be classified 2A. Locomotives without leading trucks are generally regarded as unsuitable for high speed use. The British Railway Inspectorate condemned the practice in 1895, following an accident involving two 0-4-4s at Doublebois , Cornwall, on the Great Western Railway . Other designers, however, persisted with

420-519: The bogie with a centering action. The first use of leading wheels is commonly attributed to John B. Jervis , who employed them in his 1832 design for a locomotive with four leading wheels and two driving wheels (a type that became known as the Jervis ). In the Whyte system of describing locomotive wheel arrangements , his locomotive would be classified as a 4-2-0 , that is to say, it had four leading wheels, two driving wheels , and no trailing wheels . In

450-535: The bogies, but the floor of the car may be lower between bogies, such as for a bilevel rail car to increase interior space while staying within height restrictions , or in easy-access, stepless-entry, low-floor trains. Key components of a bogie include: The connections of the bogie with the rail vehicle allow a certain degree of rotational movement around a vertical axis pivot (bolster), with side bearers preventing excessive movement. More modern, bolsterless bogie designs omit these features, instead taking advantage of

480-591: The individual axles to align with curves in addition to the bogie frame as a whole pivoting. For non-radial bogies, the more axles in the assembly, the more difficulty it has negotiating curves, due to wheel flange to rail friction. For radial bogies, the wheel sets actively steer through curves, thus reducing wear at the wheel's flange-to-rail interface and improving adhesion. In the US, radial steering has been implemented in EMD and GE locomotives. The EMD version, designated HTCR,

510-456: The practice and the famous 0-4-2 Gladstone class passenger expresses of the London, Brighton and South Coast Railway remained in trouble-free service until 1933. A single leading axle (known as a pony truck ) increases stability somewhat, while a four-wheel leading truck is almost essential for high-speed operation. The highest number of leading wheels on a single locomotive is six, as seen on

540-445: The principle of radial steering. The Cleminson system involved three axles, each mounted on a frame that had a central pivot; the central axle could slide transversely. The three axles were connected by linkages that kept them parallel on the straight and moved the end ones radially on a curve, so that all three axles were continually at right angles to the rails. The configuration, invented by British engineer John James Davidge Cleminson,

570-512: The rail. However, if the degree of conicality is inappropriate for the suspension and track, an unpleasant oscillation can occur at high speeds. Recent research is also showing that marginal changes to wheel and rail profiles can improve performance further. Not all railroads have employed conical-tread wheels. The Bay Area Rapid Transit (BART) system in San Francisco , built with cylindrical wheels and flat-topped rails, started to re-profile

600-433: The ride across rough terrain. Bogie suspensions keep much of their components on the outside of the vehicle, saving internal space. Although vulnerable to antitank fire, they can often be repaired or replaced in the field. Wheelset (rail transport) A  wheelset  is a pair of railroad vehicle wheels mounted rigidly on an axle allowing both wheels to rotate together. Wheelsets are often mounted in

630-513: The running wheels, as well. The unusually large flanges on the steel wheels guide the bogie through standard railroad switches , and in addition keep the train from derailing in case the tires deflate . To overcome breaks of gauge some bogies are being fitted with variable gauge axles (VGA) so that they can operate on two different gauges. These include the SUW 2000 system from ZNTK Poznań . Radial-steering trucks, also known as radial bogies, allow

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660-539: The sideways movement of the suspension to permit rotational movement. Modern diesel and electric locomotives are mounted on bogies. Those commonly used in North America include Type A , Blomberg , HT-C and Flexicoil trucks. On a steam locomotive , the leading and trailing wheels may be mounted on bogies like Bissel trucks (also known as pony trucks ). Articulated locomotives (e.g. Fairlie , Garratt or Mallet locomotives) have power bogies similar to those on diesel and electric locomotives. A rollbock

690-471: The tighter curves found on tramways mean tram bogies almost never have more than two axles. Furthermore, some tramways have steeper gradients and vertical as well as horizontal curves, which means tram bogies often need to pivot on the horizontal axis, as well. Some articulated trams have bogies located under articulations, a setup referred to as a Jacobs bogie . Often, low-floor trams are fitted with nonpivoting bogies; many tramway enthusiasts see this as

720-461: The train from derailing if a tyre deflates. The system was originally conceived by Michelin for the Paris Métro ; the first line opened in 1956. Leading wheel Many leading bogies do not have simple rotational motion about a vertical pivot. Bogies with a sliding motion controlled by springs was patented by William Adams in 1865. Other designs used swing links to take the weight of

750-419: The weight rests on the driving axle. The retractable stadium roof on Toronto's Rogers Centre used modified off-the-shelf train bogies on a circular rail. The system was chosen for its proven reliability. Rubber-tyred metro trains use a specialised version of railway bogies. Special flanged steel wheels are behind the rubber-tired running wheels, with additional horizontal guide wheels in front of and behind

780-454: The wheels in 2016 with conical treads after years of complaints about the squeal by its passengers. Australia's Queensland Railways used cylindrical wheels and vertical rails until the mid-1980s, when considerably higher train loads made the practice untenable. Some rubber-tyred metros feature special wheelsets with rubber tyres outside of deep-flanged steel wheels, which guide the bogie through standard railroad switches and keep

810-581: The wheelset to move towards the outer rail on the curve. The cone increases the effective diameter of the wheel as it moves towards the outer rail, and since the wheels are mounted rigidly on the axle, the outer wheels travel slightly farther, causing the wheelsets to more efficiently follow the curve. Abnormal wear at the wheel–rail interface is thus avoided, along with the loud, piercing, very high-pitched squeal which usually results from it – especially evident on curves in tunnels, stations and elevated track, due to flat surfaces slipping and flanges grinding along

840-739: Was first granted a patent in the UK in 1883. The system was widely used on British narrow-gauge rolling stock, such as on the Isle of Man and Manx Northern Railways . The Holdfast Bay Railway Company in South Australia , which later became the Glenelg Railway Company, purchased Cleminson-configured carriages in 1880 from the American Gilbert & Bush Company for its 1600 mm ( 5 ft 3 in ) broad-gauge line. An articulated bogie

870-853: Was made standard equipment for the SD70 series , first sold in 1993. The HTCR in operation had mixed results and relatively high purchase and maintenance costs. EMD subsequently introduced the HTSC truck, essentially the HTCR stripped of radial components. GE introduced their version in 1995 as a buyer option for the AC4400CW and later Evolution Series locomotives. However, it also met with limited acceptance because of its relatively high purchase and maintenance costs, and customers have generally chosen GE Hi-Ad standard trucks for newer and rebuilt locomotives. A 19th century configuration of self-steering axles on rolling stock established

900-540: Was not successful, but Chapman built a more successful locomotive with two gear-driven bogies in 1814. The bogie was first used in America for wagons on the Quincy Granite Railroad in 1829. The first successful locomotive with a bogie to guide the locomotive into curves while also supporting the smokebox was built by John B. Jervis in 1831. The concept took decades before it was widely accepted but eventually became

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