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Abogie (/ˈboʊɡi/BOH-ghee) (ortruck in North American English) comprises two or morewheelsets (twowheels on anaxle), 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 manyrailroad cars andsemi-trailers) or be quickly detachable (as for adolly in aroad train or in railwaybogie exchange). It may includesuspension components within it (as most rail and trucking bogies do), or be solid and in turn be suspended (as are most bogies oftracked vehicles). It may be mounted on aswivel, as traditionally on a railway carriage or locomotive, additionally jointed and sprung (as in thelanding gear of anairliner), or held in place by other means (centreless bogies).[citation needed]
Althoughbogie is the preferred spelling and first-listed variant in various dictionaries,[1][2][3]bogey andbogy are also used.[1][2]
Abogie in the UK, or arailroad truck,wheel truck, or simplytruck in North America, is a structure underneath arailway vehicle (wagon, coach or locomotive) to which axles (hence, wheels) are attached throughbearings. InIndian English,bogie may also refer to an entirerailway carriage.[4] InSouth Africa, the termbogie is often alternatively used to refer to a freight or goods wagon (shortened frombogie wagon).
A locomotive with a bogie was built by engineerWilliam Chapman in 1812. It hauled itself along by chains and was not successful, but Chapman built a more successful locomotive with two gear-driven bogies in 1814.[citation needed] 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 thesmokebox was built byJohn B. Jervis in 1831. The concept took decades before it was widely accepted but eventually became 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 theMidland Railway in 1874.[5]
Bogies serve a number of purposes:[6]
Instability can occur when a combination of bogie design, springing, vehicle and bogie wheelbase, and track dynamics, cause the bogie to oscillate at high speed – a phenomenon known as "hunting". If unchecked, derailment can occur. Cars experiencing hunting are removed immediately once the defect is discovered. A tendency for more than one vehicle to hunt will result in investigations with a view to re-designing.[7]
Usually, two bogies are fitted to eachcarriage, wagon orlocomotive, one at each end. Another configuration is often used inarticulated vehicles, which places the bogies (oftenJacobs bogies) under the connection between the carriages or wagons.
Most bogies have two axles,[6] but some cars designed for superior riding qualities or heavy loads have more axles per bogie. Heavy-duty cars may have more than two bogies usingspan bolsters to equalize the load and connect the bogies to the cars.
Usually, the train floor is at a level above the bogies, but the floor of the area between the bogies may be lowered to increase interior space while staying withinheight restrictions. Examples arecontainer well cars,bi-level passenger cars or stepless-entry, low-floor cars on railways with near-ground-level platforms.
Key components of a bogie include:[6]
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 the sideways movement of the suspension to permit rotational movement.[6]
Moderndiesel andelectric locomotives are mounted on bogies. Those commonly used in North America includeType A,Blomberg, HT-C andFlexicoil trucks.[11]
On asteam locomotive, theleading andtrailing wheels may be mounted on bogies likeBissel trucks (also known aspony trucks).Articulated locomotives (e.g.Fairlie,Garratt orMallet locomotives) havepower bogies similar to those on diesel and electric locomotives.
A rollbock is a specialized type of bogie that is inserted under the wheels of a rail wagon/car, usually to convert for anothertrack gauge. Transporter wagons carry the same concept to the level of aflatcar specialized to take other cars as its load.
In archbar or diamond frame bogies, theside frames arefabricated rather thancast.
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Tram bogies are much simpler in design because of their axle load, and 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.
Somearticulated trams have bogies located under articulations, a setup referred to as aJacobs bogie. Often,low-floor trams are fitted with nonpivoting bogies; manytramway enthusiasts see this as 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.[12]
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 the weight rests on the driving axle.
The retractable stadium roof on Toronto'sRogers 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 the running wheels, as well. The unusually large flanges on the steel wheels guide the bogie through standardrailroad switches, and in addition keep the train fromderailing in case the tiresdeflate.[13]
To overcomebreaks of gauge some bogies are being fitted with variable gauge axles (VGA) so that they can operate on two different gauges. These include theSUW 2000 system fromZNTK Poznań.
Radial-steering trucks, also known as radial bogies, allow 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 towheel flange to rail friction. For radial bogies, the wheel sets actively steer through curves, thus reducing wear at thewheel's flange-to-rail interface and improving adhesion.
In the US, radial steering has been implemented inEMD andGE locomotives. The EMD version, designated HTCR, was made standard equipment for theSD70 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 theAC4400CW and laterEvolution 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 onrolling stock established the principle of radial steering. The Cleminson system[14] 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.[15] The configuration, invented by British engineer John James Davidge Cleminson, was first granted a patent in theUK in 1883.[16] The system was widely used on British narrow-gauge rolling stock, such as on theIsle of Man andManx Northern Railways.[17] TheHoldfast Bay Railway Company inSouth Australia, which later became the Glenelg Railway Company, purchased Cleminson-configured carriages in 1880 from the AmericanGilbert & Bush Company for its1600 mm (5 ft 3 in) broad-gauge line.
Anarticulated bogie (aka Jakob-type) is any one of a number of bogie designs that reduce weight, increase passenger comfort, and allowrailway 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 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 twoaxles (wheelsets) to allow them to rotate to the correct angle even in these cases.
Intrucking, a bogie is the subassembly of axles and wheels that supports asemi-trailer, whether permanently attached to the frame (as on a single trailer) or making up thedolly that can be hitched and unhitched as needed when hitching up a second or third semi-trailer (as whenpulling doubles ortriples).
Sometanks and othertracked vehicles have bogies as external suspension components (seearmoured fighting vehicle suspension). This type of bogie usually has two or more road wheels and some type of sprung suspension to smooth the ride across rough terrain. Bogie suspensions keep much of their components on the outside of the vehicle, saving internal space. Although vulnerable toantitank fire, they can often be repaired or replaced in the field.
