A Bo-Bo-Bo or Bo′Bo′Bo′ (

UIC classification The UIC classification of locomotive axle arrangements, sometimes known as the German classification''The Railway Data File''. Leicester: Silverdale, 2000. p. 52. . or German system,Kalla-Bishop P.M. & Greggio, Luciano, ''Steam Locomotives'', Cr ...

) is a

locomotive A locomotive is a rail transport, rail vehicle that provides the motive power for a train. Traditionally, locomotives pulled trains from the front. However, Push–pull train, push–pull operation has become common, and in the pursuit for ...

with three independent two-axle

bogies A bogie ( ) (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 ...

with all

axle An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In ...

s powered by separate

traction motor A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric vehicle, electric or hydrogen vehicles, or electric multiple unit trains. Traction (engineering), Traction motors are used in electrically powe ...

s. In the AAR system, this is simplified to B-B-B due to the system only taking powered axles into consideration, not traction axles. The Bo-Bo-Bo configuration is often used to lower axle weight while keeping lateral forces low compared to a locomotive with two three-axle bogies, thus allowing the locomotive to use lightly laid track, in particular

narrow-gauge railways A narrow-gauge railway (narrow-gauge railroad in the US) is a railway with a track gauge (distance between the rails) narrower than . Most narrow-gauge railways are between and . Since narrow-gauge railways are usually built with Minimum railw ...

Bo-Bo-Bo locomotives

The arrangement is extensively used on

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

and

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

ese railways. Other examples include

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

's DJ, EW and EF classes; the Eurotunnel Class 9 locomotives, which were themselves derived from the New Zealand EF class; the Swiss

SBB SBB may refer to: Arts and entertainment * SBB (band), a Polish progressive rock band, or their self-titled albums: ** ''SBB'' (1974 album) ** ''SBB'' (1978 album, Amiga) * Seán Bán Breathnach, also known as SBB, Irish TV personality * ''Saa ...

Re 6/6 The Re 620, Re 6/6 in the old numbering scheme, are six-axle, electric locomotives of Swiss Federal Railways (SBB CFF FFS), which were acquired as a replacement for the Ae 6/6 for heavy services on the Gotthard Railway. They were produced betwe ...

(Re 620); the Russia Railways VL65, EP1 (EP1M), EP10 and

EP20 An extended play (EP) is a musical recording that contains more tracks than a single but fewer than an album. Contemporary EPs generally contain up to eight tracks and have a playing time of 15 to 30 minutes. An EP is usually less cohesive ...

; and the

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

Korail Class 8000 The Korail Class 8000 locomotive is a series of South Korean electric locomotives operated by Korail. This locomotive was introduced from 1972 to 1990, after electrification of several industrial lines. It was assigned both passenger and freig ...

. China imported 6K

electric locomotive An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a Battery (electricity), battery or a supercapacitor. Locomotives with on-board fuelled prime mover (locomotive), ...

from Japan between 1986 and 1987. The Bo-Bo-Bo design was applied to SS7 series except SS7E. Locomotives of this type are also used on

Myanmar railways Rail transport in Myanmar consists of a railway network with 960 stations. The network, generally spanning north to south with branch lines to the east and west, is the second largest in Southeast Asia, and includes the Yangon Circular Railway ...

. The

State Rail Authority The State Rail Authority, a former statutory authority of the Government of New South Wales, operated and maintained railways in the Australian state of New South Wales from July 1980 until December 2003. History The ''Transport Authorities A ...

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

built the last of its 86 Class electric locomotives (8650) in the Bo-Bo-Bo arrangement (called locally a Tri-Bo), but this did not prove successful and it spent long periods out of traffic undergoing repair. The first Italian six-axle electric locomotives, such as the E.626, used a Bo′BoBo′ layout, where the two centre axles were mounted on a

rigid frame Rigid or rigidity may refer to: Mathematics and physics *Stiffness, the property of a solid body to resist deformation, which is sometimes referred to as rigidity *Structural rigidity, a mathematical theory of the stiffness of ensembles of rig ...

and only the outer pairs on bogies. This wheel arrangement requires either an articulated frame (becoming a Bo+Bo+Bo arrangement) or else significant side play on the center bogie. The Italian locomotives and New Zealand EW class are articulated, whereas the Eurotunnel and New Zealand EF and DJ class locomotives' central bogies have a lot of sideplay.

B′B′B′ locomotives

A similar arrangement, but without separate traction motors for each axle, would be a B′B′B′ arrangement as UIC, indistinguishably B-B-B in AAR. This arrangement has been used for electric locos with three monomotor bogies, such as the Italian FS Class E.632 of 1982.

Bo′Bo′Bo′+Bo′Bo′Bo′ locomotives

These are a pair of Bo′Bo′Bo′ locomotives semi-permanently coupled as a single unit. They are each constructed with a single cab, giving a cab at each end. This layout includes Russian freight electric locomotives VL15,

VL85 The VL85 () is a Soviet Union, Soviet (and later Russian) built electric mainline freight locomotive manufactured at the Novocherkassk Electric Locomotive Plant (NEVZ) and designed under the management of V.Ya.Sverdlov (ru:В.Я.Свердлов) ...

, VL86f and the experimental gas turbine electric locomotive GT1h-001, which was converted from an electric locomotive VL15.

References

{{Locostyles Locomotives by wheel arrangement

Bo-Bo-Bo locomotives

B′B′B′ locomotives

Bo′Bo′Bo′+Bo′Bo′Bo′ locomotives

See also

References