Co-Bo or Co′Bo′ is a

wheel arrangement In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...

in the

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'', Cre ...

system for railway

locomotive A locomotive or engine is a rail transport vehicle that provides the Power (physics), motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, Motor coach (rail), motor ...

s. It features two uncoupled

bogie A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...

s. The "Co" bogie has three driven axles and the "Bo" bogie has two. The arrangement has been used to even out axle loading. The weight distribution of the locomotive depends on the

power unit In electricity generation, a generator is a device that converts motive power (mechanical energy) or fuel-based power ( chemical energy) into electric power for use in an external circuit. Sources of mechanical energy include steam turbines, g ...

, the engine and generator. If these are not placed symmetrically, the weight distribution is also biased to one end. Placing three axles beneath the engine end and just two beneath the other, with the lighter ancillaries, gives more even loading per-axle.

Examples

Diesel

Leyland railway Metro-Vickers Co-Bo cropped

The

British Railways Class 28 The British Rail Class 28 ( Metro-Vick Type 2) diesel-electric locomotives, known variously as 'Metrovicks', 'Crossleys' or 'Co-Bos', were built under the Pilot Scheme for diesel locomotives as part of the British Railways 1955 Modernisation P ...

is the first (and only) UK locomotive with a Co-Bo wheel arrangement.

C-B

DE10-1081 in Ajikawaguchi IMG 6709 20130811

A similar wheel arrangement, with five axles across two bogies, is also used in Japan for the

Class DE10 The is a class of Japanese C-B wheel arrangement diesel-hydraulic locomotives. 708 locomotives were built between 1966 and 1978. , 138 locomotives remained in operation. Variants DE10-0 subclass 158 DE10-0 locomotives were built with steam ...

, DE11, and DE15 locomotives. As these are

diesel-hydraulic locomotive A diesel locomotive is a type of railway locomotive in which the prime mover is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving wheels ...

s, they are of C-B arrangement, not Co-Bo. A hydrodynamic transmission on the locomotive frame is driven by the

prime mover Prime mover may refer to: Philosophy *Unmoved mover, a concept in Aristotle's writings Engineering * Prime mover (engine), motor, a machine that converts various other forms of energy (chemical, electrical, fluid pressure/flow, etc) into energy o ...

, then drive to each bogie is taken by

cardan shaft A drive shaft, driveshaft, driving shaft, tailshaft ( Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power and torque and rotation, usually used to connect ...

s. The axles of each bogie are all driven, and all geared together, rather than having separate traction motors.

Steam

Some Engerth

steam locomotives A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomot ...

were built to the Fink system, with the four trailing wheels driven by a crankshaft and connecting rods, thus making them

0-6-4-0 Co-Bo or Co′Bo′ is a wheel arrangement in the UIC classification system for railway locomotives. It features two uncoupled bogies. The "Co" bogie has three driven axles and the "Bo" bogie has two. The arrangement has been used to even out axl ...

Ts instead of

0-6-4 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and four trailing wheels on two axles. Overview The 0-6-4 wheel ...

Ts.

In fiction

BoCo is a fictional Co-Bo locomotive, a

British Rail Class 28 The British Rail Class 28 ( Metro-Vick Type 2) diesel-electric locomotives, known variously as 'Metrovicks', 'Crossleys' or 'Co-Bos', were built under the Pilot Scheme for diesel locomotives as part of the British Railways 1955 Modernisation Pl ...

. The locomotive appeared in the

Railway Series ''The Railway Series'' is a series of British books about a railway known as the North Western Railway, located on the fictional Island of Sodor. There are 42 books in the series, the first published in May 1945 by the Rev. Wilbert Awdry. Twe ...

book ''Main Line Engines'' and the following

television series A television show – or simply TV show – is any content produced for viewing on a television set which can be broadcast via over-the-air, satellite television, satellite, or cable television, cable, excluding breaking news, television adverti ...

References

* CB,0C00B0,Co-Bo {{Loco-stub

Examples

Diesel

C-B

Steam

In fiction

See also

References