A monomotor bogie () is a form of traction

bogie A bogie ( ) (or truck in North American English) comprises two or more Wheelset (rail transport), wheelsets (two Railroad wheel, wheels on an axle), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes ...

used for an

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), ...

diesel-electric locomotive A diesel locomotive is a type of railway locomotive in which the power source 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 whee ...

. It is distinguished by having a single

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 ...

on each bogie.

Development

The first electric locomotives used large diameter

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

s, mounted rigidly on their

frame A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (con ...

s and using jackshaft drives and

coupling rod A coupling rod or side rod connects the driving wheels of a locomotive. Steam locomotives in particular usually have them, but some diesel and electric locomotives, especially older ones and shunter locomotives, also have them. The coupling ro ...

s to carry their torque to the

driving wheel On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled t ...

s. This increased their

unsprung weight The unsprung mass (colloquially unsprung weight) of a vehicle is the mass of the suspension, wheels or tracks (as applicable), and other components directly connected to them. This contrasts with the sprung mass (or weight) supported by the ...

and limited their maximum speed, despite the greater power of electric locomotives.

Leading trucks

To achieve a higher speed, locomotives began using wheel arrangements such as 2'Do2' (AAR: 2-Do-2), with the SNCF Class 2D2 5500 This used leading (and trailing)

pony truck A Bissell or Bissel truck (also Bissel bogie or pony truck) is a single-axle bogie which pivots towards the centre of a steam locomotive to enable it to negotiate curves more easily. Invented in 1857 by and usually then known as a ''pony truck'' ...

s or

s to provide stability at high speed, with individual

s for each axle, avoiding the weight of the coupling rods. Suspension travel for each axle was achieved with a

Buchli drive The Buchli drive is a transmission system used in electric locomotives. It was named after its inventor, Swiss engineer Jakob Buchli. The drive is a fully spring-loaded Vehicle propulsion, drive, in which each floating axle has an individual moto ...

on each axle. Unlike the original Swiss practice with a Buchli drive on one end of the axle, the French locomotives used a double-ended drive. This was later given as a reason for the low wear rates experienced with them. These locomotives first appeared during the 1930s with the 2D2 5500, and later during the post-war push for

electrification Electrification is the process of powering by electricity and, in many contexts, the introduction of such power by changing over from an earlier power source. In the context of history of technology and economic development, electrification refe ...

the SNCF Class 2D2 9100 (1950).

Bogies

Shortly after the 9100 class, the French absorbed another new Swiss idea, that of the high-speed double-bogie locomotive. Previous French Bo-Bo locomotives had been considered suitable only for medium speeds, with the pony truck and rigid frame used for express passenger service. The Swiss Re 4/4^I of 1946 achieved speeds of up to , owing to the advanced design of its bogies. New classes were built for French railways, embodying these principles. Two 1,500 V DC prototype Co-Co locomotives for the

SNCF Class CC 7100 SNCF's CC 7100 class are part of a series of electric locomotives built by Alstom. The prototype 'CC 7000' (7001 & 7002) were built in 1949 and the production series locomotives CC 7101-CC 7158 followed during 1952–1955. Two of the class are no ...

(1952) were built by

Alsthom Alstom SA () is a French multinational rolling stock manufacturer which operates worldwide in rail transport markets. It is active in the fields of passenger transportation, signaling, and locomotives, producing high-speed, suburban, regional a ...

, the first prototypes being tested from 1949. These locomotives had conventional per-axle traction motors. During tests in 1954 they achieved extremely high test speeds of , which have not yet been surpassed by locomotive-hauled trains.

Monomotor bogies

SNCF Class BB 16500 (1962) SNCF Class BB 7200 (1967) This was the first of the '

Nez Cassé The Nez Cassé series of locomotives is a large family of electric and diesel locomotives intended primarily for fast passenger service on the French SNCF railway system. Produced by Alstom, Alsthom for use under multiple electrification networks ...

' designs, by

Paul Arzens Paul Arzens (28 August 1903 – 2 February 1990) was a French industrial designer of railway locomotives and motor cars. Arzens was born in Paris, at an address along the on the northern side of the city. As a young man he studied at t ...

Class CC 40100 (1964), a large quad-voltage locomotive, requiring a C'C' layout with three axle bogies.

Use

Monomotor bogies are widely used in France, for designs by

Alstom Alstom SA () is a French multinational rolling stock manufacturer which operates worldwide in rail transport markets. It is active in the fields of passenger transportation, signaling, and locomotives, producing high-speed, suburban, regional ...

. They were a particular feature of the '

' family of locomotives, designed by

Examples

* SNCF Class BB 7200 DC * SNCF Class BB 15000 AC * SNCF Class BB 22200 Dual-voltage, combining the attributes of both BB 7200 and BB 15000 (7200 + 15000 = 22200) * SNCF Class BB 26000 * NS Class 1600 Dutch version of the SNCF Class BB 7200 * FS Class E.632 (Italian)

References

Bibliography

* {{SNCF locos Locomotive parts