Neoplan Doppelstockbus Viernheim 100 3625

A multi-axle bus is a bus or

coach Coach may refer to: Guidance/instruction * Coach (sport), a director of athletes' training and activities * Coaching, the practice of guiding an individual through a process ** Acting coach, a teacher who trains performers Transportation * Coac ...

that has more than the conventional two

axle An axle or axletree is a central shaft for a rotating 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 the former case, beari ...

s (known as a twin-axle bus), usually three (known as a tri-axle bus), or more rarely, four (known as a quad-axle bus). Extra axles are usually added for legal weight restriction reasons, or to accommodate different vehicle designs such as articulation, or rarely, to implement trailer buses.

History

An early example of a multi-axle bus was a one-off three-axle

Crossley Crossley, based in Manchester, United Kingdom, was a pioneering company in the production of internal combustion engines. Since 1988 it has been part of the Rolls-Royce Power Engineering group. More than 100,000 Crossley oil and gas engines ...

Condor Condor is the common name for two species of New World vultures, each in a monotypic genus. The name derives from the Quechua ''kuntur''. They are the largest flying land birds in the Western Hemisphere. They are: * The Andean condor (''Vu ...

, show
here
built for the 1932 Scottish Bus Show.

Reasons for multiple axles

Usually vehicle licensing authorities of different countries will set legal limits on the amount of weight that can be put on each axle. In the UK, a recent extension to the legal limit on the length of

rigid bus A rigid bus (either a motor bus or trolleybus) is a vehicle used in public transportation services with a single, rigid chassis. A bus of this type is to be contrasted with an articulated or bi-articulated bus, which will have two or more rigid ...

es and coaches has led to the increased use of three axles to accommodate the heavier chassis and passenger load. Certain countries apply exceptions to vehicle rules for specific operations. Extra axles may also be provided on shorter buses and coaches to accommodate extra equipment loads, such as passenger lifts, or comforts such as toilets, televisions, climate controls. In addition, in some cases the need is bus cargo transport, when large cargo compartments and heavy weight of cargo needs extra axles. Adding axles to chassis designs is done for specific reasons such as weight or legalities, as having extra axles means extra costs for the operator in terms of tyre replacement, and to an extent, higher

fuel consumption A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...

Rear axle steering

In some buses the rearmost axle is connected to the

steering Steering is a system of components, linkages, and other parts that allows a driver to control the direction of the vehicle. Introduction The most conventional steering arrangement allows a driver to turn the front wheels of a vehicle using ...

, with the rear most set steering in the opposite direction to the front axle. This steering arrangement makes it possible for the longer triple axle buses to negotiate corners with greater ease than would otherwise be the case.

Rigid chassis

Tri-axle

double-decker bus A double-decker bus or double-deck bus is a bus that has two storeys or decks. They are used for mass transport in the United Kingdom, the United States, New Zealand, Europe, Asia and also in cities such as Sydney; the best-known example is the ...

es are common in high capacity operating environments where articulated buses are not used, such as

Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a List of cities in China, city and Special administrative regions of China, special ...

and

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...

. Tri-axle buses also see high volume use in

Dublin, Ireland Dublin (; , or ) is the capital and largest city of Republic of Ireland, Ireland. On a bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, bordered on the south by the Dublin Mountains, a part of th ...

. Imported tri-axle buses were used initially by

Megabus Megabus may refer to: * Megabus (Europe), a low-cost coach service with services in Europe owned by ComfortDelGro. * Megabus (North America), a low-cost bus service in the United States and Canada owned by Variant Equity Advisors. * Megabús, a ...

for high capacity low cost intercity travel in the UK. Tri-axle double decker coaches have been used to accommodate the extra weight. Models are also being introduced on high capacity inter-city routes, such as by the operator

. A twin steer coach is a rare type of tri-axled coach; where the double axles are in the front and steer, as in the

Bedford VAL The Bedford VAL is a type of coach chassis that was built by Bedford in the United Kingdom from the mid-1960s to the early 1970s. It was unusual at the time for its multi-axle design, in a " chinese six" wheelplan, i.e. with two front steerin ...

or Bustech CDi. The Neoplan Megaliner was the first quad axle double decker coach, and is used in

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...

. Further examples include the Scania K380IB 8x2.

Articulated chassis

Tri-axle is the standard arrangement of two part

articulated bus An articulated bus, also referred to as a banana bus, bendy bus, tandem bus, vestibule bus, wiggle wagon, stretch bus, or an accordion bus, (either a motor bus or trolleybus) is an articulated vehicle used in public transportation. It is u ...

es. Quad-axle arrangement is sometimes employed on articulated buses to accommodate the extra weight of coach bodies, such as in this quad axle articulated coach''
Volvo Articulated Coach
and the quad axle double deck articulated coach, the Neoplan Jumbocruiser. Quad-axle arrangement is also the exclusive arrangement for three part

bi-articulated bus A bi-articulated bus or double-articulated bus and sometimes train-bus or tram-bus is a type of high-capacity articulated bus with an extra axle and a second articulation joint, as well as extended length. Bi-articulated buses tend to be empl ...

es. A rare reason why a bus may have multiple axles is in the case of a trailer bus, where the bus passenger cabin is built as a body

semi-trailer A semi-trailer is a trailer without a front axle. In the United States, the term is also used to refer to the combination of a truck and a semi-trailer; a tractor-trailer. A large proportion of a semi-trailer's weight is supported by a trac ...

towed by a separate

tractor unit A tractor unit (also known as a truck unit, power unit, prime mover, ten-wheeler, semi-tractor, tractor truck, semi-truck, tractor cab, truck cab, tractor rig, truck rig or big rig or simply a tractor, truck, semi or rig) is a characteristical ...

References

External links

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