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A three-wheeler is a vehicle with three wheels, either "human or people-powered vehicles" (HPV or PPV or velomobiles) or motorized vehicles in the form of a motorcycle, all-terrain vehicle (ATV) or automobile. Other names for three-wheelers include trikes, tricars and cyclecars. The term tricycle is used somewhat interchangeably, but the term three-wheeler is more often applied to motor vehicles. They can be legally classed as either automobiles or motorcycles.
Many three-wheelers which exist in the form of motorcycle-based machines are often called trikes and often have the front single wheel and mechanics similar to that of a motorcycle and the rear axle similar to that of a car. Often such vehicles are owner-constructed using a portion of a rear-engine, rear-drive Volkswagen Beetle in combination with a motorcycle front end. Other trikes include ATVs that are specially constructed for off road use. Three-wheeled automobiles can have either one wheel at the back and two at the front, (for example: Morgan Motor Company) or one wheel at the front and two at the back (such as the Reliant Robin).
Due to its superior safety when braking, an increasingly popular form is the front-steering "tadpole" or "reverse trike" sometimes with front drive but usually with rear drive. A variant on the 'one at the front' layout was the Scott Sociable, which resembled a four-wheeler with a front wheel missing. Not illustrated is the Thebis rear-steered delta from Sidney, British Columbia
Three-wheeler cars, usually microcars, are often built for economic reasons: in the UK for tax advantages, or in the US to take advantage of lower safety regulations, being classed as motorcycles. As a result of their light construction and potential better streamlining, three-wheeled cars are usually very economical to run.
Three-wheeler transport vehicles known as Auto Rickshaws are a common means of public transportation in many countries in the world. Auto rickshaws are an essential form of urban transport in many developing countries such as India, and a form of novelty transport in many Eastern countries.
In 1897, Edward Butler (inventor) made the Butler Petrol Cycle, another three-wheeled car.
Davis 494, at the National Automotive and Truck Museum, Auburn, IN
Two front 
A configuration of two wheels in the front and one wheel at the back presents two advantages : it has improved aerodynamics, and that it readily enables small lightweight motorcycle powerplant and rear wheel to be used. This approach was used by Messerschmitt kr200 and by the BMW Isetta. Alternatively, a more conventional front-engine, front wheel drive layout as is common in four-wheeled cars can be used, with subsequent advantages for transversal stability (further front location of CG) and traction (two driven wheels instead of one).
For the lowest wind resistance (which increases fuel efficiency), a teardrop shape is desirable. A teardrop is wide and round at the front, tapering at the back. The three-wheel configuration allows the two front wheels to create the wide round surface of the vehicle. The single rear wheel allows the vehicle to taper at the back. This approach is used by the Aptera 2 Series. It is also used by Myers Motors for both its single passenger NmG and upcoming 2-passenger Duo.
Two rear 
Having one wheel in front and two in the rear for power reduces the cost of the steering mechanism, but greatly decreases lateral stability when cornering while braking.
Lateral stability 
The disadvantage of a three-wheel configuration is lateral instability - the car will tip over in a turn before it will slide, unless the centre of mass is much closer to the ground or the track width is much wider than a similar four-wheel vehicle. Electric three-wheelers often lower the center of gravity by placing the heavy battery pack at the base of the vehicle.
Tilting option 
To improve stability some three-wheelers are designed as tilting three-wheelers so that they lean while cornering like a motorcyclist would do. The tilt may be controlled manually or by computer.
A tilting three-wheeler's body and or wheels tilt in the direction of the turn. Such vehicles can corner safely even with a narrow track.
Wheel configurations 
Several configurations are practical. Two front wheels and one rear, where all three wheels tilt, use the acronym 2F3T (i.e. two front three tilt). Other variations include 1F1T, where only the front wheel tilts, an example being the Vandenbrink Carver, made in the Netherlands.
Active or passive tilt control 
Tilting can be actively controlled by applying force between the paired wheels. A "free leaner" is balanced by steering, like a single track vehicle. This still leaves some advantages in traction, and the tilt can be locked for parking faster than a stand can be deployed.
Propulsion may be on one, two, or three wheels, tilted or not. Many possible arrangements require particularly flexible U-joints, which favours the other possibilities.
Use of 'extra' wheel 
Any extra laterally spaced wheel can benefit the vehicle by providing stability gains if there is a mechanism to lock the laterally spaced wheels at any given moment relative to the road plane. In some countersteered vehicles this benefit is generally only available when stopped.
In other types where the tilt angle is directly controlled this additional stability is constant at all speeds.
In a countersteered vehicle a loss of traction will result in a fall whereas in a tilt controlled design a fall may not occur.
Due to the tilting, there is not necessarily any load transfer between the wheels in cornering, so the rule about tadpoles (2F or "reverse trike") understeering and Deltas (1F or standard trike) oversteering does not necessarily apply
In the U.S the National Highway Traffic Safety Administration defines and regulates three-wheeled vehicles as motorcycles. Licensing requirements vary on a state-by-state basis. In other jurisdictions, such as British Columbia, Canada, and Connecticut, a three-wheeled vehicle with an enclosed passenger compartment or partially enclosed seat is considered an automobile.
When the single wheel is in the front (the "delta" form, as in a child's pedal tricycle), the vehicle is inherently unstable in a braking turn, as the combined tipping forces at the center of gravity from turning and braking can rapidly extend beyond the triangle formed by the contact patches of the wheels. This type, if not tipped, also has a greater tendency to spin out ("swap ends") when handled roughly.
With two wheels in the front (the "tadpole" form or "reverse trike") the vehicle is far more stable in braking turns, but remains more prone to overturning in normal turns compared to an equivalent four-wheeled vehicle, unless the center of mass is lower and/or further forward. Motorcycle-derived designs suffer from most of the weight being towards the rear of the vehicle.
Due to the incidence of injuries related to their use, a 10-year ban was placed on the sale of new three-wheeled ATVs in the United States in January 1988.
In popular culture 
In the British TV series Mr. Bean, a Reliant Regal three-wheeler was often driving around town. The car was sort of a nemesis to Mr. Bean, as he would drive in such a manner as to cause the car to roll over and even refused a ride from the three-wheeler when hitchhiking.
|Léon Bollée Voiturette||France||1895-?|
|Advance 6 hp air-cooled Tri Car and 9 hp water-cooled Tri Car||England||1902-12|
|Riley Olympia Tricar||England||1904|||
|Lagonda Tricar||England||1904-07||total production: 69 cars|
|Morgan V-Twin and F-Series||England||1911-39, 1932–52||Morgan Super Sports 2-Seater 1937|
|American Tri-Car||United States||1912|
|Birmingham Small Arms Company Three Wheeler||England||1929-36||1100cc engine|
|Zaschka||Germany||1929||Folding three-wheeler: Zaschka Three-wheeler 1929|
|Dymaxion car||United States||1933||Concept car designed by Buckminster Fuller|
|Mathis VEL 333||France||1946||3 seats, flat-twin front engine, aluminium body, production less than 10 units|
|Velorex Oskar and other models||Czechoslovakia||1951-71||Originally with leather bodies|
|Isetta||UK||1957-62||Three-wheeled version of the Isetta built in the UK to take advantage of tax and licencing regulations|
|Peel P50||Isle of Man||1963-64||Smallest production car ever built|
|HM Vehicles Free-way||United States||1979-82|
|Campagna T-Rex||Canada||1996–present||Most likely the fastest (157 mph) most expensive ($50k MSRP) production 3-wheeler|
|Malone Car Company F1000|Skunk SS|TAZR||United Kingdom||1999–present||High power internal combustion and pure electric versions released November 2010|
|Cree SAM||Switzerland||2001||Electric, only 80 produced|
|ScootCoupe||United States||2004–present||Smallest production car currently, requiring no license to operate due to its moped drive-train|
|Myers Motors NmG ("No more Gas")||United States||2006–present||Single occupant all-electric plug-in: 75 mph, 50-60 mile range, lithium batteries. Developed from Corbin Sparrow. The 2-passenger model, the Duo, is scheduled for release in 2010.|
|Moonbeam||United States||2008–present||100 mpg DIY, fabric-covered car based on parts from two Honda 150cc motorscooters|
|Triac||United States||2009-2011||Electric, never entered production|
|XR-3 Hybrid||United States||Plans-2008, Kit-2009||Front 3 cylinder diesel (125 mpg), rear electric 40 mile range -(220 mpg when used as a hybrid)|
|Aptera 2e||United States||Electric or Plug-in hybrid, 300 mpg-US (0.78 L/100 km)|
|Benz Patent Motorwagen||Germany||1886-93|
|La Va Bon Train||France||1904-10||50-100 believed built|
|Davis D-2 Divan||United States||1947-48||about 13-17 built, including the 494, a Jeep-like military vehicle|
|Kia K-360||Republic of Korea||1962-1973||356 cc, 11 hp, air-cooled two cylinder. Top speed 65 km/h and a maximum load of 300 kg. This was Kia's first truck. The spare wheel was located on the roof.|
|Kia T-1500||Republic of Korea||1963-?||1484 cc, 60 hp, four cylinder and a maximum load of 1.5 tons.|
|Kia T-600||Republic of Korea||1969-1974||577cc, 20 HP and 500 kg load. Top speed of 75 km/h. 7726 produced.|
|Kia T-2000||Republic of Korea||1967-1981||1985 cc, 81 hp, four cylinder and a maximum load of 2 tons. 15952 produced.|
|Electra-King||United States||1964?-1980s?||Two-seater electric car manufactured by B & Z Electric Car Company|
|Reliant Robin||England||1973-81, 1989-2002|
|GM Lean Machine||United States||1980s||Tilt, concept car only, conceived by Frank Winchell|
|elio motors||United States||2014|
|ZAP Xebra||United States||2006-2009||electric power|
|Snyder ST600-C||United States||20??-20??|
See also 
- Auto rickshaw
- Bubble car
- Cabin cycle
- Corbin Sparrow
- Davis Motorcar Company
- Egy-Tech Engineering
- Electric trike
- Feet forwards motorcycle
- Goliath (car)
- Harley-Davidson Servi-Car
- Motorized tricycle (Philippines)
- Myers Motors NmG
- Piaggio MP3
- Steam tricycle
- T-Rex (automobile)
- Volkswagen 1-litre car
- Volkswagen GX3
- "Scott Sociable". Retrieved 2010-03-27.
- Elvis Payne (2012). "The History of the 3-Wheeled Vehicle". 3-wheelers.com. Retrieved 2012-01-03.
- Chris Chong (July 2, 2006). "History in its magnificence". star-motoring.com. Archived from the original on 2007-10-24. Retrieved 2008-01-20.
- "History". pekingparisraid.co.uk. Archived from the original on 2007-08-26. Retrieved 2008-01-20.
- "Related Highway Safety Provisions".
- "3-wheelers on TV 2.". 3-wheelers.com. Retrieved 26 December 2011.
- "Advance Fore-Cars and Tri-Cars". oakingtonplane.co.uk. Archived from the original on 2008-01-12. Retrieved 2008-01-23.
- "British Motor Manufacturers (1894-1960) Humber". britishmm.co.uk. Retrieved 2008-01-20.
- "Humber History". histomobile.com. Retrieved 2008-01-20.[dead link]
- "Rileys 1896 - 1939 The Pre-Nuffield Years.". Rob's Riley Pages (ukonline.co.uk/rileyrob). Retrieved 2008-01-20.
- illustration[dead link]
- "The History of Classic Cars: 1905 Lagonda Tricar". autoclassic.com. Retrieved 2008-01-20.
- Peter Bowler, president The BSAFWD Club. "image and description". Bsafwdc.co.uk. Retrieved 2012-04-09.
- – Mark Wilson (2006-09-24). "Moonbeam: 100mpg Homemade Car". Gizmodo.com. Retrieved 2012-04-09.
- "XR3 Hybrid Personal Transit Vehicle: A 125 mpg Plug-In Hybrid Three Wheeler You Build From Plans". Rqriley.com. Retrieved 2012-04-09.
- Phil Patton, "A Dreamer's Machine, More Promise Than Reality", New York Times (September 24, 2009)
- Rob & Sharon McLellan. "advertising brochure". Mclellansautomotive.com. Retrieved 2012-04-09.
- "General Motors Three Wheeled Cars.". GM's Lean Machine (3-wheelers.com/gmlean). Retrieved 2008-04-08.
- "Lean Machines: Preliminary Investigation.". Institute of Transportation Studies, University of California at Berkeley (commutercars.com/downloads/studies/). Retrieved 2008-04-08.[dead link]
- "illustration". Retrieved 2012-04-09.
- "elio motors". Retrieved 2013-04-16.
- http://www.eliomotors.com. Missing or empty
||This article's use of external links may not follow Wikipedia's policies or guidelines. (August 2010)|
- All about 3-wheeled ATVs
- Online A-Z of 3-wheeled cars
- Article on three-wheeled ATV safety at The American Academy of Pediatrics
- Gallery of Japan three-wheelers
- Theory and Practice of Three Wheel design (English & Français)
- Photo catalog of past and present three-wheel motor vehicles (street driven)
- "Three Wheel Cars; Primary Factors that Determine Handling & Rollover Characteristics" at Robert Q. Riley's website
- History of the Three Wheeler
- Link index for three-wheeled cars as well as other types