Three-wheeler

A photograph of the Benz Patent Motorwagen

Diagram demonstrating the wheel positions for various three-wheeled car configurations when turning

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 handling superiority, 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.

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 often relaxed pollution requirements, leading to higher efficiency, three-wheeled cars are usually very economical to run.

History

Early car pioneer Karl Benz developed a number of three-wheeled models. One of these, the Benz Patent Motorwagen, is widely regarded as the first purpose-built automobile. It was built in 1885.

In 1896, John Henry Knight showed a tri-car at The Great Exhibition.

In 1897, Edward Butler (inventor) made the Butler Petrol Cycle, another three-wheeled car.

A Conti 6 hp Tri-car competed in (but did not complete) a 1907 Peking-to-Paris race sponsored by a French newspaper, Le Matin.

Configurations

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.^{[citation needed]} 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 wheelbase 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

A Honda Canopy used for delivery service

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

With bicycles and motor bikes without enclosure, passive tilt control is possible. The rider is responsible for holding the balance.

Topology

Propulsion may be on the tilted wheels also with so called tadpoles but requires special controllers when having propulsion on two tilted wheels.

Use of 'extra' wheel

Tripendo recumbent tricycle, a tilting three-wheeler

Vandenbrink Carver

 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 will not occur.

Various electric and hydraulic systems have been employed to modify TTW behaviour, with notable success on the Carver.

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

Registration

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.

Safety

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.

1932 Morgan Aero 2-Seater Sports

In popular culture

One of the most famous three-wheeled cars is the dirty yellow Reliant Regal Supervan III from the TV series Only Fools and Horses.

In the TV series Mr. Bean, a Reliant Regal (a 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.

Examples

Two front wheels

Name	Country	Years manufactured	Wheel configuration	Comments
Léon Bollée Voiturette	France	1895-?	2 front
Egg	Switzerland	1896-99
Advance 6 hp air-cooled Tri Car and 9 hp water-cooled Tri Car	England	1902-12	2 front
Humber Tricar	England	1904	2 front
Riley Olympia Tricar	England	1904	2 front
Lagonda Tricar	England	1904-07	2 front	total production: 69 cars
Anglian	England	1905-07
Armadale	England	1906-07
Morgan V-Twin and F-Series	England	1911-39, 1932-52	2 front	Morgan Super Sports 2-Seater 1937
American Tri-Car	United States	1912
Birmingham Small Arms Company Three Wheeler	England	1929-36	2 front	1100cc engine
Zaschka	Germany	1929	2 front	Folding three-wheeler: Zaschka Three-wheeler 1929
Dymaxion car	United States	1933	2 front	Concept car designed by Buckminster Fuller
Mathis VEL 333	France	1946	2 front	3 seats, flat-twin front engine, aluminium body, production less than 10 units
Velorex Oskar and other models	Czechoslovakia	1951-71	2 front	Originally with leather bodies
Iso Isetta	Italy	1953	2 front
Messerschmitt KR175	Germany	1953-55	2 front
Messerschmitt KR200	Germany	1955-64	2 front
Peel P50	Isle of Man	1963-64	2 front	Smallest production car ever built
HMV Freeway	United States	1979-82	2 front
Campagna T-Rex	Canada	1996-present	2 front	Most likely the fastest (157 mph) most expensive ($50k MSRP) production 3-wheeler
Malone Car Company Skunk SS|TAZR	United Kingdom	1999-present	2 front	High power internal combustion and pure electric versions released November 2010
Cree SAM	Switzerland	2001	2 front	Electric, only 80 produced
ScootCoupe	United States	2004-	2 front	Smallest production car currently, requiring no license to operate due to its moped drive-train
Myers Motors NmG ("No more Gas")	United States	2006-	2 front	Single occupant all-electric plug-in: 75mph, 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-	2 front	100mpg DIY, fabric-covered car based on parts from 2 Honda 150cc motorscooters
Triac	United States	2009-2011	2 front	Electric, never entered production
XR-3 Hybrid	United States	Plans-2008, Kit-2009	2 front	Front 3 cylinder diesel (125 mpg), rear electric 40 mile range -(220 mpg when used as a hybrid)
Aptera 2e	United States		2 front	Electric or Plug-in hybrid, 300 mpg-US (0.78 L/100 km)

Two rear wheels

Name	Country	Years manufactured	Wheel configuration	Comments
Benz Patent Motorwagen	Germany	1886-93	2 rear
La Va Bon Train	France	1904-10	2 rear	50-100 believed built
Autoette	United States	1948-70	2 rear
Scammell Scarab	England	1948-67	2 rear
Daihatsu Bee	Japan	1951-?	2 rear
Daihatsu Midget	Japan	1957-72	2 rear
Mazda T-2000	Japan	1957-74	2 rear
Mazda K360	Japan	1959-69	2 rear
Mazda T600	Japan	1959-71	2 rear
Electra-King	United States	1964?-1980s?	2 rear	Two-seater electric car manufactured by B & Z Electric Car Company
Bond 875	England	1965-70	2 rear
Reliant Robin	England	1973-81, 1989-2002	2 rear
GM Lean Machine	United States	1980s	2 rear	Tilt, concept car only, conceived by Frank Winchell
Twike	Germany	1995-present	2 rear	Human-electric hybrid
ZAP Xebra	United States	2006-2009	2 rear	electric power
Carver	Netherlands	2007-2009	2 rear	Tilt

See also

• Auto rickshaw
• Bubble car
• Cabin cycle
• CityEl
• CLEVER
• Corbin Sparrow
• Cushman
• 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)
• Tri-Magnum
• Tuk-tuk
• Volkswagen 1-litre car
• Volkswagen GX3

External links

• All about 3-wheeled ATVs
• Online A-Z of 3-wheeled cars
• Article on three-wheeled ATV safety from 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
• "Three Wheel Cars; Primary Factors that Determine Handling & Rollover Characteristics"
• Link index for three-wheeled cars as well as other types