Off-road vehicle
From Wikipedia, the free encyclopedia
An off-road vehicle is considered to be any type of vehicle which is capable of driving off paved or gravel surface. It is generally characterized by having caterpillar tracks or large tires with deep, open treads and a flexible suspension. Other vehicles that do not travel streets or highways are generally termed off-highway vehicles, which would include things like tractors, forklifts, cranes, backhoes, bulldozers and Golf carts.
Off-road vehicles have an enthusiastic following because of their many uses and versatility. Several types of motorsports involve racing off-road vehicles. The three largest "4 wheel vehicle" off-road types of competitions are Rally, Desert Racing, and Rockcrawling. The three largest types of All Terrain Vehicle (ATV) / Motorcycle competitions are Motocross, Enduro, and Desert Racing. These sports are often celebrated in competition events due to public interest. The most common use of these vehicles is for sight seeing in areas distant from pavement. The use of higher clearance and higher traction vehicles enables access on trails and forest roads that have rough and low traction surfaces.
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[edit] History
One of the first modified off-road vehicles was the Kegresse track, a conversion undertaken first by Adolphe Kégresse, who designed the original while working for Tsar Nicholas II of Russia between 1906 and 1916<ref>MiG-registeret</ref>. The system uses an unusual caterpillar track which uses a flexible belt rather than interlocking metal segments. It can be fitted to a conventional car or truck to turn it into a half-track, suitable for use over rough or soft ground. Conventional front wheels and steering are used.
After the Russian Revolution Kégresse returned to his native France where the system was used on Citroën cars between 1921 and 1937 for off-road and military vehicles. The Citroën company sponsored several overland expeditions with their vehicles crossing North Africa and Central Asia.
After World War II a huge surplus of light off-road vehicles like the Jeep and heavier lorries were available on the market. The Jeeps in particular were popular with buyers who used them as utility vehicles. This was also the start of off-roading as a hobby. The wartime Jeeps soon wore out, though, and the Jeep company started to produce civilian derivatives, closely followed by similar vehicles from British Land Rover and Japanese Toyota and Mitsubishi. These were all alike; small, compact four wheel drives with at most a small hardtop to protect the occupants from the elements.
From the 1960s more comfortable vehicles, later called SUVs, were produced. First they were popular for many years with rural buyers due to their off-road and load-lugging capabilities. The US Jeep Wagoneer and the Ford Bronco, the British Range Rover and the station wagon-bodied Japanese Toyota Land Cruiser were early SUV examples, essentially a station wagon body on a light truck frame with four wheel drive drivetrain.
[edit] Technical
Image:US 5055th Range Squadron M973 SUSV.jpg
To be able to drive off the pavement, off-road vehicles need several characteristics: They need to have a low ground pressure, so not to sink in soft ground, they need ground clearance to not get hung up on obstacles and they need to keep their wheels or tracks on the ground so as to not lose traction.
Wheeled vehicles accomplish this by having a suitable balance of large or additional tires and tall and flexible suspension.
Tracked vehicles accomplish this by having wide tracks and a flexible suspension on the road wheels.
The choice of wheels versus tracks are one of cost and suitability. A tracked drivetrain is more expensive and costly in terms of maintenance. Wheeled drivetrains are cheaper and give a higher top speed. For pure off-road capabilites the tracked drivetrain has the edge.
Most off-road vehicles are fitted with especially low gearing. This allows the operator to make the most of the engine's available power, while moving through challenging terrain at a slow rate of speed. A combustion engine coupled to a normal gearbox often has a too high output speed to be usable. The vehicle often has one of two things; either a very low ("granny") first gear (like the all wheel drive Volkswagen Transporter versions) or an additional gearbox in-line with the first, called a reduction drive. Some vehicles, like the Bv206 in the picture on the right, also has a torque converter to further reduce the gearing <ref>Pakistan Military Consortium</ref>.
[edit] Common off-road vehicles
Common commercial off-road vehicles include four wheel drive pickup trucks like the Chevrolet Silverado, Ford F-Series, GMC Sierra, Toyota Hilux, Dodge Ram and similar. Also common are light trucks with station wagon-like bodies, which have been very popular since the 1980s. These include Chevrolet Blazer, Dodge Ramcharger, Ford Bronco, Jeep Cherokee, Land Rover Defender, Discovery and Range Rover and Toyota's Land Cruiser and 4Runner.
A number of military vehicles have also seen civilian use, including the Jeep CJ and AM General Hummer. Some, like the early Land Rovers, were adapted to military use from civilian specifications.
Specialised commonly available off-road vehicles include ATVs, or All Terrain Vehicles, dirt bikes, dune buggies, rock crawlers and sandrails.
[edit] Commercial, military and less common off-road vehicles
European militaries and utilities have used Haflingers, Pinzgauers and Unimogs for all-terrain transportation. Less common is the Portuguese UMM Alter.
The military market for off-road vehicles used to be large, but since the fall of the Iron Curtain in the 1990s it has to some extent dried up. The U.S. Jeep, developed during World War II, coined the word many people use for any type of light off-road vehicle. In the U.S., the Jeep's successor from the 1980s on was the AM General HMMWV. The Eastern Bloc used the GAZ-69 and UAZ-469 in similar roles.
[edit] Reference
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[edit] See also
eo:Terena aŭtomobilo no:Terrengkjøretøy pl:Samochód terenowy ru:Внедорожник sk:Off-road
