MufflersRock - Off-Road Mufflers

One of the first modified off-road vehicles was the Kégresse track, a conversion undertaken first by Adolphe Kégresse, who designed the original while working for Tsar Nicholas II of Russia between 1906 and 1916.^[2] 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 World War II a huge surplus of light off-road vehicles like the Jeep and heavier lorries were available on the market.^{[citation needed]} 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, Datsun/Nissan and Mitsubishi. These were all alike; small, compact four wheel drives with at most a small hardtop to protect the occupants from the elements.^{[citation needed]}

From the 1960s more comfortable vehicles were produced.^{[citation needed]} First they were popular for many years with rural buyers due to their off-road and load-lugging capabilities.^{[citation needed]} The U.S. Jeep Wagoneer and the Ford Bronco, the British Range Rover and thestation wagon-bodied Japanese Toyota Land Cruiser and Nissan Patrol were essentially a station wagon body on a light truck frame withfour wheel drive drivetrain. Later during the nineties manufacturers started to add even more luxuries to bring those off-road vehicles on par with regular cars. This eventually evolved into what we call the SUV today, and the newer Crossover vehicle where utility and off-road capability was sacrificed for better on-road handling and luxury.

Technical

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.^{[citation needed]}

Wheeled vehicles accomplish this by having a suitable balance of large or additional tires and tall and flexible suspension.

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 capabilities the tracked drivetrain has the edge.^{[citation needed]}

Most off-road vehicles are fitted with especially low gearing.^{[citation needed]} This allows the operator to make the most of the engine'savailable power, while moving through challenging terrain slowly. 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 driveVolkswagen 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.^[3]

Many wheeled off road vehicles have all wheel drive, to keep traction on slippery surfaces, although in vehicles designed for use both on and off road, this may be switchable so that the vehicle has fewer driven wheels when on the road.

Criticism of off-road vehicles

Safety

SUVs are built with higher ground clearance for off-road use and have a higher center of gravity,^[4] therefore increasing the risk of rollover. Research has shown that whenever an SUV turns, the vehicle's mass resists the turn and carries the weight forward allowing the traction from the tires to create a lateral centripetal force as the vehicle continues through the turn. The conflict between the top weight of the SUV's desire to go straight while the friction of the tires on the road cause the bottom of the vehicle to move away and out from under the vehicle during a turn.^[5]

Pickups and SUVs are more likely to be in rollover accident than passenger cars. According to a study conducted in the United States, pickups have twice the fatality rate of cars and SUVs have nearly triple the fatality rate in rollover accidents.^[6] Of vehicles in the US, light trucks (includes SUVs) represent 36 percent of all registered vehicles. They are involved in about half of the fatal two-vehicle crashes with passenger cars, 80 percent of these fatalities are to occupants of the passenger cars.^[6]

Environment

In the United States, the number of ORV users since 1972 has climbed sevenfold—from five million to 36 million in 2000.^[7] Government policies that protect wilderness but also allow recreational ORV use have been the subject of some debate within the United States and other countries.^[8]

ORVs have also been criticized for producing more pollution in areas that might normally have none. In addition to noise pollution that can cause hearing impairment and stress in wildlife,^[16] according to the U.S. Forest Service, old-style two-stroke engines (no longer a component of new off-road vehicles, although some are still in use) "emit about 20 to 33 percent of the consumed fuel through the exhaust" and "discharge from two-stroke snowmobile engines can lead to indirect pollutant deposition into the top layer of snow and subsequently into the associated surface and ground water."^[17]^[18] In 2002, the United States Environmental Protection Agency‎ adopted emissions standards for all-terrain vehicles that "when fully implemented in 2012... are expected to prevent the release of more than two million tons of air pollution each year -- the equivalent of removing the pollution from more than 32 million cars every year."^[19]^[20]

Common off-road vehicles

Commercial, military and less common off-road vehicles

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.