A snowmobile is a land vehicle that is commonly propelled by a continuous track or tracks at the rear and steered by skis at the front. It can also be known in some places as a snowmachine, snowsled or the genericized trademark of the Bombardier product, Ski-Doo.
Early snowmobiles used rubber tracks, however modern snowmobiles typically have tracks made of a Kevlar composite. They are designed to be operated on snow and ice, and require no road or trail. Originally snowmobiles were typically powered by two-stroke gasoline/petrol internal combustion engines. Four-stroke engines are becoming more and more popular in snowmobiles. Noise and air pollution concerns and regulations are a driving factor in this transition. Summertime occupations for snowmobile enthusiasts can also involve drag racing on grass, asphalt strips, or even across water.
People who ride them commonly are known as snowmobilers. The main types of riding are Snowcross/racing, trail riding, x games, and mountain climbing.
History Multi-passenger snowmobiles Main articles: Aerosan and Snowcat The NKL-26 armoured Aerosan of World War Two. Nicholas II Delaunay-Belleville with Kégresse track
The origin of the snowmobile is not the work of any one inventor but more a process of advances in engines for the propulsion of vehicles and supporting devices over snow. It parallels the development of the automobile and later aviation, often inventors using the same components for a different use.
The Aerosan, propeller-powered and running on skis, was built in 1909-1910 by the Russian inventor Igor Sikorsky. Aerosans were used by the Soviet Red Army during the Winter War and the Second World War There is some dispute over whether Aerosans should be considered snowmobiles, as they are not propelled by tracks, but if they are, they would be the first snowmobiles developed.
Adolphe Kégresse designed an original caterpillar tracks system, called the Kégresse track, while working for Tsar Nicholas II of Russia between 1906 and 1916. These used a flexible belt rather than interlocking metal segments and could be fitted to a conventional car or truck to turn it into a half-track, suitable for use over soft ground, including snow. Conventional front wheels and steering were used but the wheel could be fitted with skis as seen in the upper right image. He applied it to several cars in the Royal garage including Rolls-Royce cars and Packard trucks. Although this was not a snowmobile, it could be thought as one of the ancestor of the modern concept.
The first United States patent for a snow-vehicle using the now recognized format of rear track(s) and front skis was issued to Ray H. Muscott of Waters, MI on June 27, 1916 with U.S. Patent # 1,188,981. Many individuals later modified Ford Model Ts with the undercarriage replaced with tracks and skis following this design. They were popular for rural mail delivery for a time.Early Bombardier Snowmobile Early snowmobile interior
The relatively dry snow conditions of the United States Midwest suited the converted model Ts and other like vehicles but they were not suitable for operation in more humid snow areas such as Southern Quebec. This led Joseph-Armand Bombardier of the small town of Valcourt in Quebec, Canada, to invent a different caterpillar track system suitable for all kinds of snow conditions. Bombardier had already made some "metal" tracked vehicles since 1928, but his new revolutionary track traction system (a toothed wheel covered in rubber, and a rubber and cotton track that wraps around the back wheels) was his first major invention. He started production of a large, enclosed, seven-passenger snowmobile in 1937, the B-7 and introduced another enclosed twelve-passenger model, the B-12 in 1942. The B-7 had a V-8 flathead engine from Ford Motor Company. The B-12 had a flathead in line six cylinder engine from Chrysler industrial, and 2,817 units were produced until 1951. It was used in many applications, such as ambulances, Canada Post vehicles, winter "school buses", forestry machines and even army vehicles in World War II. Bombardier had always dreamed of a smaller version, more like the size of a motor scooter. Individual snowmobiles A snowmobile used by emergency services in ski areas in Vercors, French Alps. It carries emergency equipment and tows a stretcher.
Numerous people had ideas for a smaller personal snowmobile. In 1914, O.M. Erickson and Art Olsen of the P.N. Bushnell company in Aberdeen, South Dakota built an open two-seater "motor-bob" out of an Indian motorcycle modified with a cowl-cover, side by side seating, and a set of sled-runners fore and aft. While it did not have the tracks of a true snowmobile, its appearance was otherwise similar to the modern version and is one of the earliest examples of a personal motorized snow-vehicle. Edgar and Allen Hetteen and David Johnson of Roseau, Minnesota were among the first to build a practical snowmobile in 1955–1956, but the early machines were heavy (1,000 lb/450 kg) and slow (20 mph/32 km/h). Their company, Hetteen Hoist & Derrick Co., became Polaris Industries, a major snowmobile manufacturer.. It was only in 1959, when engines became lighter and smaller than before, that Bombardier invented what we know as the modern snowmobile in its open-cockpit one- or two-person form, and started selling it as the "Ski-doo". Competitors sprang up and copied and improved his design.
In the 1970s there were over a hundred snowmobile manufacturers. From 1970 to 1973 they sold close to two million machines, a sales summit never since equalled, with a peak of half a million in 1971. Many of the snowmobile companies were small outfits and the biggest manufacturers were often attempts by motorcycle makers and outboard motor makers to branch off in a new market. Most of these companies went bankrupt during the gasoline crisis of 1973 and succeeding recessions, or were bought up by the larger ones. Sales rebounded to 260,000 in 1997 but went down gradually afterward, influenced by warmer winters and the use during all four seasons of small one- or two-person ATVs. The snowmobile market is now divided up between the four large North American makers (BRP or Bombardier Recreational Products, Arctic Cat, Yamaha, and Polaris) and some specialized makers like the Quebec-based AD Boivin (manufacturer of the Snow Hawk) and the European Alpina Snowmobiles.
Some of the higher powered modern snowmobiles can achieve speeds in excess of 120 mph (190 km/h). Drag racing snowmobiles can reach speeds in excess of 180 mph (290 km/h).a dual track snowmobile
Snowmobiles are widely used in arctic territories for travel. However, the small population of the Arctic areas makes for a correspondingly small market. Most of the annual snowmobile production is sold for recreational purposes much further south, in those parts of North America where the snow cover is stable during the winter months. The number of snowmobiles in Europe and other parts of the world is relatively low, though they are growing rapidly in popularity.
Snowmobiles designed to perform various work tasks have been available for many years with dual tracks from such manufacturers as Aktiv (Sweden), who made the Grizzly, Ockelbo (Sweden), who made the 8000, and Bombardier who made the Alpine and later the Alpine II. Currently Alpina Snowmobiles is the only manufacturer of dual track work sleds.
An odd version of snowmobile is the Swedish Larven made by Lenko in Östersund from the 1960s until the end of the 1980s. It was a very small and basic design with just an engine in the rear and a track. The driver sat on it and steered using skiis on his feet Performance
Snowmobiles are capable of moving across steep hillsides without sliding downslope as the rider is putting his weight toward the uphill side. High-performance snowmobiles will beat most stock or aftermarket cars in a 0-100 km/h drag race (when the snowmobile is equipped for "asphalt drags"). Many 2007 snowmobiles will accelerate to 100mph+ in under six seconds(when set-up for ice-drags). Mountain sleds permit access in remote areas, of deep snow, which was nearly impossible a few decades ago. This is mainly due to improvements in technology.
Cornices and other kinds of jumps are sought after for aerial maneuvers. Riders often search for un-tracked, virgin terrain and are known to "trailblaze" or "boondock" deep into remote territory where there is absolutely no visible path to follow. However, this type of trailblazing is not without hazards: Contact with buried rocks, logs and even frozen ground, can cause extensive damage to snowmobiles (and/or injuries to the rider). Riders will often look for large open fields of fresh snow where they can carve. Some riders use extensively modified snowmobiles, customized with aftermarket accessories such as handle bar risers, handguards, custom/lightweight hoods, windshields, and seats, running board supports, and numerous other modifications that increase power and maneuverability. Many of these customizations can now be purchased straight off the showroom floor on stock models. Environmental impact
The environmental impact of snowmobiles has been the subject of much debate. Governments have been reacting slowly to noise and air pollution, partly due to lobbying from manufacturers and users of snowmobiles. For instance, in 1999, the Canadian government adopted the Canadian Environmental Protection Act, but the set of rules governing pollution emissions for off-road vehicles was only released in January 2005. . Another example of regulation, only four-stroke snowmobiles are allowed in Yellowstone National Park since a bylaw was recently passed to minimize CO2 emissions and noise.. In Yellowstone, snowmobiles account for 80% of total hydrocarbons emissions and 50% of carbon monoxides emissions.
Maximum noise restrictions have been imposed by law for both production snowmobiles and aftermarket components. Efforts towards noise reduction have been so successful that engineers no longer look to engine noise as the major source of snowmobile noise and have moved on to suppressing mechanical noise caused by the suspension components and tracks. Ski-doo has introduced silent track technology to some production models. Air
Most snowmobiles are still powered by two-stroke engines, although Alpina Snowmobiles and Yamaha have been using four-strokes respectively since 2002 and 2003. However, in the last decade several manufacturers have been successful in designing less polluting motors, and putting most of them in production. Yamaha and Arctic-Cat were the first to mass produce four-stroke models, which are significantly less polluting than the early two-stroke machines. Alpina offers a 4-stroke EFI engine equipped with a catalytic converter and state of the art dual oxygen-probe. Bombardier's Semi-Direct Injection (SDI) two-stroke motors emit 60 percent less pollutants than previous carburated 2-strokes. Polaris has developed a fuel-injection technology called "Cleanfire Injection" on their 2 strokes. The industry is also working on direct injected "clean two strokes" which are actually an improvement on carbureted four strokes in terms of NOX emissions.
Independent researchers are also working on the air pollution issue. Even undergraduate and graduate students are participating in contests to lessen the impact of emissions from snowmobiles. The Clean Snow Mobile Challenge is held yearly at Michigan Tech University regrouping the entries from universities from across United States and Canada. Some of the participants in recent years have been the École polytechnique de Montréal with a quasiturbine engine and students from École de technologie supérieure of the UQAM with a less polluting two-stroke engine using E85 and direct injection. Noise
Maximum noise restrictions have been enacted by law for both production snowmobiles and aftermarket components. For instance, in Quebec (Canada) noise levels have to be 78 decibels or less at 20 meters from a snowmobile path. Now in 2009, snowmobiles produce 90% less noise than in the 1960s. . However, noise has cumulative effects on users and people living near those trails that are not well researched. It is still the origin of numerous complaints. Efforts in regard to noise reduction have now generally shifted to suppressing mechanical noise of the suspension components and tracks. Ski-doo has introduced its "silent track technology" on some production models. Terrain and wild life
Scientific studies have shown that damage is caused to the terrain on or around heavily used snowmobile paths. The snow becomes compacted and any winter rain may flood surrounding areas. This hard snow is more thermally conductive and the underlying ground will freeze to a greater depth, possibly affecting plants and leading to erosion of soil in the spring. Furthermore, snowmobiles can damage shoots and saplings they pass over.  Effects on animals are more difficult to assess; some studies suggest that animals stay away from the snowmobile trails due to the noise, others indicate that some animals are actually using these trails when there is little traffic. Invasive species may use those paths to spread, such as in Utah, were coyotes are encroaching into lynx habitat . Economic Snowmobiles are used by reindeer herders.
Snowmobilers in Canada and the United States spend over $28 billion on snowmobiling each year. This includes expenditures on equipment, clothing, accessories, snowmobiling vacations (lodging, fuel, and food), maintenance, etc. Often, this is the only source of income for some smaller towns that rely solely on tourism during the summer and winter months, while it still has a major economic impact on larger cities and towns as well. Accidents and Safety Brand-new Arctic Cat M7 crashed into tree after rider lost his grip
Due to their inherent maneuverability, acceleration and top speed capabilities, it requires skill and physical strength to control a snowmobile. Snowmobiling injuries and fatalities are relatively rare when compared to other types of transportation such as automobiles and motorcycles. However, losing control of the machine can easily cause extensive damage, injury, or death. A common cause of accidents is when a rider loses control of the machine because they do not have an adequate grip and do not realize how powerful the machine is. This sometimes results in the now rider-less sled crashing into objects such as rocks or trees. Some snowmobiles are fitted with lanyards connected to a kill switch, to prevent this type of accident. However, not all riders use these devices.
It is also possible for a rider, for various reasons to lose control, veer off the trail and flip the machine and/or crash directly into a tree. Also, there have been incidences of decapitation. In an areas they are unfamiliar with, riders drive into suspended barbed wire or haywire fences at high speeds - there have been a number of serious/fatal accidents caused in this way.
Each year, riders are killed when they crash into other snowmobiles, automobiles, pedestrians, or trees or by falling through ice. Around 10 people a year die in such crashes in Minnesota alone with alcohol a contributing factor in many (but not all) cases. In Saskatchewan, 16 out of 21 deaths in snowmobile collisions between 1996 and 2000 were alcohol-related. 
A large number of snowmobile-related deaths in Alaska are caused by drowning.. Because of the extreme cold in many parts of Alaska the rivers and lakes are frozen over for a large part of the winter. People riding early or late in the season run the risk of falling through unstable ice, and heavy winter clothing can make it extremely difficult to escape the frozen water. The next leading cause of injury and death is avalanches, which can result from the practice of "high-marking," or driving a snowmobile as far up a hill as it can go. The practice can be dangerous, but risks can be reduced through education, proper training, appropriate gear and attention to published avalanche warnings. Types of races Snowmobile race Grass drags are held every summer to fall (autumn), with the largest event being Hay Days in Lino Lakes, Minnesota. Hay Days has always been the first weekend following the Labor Day Holiday. The World Championship Watercross or Snowmobile skipping races are held in Grantsburg, Wisconsin in July. The snowmobiles are raced on a marked course, similar to motocross courses, without the ramps and on water. The Snocross racing series are snowmobile races on a motocross-like course. The races are held during the winter season in Northern United States and Canada. One of the largest in New England is the Northeast SnoX Challenge held early January of each year in Malone, New York and run by Rock Maple Racing and sponsored by the Malone Chamber of Commerce. Snowmobile are used for ice racing. The racing is held on an "Ice Oval" track. The World Championship Snowmobile Derby is held each winter in Eagle River, Wisconsin. The "Iron Dog", the longest snowmobile race in the world, is held annually in Alaska. It is 1971 miles long and runs from Wasilla to Nome to Fairbanks. Its name refers to Dog Mushing, long popular in Alaska. Vintage snowmobiling is the racing of vintage snowmobiles and has grown in popularity as a sporting event on the Canadian prairie.