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Photo of snowmobiles in a blue dusk light in Alaska.


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by Chris Woodford. Last updated: June 29, 2018.

Snow problem? 's no problem if you have a snowmobile! If you live somewhere warm, like California, your only chance of seeing one of these brilliant little machines is in wildlife documentaries or James Bond films. If you live nearer the Arctic, in Alaska or northern Quebec, snowmobiles (often called snow machines) will be as familiar to you as motorcycles are to people living further down south. Given how useful they are, it's hardly surprising that engineers spent much of the early 20th century trying to develop the perfect machine for speeding over frozen terrain. The small, light, modern snowmobile finally appeared in the 1960s thanks to pioneering Canadian engineer Joseph-Armand Bombardier, who named his machine the Ski-Doo®. So how do these funky little snow bikes actually work? Let's take a closer look!

Photo: A convoy of US Marines on Ski-Doo snowmobiles in Alaska. Photo by Airman 1st Class Jack Sanders courtesy of US Marine Corps.

What is a snowmobile?

Photo of a snowmobile racing down a snowbound road in Alaska.

Photo: A snowmobile makes light work of this frozen track in Alaska. Note how far apart the front skis are compared to a skier's: this gives a snowmobile stability and a lower center of gravity, which helps to stop it tipping over. Photo by Jonathan Snyder courtesy of US Air Force.

Simplified cutaway of a snowmobile showing how the track is powered from the engine by a drive belt.

Artwork: A snowmobile gets much more traction in snow than a motorcycle using a large, wide track with deep rutted treads. A belt-drive and clutch system transfers power from the engine (in the center of the machine) to the track at the back. Compare this with Bombardier's early, 1944 snowmobile design (below) and you'll see that the basic idea hasn't changed very much.

Think about an ordinary motorcycle: you have a heavy engine in the center with the rider balanced on top of it and two narrow wheels with rubber tires just in front and behind. Now in theory you can ride a machine like this through snow, providing the snow is soft enough to compact as you move over it (and you can get some grip) and not so hard and frozen that it's turned to super-slippery ice. In practice, motorcycling on snow and ice is incredibly dangerous and best avoided: steering fluctuates between tricky and impossible and there's a high risk your bike will slide right out from under you. The problem is that relatively little of your bike is actually touching the road—just two tiny patches of rubber under the front and rear tires—and that's simply not enough to give you good traction and grip.

If you had to rebuild a motorcycle for snowy terrain, what would you change? You might fit skis at the front to spread your weight and give reasonable steering. A wide, rutted track at the back would give you plenty of speed and lots of grip, no matter what kind of terrain you had to deal with. What you'd end up with would be something like a modern snowmobile. It's very similar to a motorcycle, with the engine in roughly the same place and power transmitted to the rear track through a drive belt.

What are the parts of a snowmobile?

Photo of a Ski-Doo with the main component parts numbered and labelled.

Photo: A Ski-Doo snowmobile parked up in Alaska. Photo by Airman Laura Max courtesy of US Air Force with added numbering and annotation by

There's lots more to a snowmobile than just an engine, some skis, and a track. Here are a few of the more obvious bits and pieces:

  1. Skis: These curve upward to stop the machine diving into the snow as it plows forward. They also provide effective steering.
  2. Ski handles: These are extra loops of metal on the front of the skis, used for towing or pulling the machine free of snow.
  3. Front bumper: A bit of crash protection!
  4. Shock absorbers: Often made from lightweight but tough aluminum, they absorb energy as the skis hit bumps.
  5. Hood: Fiberglass or tough polycarbonate plastic front cover. Conceals energy absorbing foam to soften impacts.
  6. Engine air vent: Remember there's a gasoline engine inside a snowmobile that needs air to burn fuel. There are usually air vents on the front and sides of the hood.
  7. Dashboard instruments: The latest snowmobiles have LCD display panels including a speedometer (showing current speed and average speed), rev counter, mileometer, engine thermometer, and compass.
  8. Windshield: It measures ~12–60cm (~5–25 inches) from top to bottom. High windshields like this one are good for exploring tricky terrain and provide a certain amount of anti-roll protection; lower windshields are better for racing.
  9. Side reflector: A bit of added visibility!
  10. Foot rest: Somewhere to rest your feet, of course, but also protection from the icy wind.
  11. Throttle (accelerator): Expect a top speed of about 110km/h (70mph).
  12. Brake lever: operates hydraulic disk brakes that stop the rear tracks. Obviously the front skis have no brakes on them!
  13. Seat: There's room for one or two people on most snowmobiles. Some models have heated seat covers.
  14. Idler wheels: These don't provide power: they allow the track to spread over a larger area of the ground, effectively giving a longer track and providing better traction. They also provide suspension. Idler wheels are about 14cm (5.5 inches) in diameter. The idler wheels are the ones colored orange in our simplified cutaway drawing up above.
  15. Track: Sometimes known as the "endless tread." Typically 34–40cm (13.5–16 inches) wide and made from tough materials such as carbon fiber or Kevlar.
  16. Sprocket wheel: The back wheel is typically about 18cm (7 inches) across.
  17. Snow flap: Like the mudflap on a bicycle, this stops snow shooting up from the spinning track at people following on behind!
  18. Luggage rack: Most snowmobiles carry a fuel can here or somewhere on the body.
  19. Tail/brake light.
  20. Seat back rest.
  21. Front headlight: Fitted with one or two powerful 60-watt bulbs with lenses to concentrate the beam.
  22. Rear bumper.
  23. Skid plate: For bumping through snowdrifts.
  24. Wing mirror.
  25. Fuel tank: Holds ~40liters (10.5 gallons) and gives a range of ~300km (~200 miles). Typical fuel consumption for snowmobiles is about 10-20 liters/100 km (10-20 mpg).
  26. Handlebar wind deflectors: Help protect your hands from freezing up in the blast of a chill wind. Snowmobile handlebars generally have heated grips for the same reason.
  27. Engine: Usually a 2-stroke 600cc or 4-stroke 1200cc engine (similar to a medium-to-large motorcycle). Power is transmitted from the engine to the rear track system by a simple drive belt, as shown in our little artwork up above.
  28. Rear shock absorber and suspension.

More interesting features of snowmobiles

Side view of the early Bombardier snowmobile from April 11, 1944.

Photo: Who invented the snowmobile? This early snowmobile was designed by Joseph Armand Bombardier and patented in April 1944. Much like modern snowmobiles, this one has a ski at the front for steering and a sophisticated chain-tread track system at the back. Sprockets pull the tracks around, while idler wheels in between provide suspension. The main difference between this vehicle and modern snowmobiles is the large cabin, which can seat about 12 people. Artwork courtesy of US Patent and Trademark Office (with coloring added by us for clarity).

Skis, engine, a track, and some brakes—a snowmobile sounds simple enough. Under the covers, however, there's a lot more going on. If you take a look at the 500 or so snowmobile-related patents that the leading manufacturer, Bombardier, has filed since 1944, you'll find all sorts of features you might never have thought of. For example, powering through wet or deep snow, it's quite likely the track will clog up, greatly increasing the weight of the drive mechanism and slowing you down. That was why Bombardier developed a snow-expelling mechanism in the 1960s, which consisted of spiral grooved wheels to gouge out impacted snow as the track shuffled past them. Some snowmobiles have retractable headlamps, which flip out of the way when they're not in use. Again, it sounds simple enough, but someone at Bombardier still had to sit down and design a reliable retractable head lamp assembly to make that work. As you might expect, most of Bombardier's patents relate to the track/tread mechanism, suspension, skis, and basic frame construction—the core features of a snowmobile—but it's interesting to browse through their other innovations, which cover everything from quick-release passenger seats and engine turbochargers to more mundane things like electronic engine lubricators!

How safe are snowmobiles?

Snowmobiles are great fun but, like motorbikes, they're fast and heavy machines. In a typical year, 2 million people enjoy snowboarding in North America, but around 200 of them die in accidents and there are 14,000 injuries [Source: Snowmobile injuries in North America by J J Pierz, Clin. Orthop. Relat. Res. 2003 Apr;(409):29-36.]. Now 200 deaths might sound like a lot, but we have to put that number in context. Each year, around 150,000 people die from accidental injuries, 33,000 die from falls, and 38,000 die from vehicle accidents [Source: Accidents or Unintentional Injuries, Center for Disease Control and Prevention, March 2017.].

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Text copyright © Chris Woodford 2010, 2016. All rights reserved. Full copyright notice and terms of use.

Ski-Doo is a registered trademark of Bombardier Recreational Products Inc.

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Woodford, Chris. (2010/2016) Snowmobiles. Retrieved from [Accessed (Insert date here)]

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