Village Science

Snowmachine Tracks


A 8a, 15
B 3
D 1, 3


Surface area

Snowmachines have been in villages long enough that few people under thirty can remember when dog teams were the main form of transportation.

It wasn’t until science and technology develop good material for a track that snowmachines had a chance of being practical. A book on the Klondike Gold Rush described a powered vehicle that the builder thought could travel over snow. It had a large steel track with big teeth. The first journey of this steam powered vehicle was its last. It dug straight down into the earth, unable to get out.


A track made of steel is too heavy for the light engines used in snowmachines. Besides, a steel track would become an icy mass as soon as it got into overflow.

Natural rubber stretches too much to be good material for a track, and it dissolves in gas and oil. Kevlar provides flexibility, strength, relatively low weight, and durability. The strength of the track is increased by putting nylon cords in the track material. This is like putting steel in concrete. The combination of materials is far stronger than either of the materials separately. The nylon prevents the track from tearing, and the Kevlar keeps the nylon from wearing.

Oldtimers understood this same principle. They put beaver fur in spruce gum when they patched a hole in a boat. The beaver fur strengthens the same way the nylon and Kevlar fibers do in the snowmachine track.

Choosing a Track

There are several factors involved in choosing a track:


A longer machine tends to glide over the tops of the bumps and “floats” more on powder snow. However, if the track is too long it will be hard to steer in tight places and takes more power to turn the track.

Short tracks are better for hard trails and sharp corners, as in racing. If the track is too short, the machine will get stuck in soft snow. A short machine tends to give a jerky ride because it goes in and out of all the bumps.


If the track is too narrow, the machine will be tippy. If it is too wide, it will be hard to steer and require a lot of power to drive it. It will also be too wide for the driver to straddle.


If the track is too thin, it will tear. If it is too thick it will take too much power to drive it, especially in cold weather when everything is stiff. Wise operators elevate the rear of the machine and spin the track for a short time before traveling. This loosens the track and prevents burning the belt on cold starts.


The surface of the track is very important. If a track is too smooth, there isn’t enough friction with the surface of the snow, and it will spin out. If the track is too rough, like a machine with racing cleats, it will dig down and get stuck in powder snow. Mountain climbing machines have one- to three-inch paddles on their tracks that allow them to go uphill almost verticle in deep powder snow.

Cleated trackSome tracks have steel cleats across the width. They can pull large loads on hard trails without spinning out. Unfortunately, cleated tracks can slide sideways. A young man went sideways off a windswept mountain top with a brand new machine. He lived, but the machine was destroyed. star

Racing machines often have stars bolted on the track surface. They resist spinning out and they don’t slide sideways.


Basically, if the track is too large, it takes a lot of power to drive it. If it is too small, the machine sinks in powder snow, or it spins out when pulling a load because there isn’t enough surface area in contact with the snow.

There is no perfect track, since one is good for one condition and not good for another. The main things to consider are the surface area, how much flotation and contact are needed, and how much friction is needed. The use of the machine will determine which track to get.

Bogie wheels


Bogie Wheels

The first snowmachines that came to Alaska had bogie wheels inside the track. A snowmachine track is similar to a truck tire. The truck tire is held in shape by air pressure. The snowmachine track is held open by springs, wheels, and rails.

Bogie wheel suspension is good because it causes the track to fit the contour of the trail, keeping as much of the track in contact with the trail as possible, increasing the surface area that is exerting friction. However, bogie wheels represent a lot of springs, bearings, and other moving parts that need maintenance. There aren’t many machines left that use them.

trackSlide Rails

Most newer machines have slide rails that are held in place by a few strong springs. The track actually slides on the rails that are made from a very low friction material called Hifax, a form of Teflon.

Slide rails will wear out rather quickly if there isn’t a little snow lubricating them, particularly on gravel. On a hard trail, a good driver occasionally runs into powder snow to lubricate the slide rails.

Without Hifax or some similar low-friction material, slide rails would not be possible.


Snowmachine skis take a terrible beating and are expected to operate under many different conditions. They not only steer the machine, but they give flotation in powder snow.

They must have enough surface area to keep the front of the machine up, and must also be able to steer on clear ice. Actually, they are designed to have very little friction in a forward direction, and as much friction as possible sideward. Within recent years, manufacturers have produced plastic skins to fit under the skis. They provide a little more surface area for flotation, but their main purpose is to reduce friction with the snow. They work amazingly well.

Some people run their machines on bare tundra, and report that plastic skins are a tremendous improvement. Of course, they don’t last long on gravel roads.

Most skis have a very hard steel skeg down the middle that is designed to help the machine track on hard or icy trails. The skeg is made of very durable carbide steel.

Belly Plastic

In the effort to make snowmachines more efficient while breaking trail, manufacturers have made sheets of plastic to fit under the belly of the machines to reduce friction. The plastic also provides protection from impact with obstacles.

The belly plastic offers that kind of help by reducing friction in powder snow in critical moments.



  1. Put gasoline on a rubber band. What happens? Put a rubber band outside in the cold. How flexible is it below zero? Why aren’t tracks made of real rubber?
  2. Look at the different snowmachine tracks in the village. How do they compare in length and width? Do some have metal cleats? Do any have racing stars? Of all the different kinds, which is the most popular in your village?
  3. Measure the surface area of the tracks plus surface area of the skis of different machines. Compare the surface area to the weights given in the snowmachine specifications. How many pounds per square inch does each one represent? Are there relationships between the psi of trail machines contrasted with racing machines?
  4. Draw the patterns of the bottom of the tracks. Compare them. Compare them with four-wheeler tire patterns. Are there any similarities?
  5. Find old tracks around the village. Compare their thickness. Diagnose why each one broke (cracking, wear in certain places). Try bending a piece of track that has been out in the cold. Try bending the same piece of track once it has been inside for a while. How much difference is there? Speculate how much more power it takes to turn a cold track than a warm one.
  6. Carefully try to cut a piece of snowmachine track. Can you appreciate the technology that made it this tough?
  7. Ask the people in the village what they do when a track breaks far away from home.
  8. What uses have people found for discarded snowmachine tracks in your village?
  9. Compare the suspension systems of the machines in your village. Do some still have bogie wheels? Talk to people that own the two different kinds. What are the advantages of each? Find a discarded slide rail. Does it look like it wore out because of snow or gravel? Try to cut it with a knife. Is it hard? What uses have people discovered for used slide rails? Inquire how much new slide rails cost and how hard they are to install. Identify the part of the track that slide rails run against. How is this different from the rest of the track? Are the bearings on the bogie wheels sealed bearings? What do you think happens when the seals go bad? What can you learn about increasing the life of bearing seals?
  10. Look at the skis on different machines in your village. Talk with people who use the plastic skins that fit under the skis. What do they say? What is the surface area of the average ski? Compare skegs on the different skis.
  11. Measure the distance between the skis on different machines. Is there a difference? If so, why do you think this is so? What do snowmachine owners say about skis being close together or farther apart? Is it important? If so, under what conditions?
  12. Talk to several people who have installed the sheets of plastic under the belly of the snowmachine. Do they notice a significant difference? Why did they install the plastic in the first place?
  13. When did snowmachines first come to your village? Ask the older people how they have changed over the years. What about them has improved? What about them has not improved? Why do they think machines are better than dogs?
Student Response

Student Response

  1. Why wouldn’t a track made out of natural rubber last on a snowmachine in Alaska?
  2. Why are there nylon cords in the track as well as Kevlar?
  3. What is the problem with a very large track?
  4. What is the problem with a small track?
  5. What is the problem with a track that is too smooth? Too rough?
  6. What kind of track would you want to operate in deep powder snow?
  7. What kind of track would you want for racing? For pulling big loads on hard trails?
  8. Skis are designed to have very little friction in a direction, and considerable friction in a direction.
  9. What is the purpose of skis besides steering?
  10. Why do some people put plastic skins on skis?
  11. Why do some people have belly plastic installed?


  1. A machine weighs 375 lbs. The track is 15” x 47” in contact with the trail. The skis are 5” x 30” each with plastic shoes. What is the average psi of this machine on the surface of the snow?
  2. A racing machine weighs 489 lbs. The track is 15” x 40” in contact with the snow. The skis are 5” x 24” each. What is the average psi on the surface of the snow?
  3. A long track uses 25% more energy to turn than a short one. Turning a short track represents 9% of a machine’s effort. If Pete usually spends $350 a year on gasoline approximately how much is he paying for the convenience of having a long track?
  4. Having plastic ski skins and plastic on the belly of a machine saved 12% of a machine’s effort. They cost $75 to purchase. If Moxie usually spends $425 for gas on his trapline, will the plastic on the skis and belly pay for themselves in the first year?

Questions or comments?
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