How do Snowmobiles Work? [The Basics of Sleds!]


Snowmobiles work in similar ways as motorcycles and ATVs. They have a metal chassis that houses the engine, and the drivetrain. The engine drives the clutch, which transmits power towards the track. While the track rotates the whole machine moves forward. Snowmobiles also feature skis and a steering system, which allows the rider to control them.

If you want to learn more about how snowmobiles work, you are in the right place. We at PowerSportsGuide have compiled all the basics of sleds under one roof!

How do Snowmobiles Work?

Simply put, a snowmobile has seven major parts:

  • Chassis
  • Suspensions and skid
  • Engine
  • Drivetrain
  • Track
  • Steering system and skis
  • Braking system

In the following sections, we’re going to take a closer look at these parts one-by-one.

Would you like to learn more? Let’s drill into the details!

How do snowmobiles work?

What is a Snowmobile Chassis?

The chassis of a snowmobile is the huge metal frame. Simply put, it’s the rigid “base” of the snowmobile on which all the other parts are mounted. The chassis features the tunnel and a metal frame that surrounds the engine. It’s safe to say that the chassis is one of the most important parts of every snowmobile. That’s why the VIN number is also mounted on its side!

Snowmobile chassis are built strong enough to tolerate the dynamic forces caused by bumps and jumps.

If you are seeking huge jumps and are afraid that the chassis of your sled could bend or break, you can make it stronger with a brace kit.

If you are wondering how to strengthen your chassis, or are just curious about how a bare snowmobile chassis looks, don’t miss this video!

It’s a lesser-known fact that the sides of a snowmobile are called PTO and MAG sides. Are you wondering what these terms mean?

What is the PTO side of a snowmobile?

PTO stands for “Power Take Off.” This means that the PTO side of a snowmobile is the side where the clutch is mounted. As the crankshaft can be found on this side as well, the clutch allows the engine power to “take off” here.

What is the MAG side of a snowmobile?

The MAG side of a snowmobile is on the opposite side of the PTO. The term MAG refers to magneto, where electricity is generated on a snowmobile. This electricity is used for the electronic accessories and lights, and to generate sparks in the cylinders. That’s why the MAG side is often called the Magneto side as well.

Snowmobile Suspensions and Skid

As a rule of thumb, every snowmobile features front and rear suspensions. Featuring suspensions means higher comfort, better handling, and safety! The front suspensions are mounted between the skis and the chassis, while the rear suspensions are the part of the skid. The skid is the rear suspension assembly, which contains the arms with the suspensions, the rails with sliders, and the idler wheels.

The roles of the skid are to absorb and dampen the bumps and accommodate the track. When the snowmobile is in motion, the track is running on the sliders while being supported by the idler wheels.

Snowmobile suspensions can be springs and shocks depending on the model. Some sleds have only shocks, while others are manufactured with torsion springs and shocks as well. The shocks are typically filled with oil or compressed air, depending on the model.

You can typically find two suspensions in a skid, the front arm and rear arm suspensions.

Besides the chassis and the suspensions, snowmobiles also need a power source to move. Let’s see how it works!

How do Snowmobile Engines Work?

Snowmobile engines work in a much the same way as motorcycle or car engines. They are regular internal combustion engines, which means they transform thermal energy into mechanical energy. The thermal energy is generated by burning the air-gas mixture in the cylinders. The majority of snowmobiles feature a 2-stroke engine, while you can find some sleds on the market with 4-stroke engines.

The pistons in the cylinders drive the crankshaft, which transmits power to the clutch.

You can read more about snowmobile engines here!

Snowmobile Clutches

Every snowmobile has a CVT transmission (Continuously Variable Transmission). How does it work? Simply put, a CVT clutch features two pulleys, which are often called clutches as well. The primary clutch is driven by the engine crankshaft. As you apply some throttle, the clutch engages and starts to rotate the secondary clutch with a drive belt. Finally, this secondary (or driven) clutch transmits power towards the track.

How does a Snowmobile Drivetrain Work?

The snowmobile drivetrain features no less than ten major parts before it starts to drive the track, not to mention the bearings, bolts, and many other smaller parts! In a nutshell, here is how a snowmobile drivetrain work:

Crankshaft > Primary clutch > Drive belt > Secondary clutch > Jackshaft > Chaincase (Drive gear > Chain > Driven gear) > Driveshaft > Track drivers > Track

The role of each component is as follows:

Crankshaft: This is the shaft that comes from the engine. The pistons rotate the crankshaft, which transfers engine power to the clutch.

Clutch: The clutch controls the connection between the engine and the track. While the engine idles, the clutch doesn’t transmit any power, so the track remains stationary. But at a certain RPM the clutch engages and starts to rotate the driveline, which sets the track in motion.

Jackshaft: The jackshaft connects the clutch and the chaincase. It’s a long metal shaft that goes completely across the sled.

Chaincase: This is an intermediate gear reduction drive system.Simply put, the chaincase reduces the RPMs before it reaches the track. It’s good to know that the clutch as well as the jackshaft rotates near the same RPM as the engine. Since it wouldn’t be good if the track rotated with the same RPM of the engine, the gears in the chaincase reduce it to the right level.

Driveshaft and track drivers: The driven gear in the chaincase rotates the driveshaft. The track drivers are mounted on this shaft and as their names suggest, they drive the track.

Would you like to know how snowmobile tracks work? Keep reading!

How do snowmobiles work? – (Top view)

How do Snowmobile Tracks Work?

How do snowmobile tracks work? Simply put, the track of a snowmobile is mounted on the skid and runs on the sliders, which are tightly connected to the rails. The track drivers rotate the track, which moves the snowmobile forward. The track features lugs (or paddles) to get a better grip in the snow.

The tracks of trail snowmobiles usually have shorter lugs and are sometimes studded for increased friction.

The track is also supported by the idler wheels. They have basically two functions, keeping the track in alignment and to set its tension.

How do Snowmobile Steering Systems Work?

Snowmobile steering systems work in a very similar way as a motorcycle steering system. It features a handlebar connected to a pair of skis. If you turn the handlebar left, the skis will turn in the same direction, which eventually turns the whole machine to the left as well. At higher speeds and in deep snow you will also need some “bodywork” to steer the snowmobile perfectly.

It means you have to lean into the turns and continuously shift your weight!

Do snowmobiles have power steering?

Unlike cars, the majority of snowmobiles don’t have power steering. Surprisingly, Yamaha is the only manufacturer that offers this on snowmobiles. Thus, if you are looking for a sled with power steering, you should take a look at the Yamaha Apex. Your other option is to invest in a snowmobile power steering kit, which fits on many other sleds.

Why do snowmobiles have skis?

The skis on snowmobiles actually have two roles. They displace the weight on a bigger surface, which helps keep the snowmobile afloat in deep snow. The wider the skis, the more flotation they have. Their other role is that they steer the snowmobile in the snow. In fact, they do the same job as the front wheels on motorcycles!

To make the sled steerable, the skis are typically equipped with wear rods. These small metal rods are mounted on the bottom of the skis and features sharp carbides on their bottom.

Are There Brakes on a Snowmobile?

Yes, every snowmobile is equipped with brakes for safety reasons. The majority of sleds come with hydraulic disc brakes. This system features a disc, a caliper with brake pads, and hoses that connect the brake levers and the caliper.

How do snowmobiles stop?

You can stop a snowmobile by simply using the brake lever. You can find it at your left hand on the handlebar, while the throttle control is mounted on the right. If you pull the brake lever, the brake pads contact the disc, which is connected to the driveshaft. The disc slows down the shaft and the track as well, which finally stops the snowmobile.

It’s good to know that most snowmobiles are equipped with emergency brakes, which are also called parking brakes. This usually isn’t a separate brake system, just a small clip on the brake lever to keep it engaged.

What are The Parts on a Snowmobile?

Besides these main parts, snowmobiles feature many other parts and accessories. For your convenience, we’ve gathered all snowmobile parts into one list:

  • Chassis with the tunnel (includes the VIN number plate)
  • Seat: forone, sometimes for two or three riders depending on the model
  • Body: hood, belly pan, side panels, other body panels. Typically made of fiberglass
  • Windshield
  • Gauges/LCD screen
  • Lights: head light, tail light, brake light, reflectors
  • Fuel tank and oil tank (on oil-injected 2-stroke sleds)
  • Air filter
  • Engine: with fuel injection system/carburetor depending on the model
  • Turbocharger with intercooler (on some high-performance models)
  • Cooling system: heat exchanger, pump, coolant, coolant bottle, hoses, thermostat, water jacket (around the engine). Or just a fan with the fan belt on air-cooled sleds.
  • Exhaust system
  • Electric start/pull chord
  • Drivetrain: clutch (clutches and the drive belt), jackshaft, chaincase (gears and chain), driveshaft, track drivers
  • Skis: Ski loops, ski saddles, wear rods with carbides
  • Spindles and A-Arms
  • Front suspensions
  • Handlebar: throttle control, brake lever, ignition switch, grips, deflectors, and buttons for the bells and whistles
  • Mirrors
  • Running board: footrests mounted on the side of the tunnel
  • Skid: front arm with front suspension, rear arm with rear suspension, rails, sliders (hyfax), idler wheels, front strap limiter
  • Track: lugs, clips, studs (optional).
  • Tunnel protectors: it keeps studs away from the heat exchanger
  • Snow flap: do the same job as mud flaps on cars
  • Braking system: disc, caliper, brake pads, hoses
  • Rear bumper
  • Other optional accessories
Parts of a snowmobile

Conclusion

So, how does a snowmobile work?

If you start the engine, the carburetor or injector forces gas/air mixture into the cylinders. The sparks caused by the plugs cause explosions that start to move the pistons and the crankshaft.

If you hit the throttle, the clutch engages and starts to transmit engine power towards the track. How?

Simply put, this is a short overview of a snowmobile drivetrain:

Crankshaft > Primary clutch > Drive belt > Secondary clutch > Jackshaft > Chaincase > Driveshaft > Track drivers > Track

This means power is transmitted through all of these parts before it reaches the track. Finally, the track starts to rotate and propel the snowmobile. The complexity of this system is one of the reasons why snowmobiles are not among the most reliable powersport vehicles!

Besides the drivetrain, many other parts of a snowmobile require continuous attention and maintenance.

If you want to learn more, don’t miss our detailed related posts about the key parts of snowmobiles!

References:

https://adventure.howstuffworks.com/outdoor-activities/snow-sports/snowmobile.htm

https://www.explainthatstuff.com/how-snowmobiles-work.html

https://www.snowmobile.com/products/hayes-trail-trac-brake-system-review-1812.html

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