A snowmobile has two different clutches that work together to transfer and regulate power from the engine, so it becomes energy to drive the track forward, and you move. Clutches are connected to the driveshaft, which spins due to the engine power output.
How does a snowmobile clutch work? I will teach you everything you need to know to understand how this simple mechanism can move your snowmobile wheels forward or sometimes reverse.
A snowmobile clutch works by spinning to propel the shafts that drive the wheel track forward. The driveshaft from the engine is directly connected to the clutch to provide its power, and inside a snowmobile, a pair of clutches are connected by a belt. The primary clutch moves the secondary clutch to transfer energy into forward motion for riding.
How Does A Snowmobile Clutch Work
In the simplest terms, a snowmobile clutch works by taking energy in the form of rotation from a driveshaft and moving it to other parts that drive the wheel track forward.
However, that’s a bit oversimplified even for this basic machine. Below I explain the parts, how the two different clutches work together, what a CVT is and does, and a bit about snowmobile clutch kits.
Snowmobile Clutch Components
Snowmobile clutches are a type of pulley. However, these simple machines are made more complex by the addition of a few components that primarily help control your speed.
Below are all the components of a snowmobile clutch:
- Stationary Sheave or Half – A stationary sheave or stationary half is the part of the primary clutch attached to the driveshaft.
- Moveable Sheave or Half – The moveable sheave or half is the part that changes position to shift gears by moving the belt to a broader or narrower arc.
- Clutch Weight – Clutch weights are literal weights that press in on the moveable half to change how the belt circles the clutch.
- Spider Tower – The spider or spider tower moves with the moveable half.
- Belt – The belt is a circular strip of flat, durable rubber that goes around the clutches.
- Pressure Spring – This is a coiled steel spring.
- Torque Cams – Torque cams are wedge-shaped pieces only found on the secondary clutch.
Note: There are also attaching pieces like nuts and bolts in a snowmobile clutch. However, since these are not novel and only serve to hold parts in place, I did not include them as a component. Additionally, some snowmobile models have
Snowmobile Clutch Diagram
Knowing the names of all the parts in a snowmobile clutch is not the same as understanding how they work together.
I will explain how the drive shaft power moves through the clutches and on to move the wheels.
- Driveshaft to Stationery Clutch – Don’t be confused by the name. The stationary half of the clutch is attached to the driveshaft and spins with it. The ‘stationary part’ means it has no tension spring or weights and is fixed around the rotating tube.
- Spider Tower – The spider tower is what the weights press against to press the spring and moveable sheaf inward. From the Snowmobile Fanatics Board, “The spider does not move. The weights are on the moveable sheave, and when you give it the gas, the weights are forced out by centrifugal force. They push against the spiders’ rollers, making the moveable sheave close the clutch. The moveable sheave is bolted to the outside cover. And the spring is in between the spider and the outside cover.”
- Belt To Secondary Clutch – The belt encircles both the primary and secondary clutches. The belt transfers power from the engine, transmission, and primary clutch into the secondary clutch, where the torque cams can cinch down around the belt as needed.
- Secondary Clutch On – The secondary clutch connects to the drive track, which includes gears that slot into the inner treads of the track forcing the wheel to advance around.
Snowmobile Primary Clutch
A snowmobile’s primary clutch is the one that is directly connected to the engine via the driveshaft.
The rotation of this tube makes the halves of the clutch rotate. The higher the RPMs, the faster they move.
This is the only clutch with weights to change the radius of the belt rotation by pushing the horizontally inward sloped sides of the two sheaves together or letting them move apart.
Your primary clutch sits on the transmission block and connects to the secondary transmission by a belt.
Both primary and secondary clutches have tension springs, but only the primary is connected to the driveshaft and, through it, the transmission.
Snowmobile Secondary Clutch
The secondary clutch in a snowmobile varies from the primary in several significant ways.
First, it doesn’t connect to the driveshaft or have weights. However, this clutch has cams.
A spring in the secondary clutch operates the cams or wedges, which are responsive to torque.
As the engine’s RPM rises and the primary transmits power, these cams squeeze together and tighten the belt. The process continues as the snowmobile increases speed.
Additionally, it is the secondary clutch that connects to the track drive. Without this connection, your track would not move, and your snowmobile would be a fancy doorstop.
The drivers are gears that turn and force the rubber tread to rotate around a series of idler wheels to advance.
How Does A CVT Clutch Work
A CVT clutch works by changing the diameter of the pulley. The belt goes around seamlessly.
This is accomplished by using a pulley with two sides sloped toward the center so that pulling them apart gives the belt a small space to rotate around.
Similarly, pressing those halves together with weights forces the belt to move up the slope to a broader diameter circle of rotation.
The process results in the belt going from a large to small gear ratio without ever needing to move to a different track.
The ‘continuous variable’ means it uses one single gear (pulley) that can change the size up and down based on how many RPMs you run.
Shifting becomes automatic within the engine when you use this efficient system.
If you want to see the motion of CVT in action, I highly recommend this video from Team Industries TV.
In it, they show how the spring tension causes the two parts of the clutch to move together, offering a visual demonstration of how the slopes can go from a narrow diameter to a wider one without the need for chunky gear shifts.
Snowmobile Clutch Kits Explained
A clutch kit is a relatively inexpensive mod you can install on your snowmobile. These kits are known for providing high value.
By installing a clutch kit, you can decrease your gas use, saving money and eventually paying for itself.
Clutch kits help maintain RPMs while running, which is especially useful going uphill.
Additionally, a kit can help extend your belt life and help cool down the clutches. Many sled enthusiasts consider kits a necessary upgrade to any model.
Helpful Tips To Know About How A Snowmobile Clutch Works
Snowmobile clutches are modern pulleys. The pulley is one of the 7 simple machines that almost all human technology is built around, which means understanding and using it is relatively simple.
Here are a few more interesting and helpful tips to know about how a snowmobile clutch works.
- A working clutch is essential to snowmobile function. Fortunately, you can usually tell when something is wrong with the clutch because your machine will ‘tell’ you. If you hear noises coming from your engine compartment, it’s time to stop immediately and get your clutch checked. Likewise, if the engine is bogged down or sluggish and not performing as well as it used to, it may be a clutch-related issue. Finally, pay attention to your shifting to diagnose potential clutch issues. It is most noticeable when you have problems with back shifting. Never let engine and clutch problems go on too long. You don’t want to get stranded on your next ride.
- Your snowmobile’s clutch engages at roughly 3500-4200 RPMs and idles around 1500 RPMs.
- According to Played On Ice, “With proper maintenance, a snowmobile clutch will typically last between 5,000-10,000 miles before it needs repairs or replacement. If you don’t perform regular maintenance to your snowmobiles’ primary or secondary clutch, you can expect them to last between 3,000-5,000 miles before you run into issues.”
Your snowmobile clutches are a vital component that helps to transfer the power generated in the engine into physical forward motion.
Having two clutches allows your machine to have a CVT or continuously variable transmission that passes through a nearly infinite number of gear ratios and gives you a smooth ride over varied winter terrain.
The two clutches, also known as pulleys, are connected by a belt, and only the primary pulley is connected to the driveshaft.