Approximately 80% of the annual snowmobile use is for recreational purposes and is widely used in arctic territories. It is also used for different utilitarian purposes.
The snowmobile engines are very much alike the engines found in personal watercraft. Heavier snowmobile models use four-stroke engines, while lighter models use two-stroke engines. It has four main components (an engine, a clutch system, ski, and tracks) essential for the powering and driving of the snowmobile.
The clutch system of the snowmobile is an essential component of the engine. It was first designed in 1490 for a CVT system by Leonardo Da Vinci, and the first patent for a CVT system was filed in 1886.
So, let’s learn a little more about why clutches are used in snowmobile engines.
What Is The Purpose Of Clutches In Snowmobile?
The primary purpose of the clutch is to transmit the power from the engine to the jackshaft smoothly and to remove the connection when the engine is in a neutral position so that the machine is not always rolling.
It helps in the smooth delivery of power to the engine to enable smooth vehicle movement and perform quietly to reduce drive-related vibration.
The clutch in the snowmobile machine helps the rider to ride uphill in deep powder snow as it keeps the engine at maximum RPM without shifting into a higher gear. All the snowmobiles have a clutch, so you don’t have to worry about a stick shift. The clutch system of the snowmobile is a form of continuously variable transmission (CVT).
Now think about an automatic car. How many gears does a car have? Five or six, maybe. Well, unlike the manual or automatic car, the CVT system means that your snowmobile has an infinite number of gears.
This unlimited number of gears is due to the stepless CVT system. It just moves up and down, at each speed, you stop accelerating or decelerating, and you are at the correct gear for that speed.
How Do Snowmobile Clutches Work?
This system consists of two pulleys or clutches which are connected by a drive belt.
The primary clutch sits on the engine crankshaft. A pressure spring holds the primary’s two halves apart when the engine RPM is low. As the engine begins to accelerate, the clutch weights generate enough centrifugal force to lose the clutch, allowing the belt to move freely and transmit power.
The secondary clutch connects to the tracking device, which turns the wheels and powers the tracks. The cams (wedges) are operated by a spring, and as the engine RPM increases and the primary transmit power, these cams squeeze together and tighten the belt.
This process continues until the snowmobile accelerates. Once it reaches its top speed, the primary clutch loses, moving the belt into a higher gear.
The snowmobile requires less power to accelerate than it did to get started, the secondary clutch opens.
The CVT is called this because, as the engine speed increases, the final drive ratio increases. That is the difference between the engine speed and the track speed decrease. It is equivalent to an automatic transmission in a car with an infinite number of gears that you never felt the shift.
How To Clean Snowmobile Clutches?
Do you have low-speed acceleration or bog issues in your snowmobile? Believe it or not, just cleaning your clutch can easily solve your problem.
Snowmobile clutches have a difficult life. At the flip of a throttle lever, they go from idling to transmitting full power from the engine’s crankshaft to the chassis’ jackshaft. They must perform shifting duties under harsh conditions and rider styles.
Poorly maintained or worn-out clutches can steal the torque and drain the horsepower from the power train. Issues always include the misalignment of the clutches, worn bushings or rollers, or worn or incorrect drive belts.
The cleaning of the clutches is a step-by-step process and all the processes are discussed below one by one.
Cleaning Of The Driven
This is called the launching point of the process. The cleaning and calibrating of the secondary clutch include having serviceable tuning parts like springs, tools, and cleaning supplies in hand.
Like the driven (secondary clutch), the drive clutch (primary clutch) needs a thorough examination and inspection.
Cleaning Of The Drive
It is crucial to have the proper pullers to install and remove the drive clutch. It is also to be noted that the brand of the clutch and the pullers should be the same; otherwise, they may damage each other.
A proper holder should be used to remove or install the retaining bolt and then make sure to apply a dab of grease on the end of the puller bolt and threads to ease the use. The puller bolt is then threaded in until the drive pops loose from the crankshaft taper.
The clutch or the pulleys should be washed and cleaned by rinsing the area with warm water, or also you can use a brake cleaner. This step can never be skipped as the metal dust you just created will get into your clutch’s bearing and rollers. If this happens, you will start to rush into big spare bills.
The belt should never be too loose as your snowmobile will lose its low-end power, and also it can never be too tight as it will squeal like a pig. Thus it is essential to maintain the tension.
It should be made sure that every part of the clutch is covered, and the entire glaze from the center to the outside edge is removed. Always a rough cloth of emery should be used for the cleaning, not steel wool.
You also do not want a shortcut this cleaning process by using compressed air; this will just help to blow the dust into all the areas you were trying to remove it from landing in.
After the whole cleaning and the learning process are completed, you can now enjoy the great winter sledding around.
Congratulations, now you know something about the CVT system and the infinite number of gears. Give yourself a big pat on the back, and after all, it was not as daunting as you thought it was.
Now you have the necessary mechanical knowledge of the system that will enable you to make a quick and easy change of your sled’s clutch and belt all on your own.