Snowmobile Clutch – What is the Purpose of Clutches in Snowmobile?
Approximately 80% of the annual snowmobile use is for recreational purposes and are widely used in arctic territories. It is also used for different utilitarian purposes.
The snowmobile engines are very much alike to the engines found in personal war craft. 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 which 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.
What is the purpose of clutches in snowmobile?
The primary purpose of the clutch is to smoothly transmit the power from the engine to the jackshaft and to remove the connection when the engine is in neutral position so that the machine is not always rolling. It helps in the smooth delivery of power 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 the 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 infinite 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 snowmobile clutches work?
This system consists of two pulleys or clutches which is 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 track 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 car with an infinite number of gears that you never felt shift.
How to clean snowmobile clutches?
Do you have low speed acceleration or bog issues in your snowmobile? Believe 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 horse power 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 includes 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 very important 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 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 thread 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 be never 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 important to maintain the tension.
It should be made sure that every part of the clutch is covered and the entire glaze from the centre to the outside edge is removed. Always a rough cloth of emery should be used for the cleaning not a 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 have become an expert on 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 basic mechanical knowledge of the system and an easily change your sled’s clutch and belt on your own.