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There are three types of clutch systems used on motorcycles, ATVs and side-by-sides: multi-plate clutch, centrifugal clutch, and sheave clutch.
Multi-Plate ClutchesThe multi-plate clutch is the standard type of clutch, as found on millions of cars, trucks, motorcycles and ATVs. A multi-plate clutch takes power from the engine and transfers it to the transmission input shaft, from where it's sent via the gearbox and chain to the rear wheel(s).
The multi-plate clutch operates as follows:
The crankshaft from the engine is connected to a drive gear that's part of the outer clutch basket. As the crankshaft spins, it rotates the clutch basket. Within the outer basket is a smaller inner basket called the clutch boss, which is connected to the transmission. Between the inner and outer baskets are a set of friction clutch plates that connect to the outer basket, and a set of drive clutch plates that connect to the inner clutch basket.
NOTE: The clutch plates are sometimes called clutch discs.
The clutch plates are covered by a top plate called the pressure plate, and a set of springs. The pressure plate presses down onto the clutch plates so that the friction plates bind against the drive plates and lock together.
As the crankshaft rotates the outer basket, the locked clutch plates cause the inner basket to rotate as well, which in turn rotates the transmission input shaft, which in turn drives the gearbox, chain and rear wheel(s).
When the clutch lever is engaged, it pushes the springs, which lift the pressure plate and allow the clutch friction and drive plates to spin freely from one another. This allows the outer basket to continue rotating while the inner basket stops rotating. By allowing the inner basket to stop rotating, the power from the engine is prevented from going to the transmission and driving the rear wheel(s).
Centrifugal ClutchesThe centrifugal clutch uses the centrifugal forces generated as it rotates to either engage or disengage the clutch mechanism. The exact design and layout of centrifugal clutches varies, but most operate as follows:
The crankshaft from the engine is connected to a central drive shaft within the centrifugal clutch.
As the crankshaft spins, it rotates the clutch drive shaft. The complete centrifugal clutch assembly is housed in an outer clutch drum, which is connected to the transmission.
Between the central drive shaft and outer clutch drum is a spring or set of springs that is/are attached to the drive shaft. At the other end of the spring(s) is/are a set of weighted clutch shoes. The tension of the spring(s) prevents the clutch shoes from coming into contact with the inner face of the clutch drum.
When the crankshaft rotates the drive shaft, the drive shaft rotates the spring(s) and the clutch shoes. As the rotational speed increases, the centrifugal force of the weighted clutch shoes increases, pushing them outward despite the tension of the spring(s) until they contact with and bind against the inner face of the clutch drum.
Once the clutch shoes engage with the clutch drum, they cause it to rotate as well, which provides drive from the engine to the transmission, which in turn provides drive to the rear wheel(s).
Sheave clutches are used with continuously variable transmissions (CVT), and are designed to enable the engine to run at the RPMs that generate the most power at any given speed.
The sheave clutch system is made up of a primary or drive clutch and a secondary or driven clutch, and the system operates as follows:
The crankshaft from the engine is connected to a primary clutch; the primary clutch is connected via a drive belt to a secondary clutch; and the secondary clutch is connected to the transmission.
NOTE: The primary clutch is sometimes called the drive clutch, and the secondary clutch is sometimes called the driven clutch.
The primary clutch has a stationary sheave and a movable sheave that house the drive belt. The movable sheave has a compression spring and set of fly weights that determine how far apart the movable and stationary sheaves are in relation to one another.
The secondary clutch also has a stationary sheave and a moveable sheave that house the drive belt. The moveable sheave has a compression spring and a helix that determine how far apart the moveable and stationary sheaves are in relation to one another.
As the driveshaft rotates the primary clutch, the centrifugal forces generated by the fly weights cause the moveable sheave to push inward toward the stationary sheave, thus narrowing the gap between the two sheaves. The higher the RPMs from the engine/driveshaft, the narrower the gap between the sheaves.
When the gap between the sheaves narrows, it pinches the drive belt and forces it outward toward the outer edge of the sheaves, thus altering the gearing and allowing for greater speed. As the drive belt rotates the secondary clutch, the centrifugal forces generated on the helix cause the moveable sheave to push outward away from the stationary sheave, thus increasing the gap between the two sheaves.
The higher the RPMs from the drive belt, the larger the gap between the sheaves.
As the gap between the sheaves widens, it allows the drive belt to move toward the center of the sheaves, thus altering the gearing in the same way as shifting from a large sprocket to a smaller sprocket on the rear sprocket set of a bicycle alters the gearing and allows for greater speed.
Now that you know about the different types of clutches and how they work, watch the video below to see a clutch removal and installation in action.
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The clutch system in your ATV is the main connection between your vehicle and the wheels’ controls.
It’s an important constituent of the overall transmission system that doesn’t get much attention when everything works well. How does a clutch work?
An ATV clutch works by ensuring stability in the power generated from the ATV engine to work with a transmission. The mode of operation in a clutch will vary depending on whether it is a sheave clutch or a centrifugal clutch. It can also use a multi-plate clutch design.
The rest of the article will look at the different types of clutches you may find in an ATV and how they work.
A clutch is an integral unit in any vehicle’s power transmission, and an ATV is no different. When your ATV is on, the engine spins all the time, but the wheels do not.
The clutch ensures smooth engagement between the spinning engine and the transmission, ensuring that there’s no slippage between them.
There are three main types of clutch you can find in any ATV model today.
They are the sheave clutch, centrifugal clutch, and multi-plate clutch.
These clutches are mostly used in ATV models fitted with automatic CVT (continuously variable transmissions) systems. They are built to ensure the engine is constantly running at the best RPM needed to generate the highest power possible at any speed level.
This system consists of a primary and secondary clutch. These are also known as the drive/driven clutch.
The ATV engine’s crankshaft is linked to the primary clutch, which is joined to the secondary clutch through the drive belt. Finally, the ATV’s secondary clutch is linked to its transmission.
The primary and secondary clutches have movable and stationary sheaves where the drive belt fits.
The moveable sheave is fitted with a spring for compression and some flyweights. The weights are useful because they help the stationary and movable sheaves to maintain an appropriate distance.
When your engine is running and the driveshaft spins, centrifugal sources move the flyweights and the stationary and movable sheaves around to force a gear change and deliver higher speeds when you need it.
Here’s a video showing the install of a sheave clutch:
The centrifugal ATV clutch gets its name from the fact that it relies on the centrifugal force generated while it is rotating to activate or deactivate the clutch system.
Different manufacturers have different designs and layouts for centrifugal clutches, but the operation mode is similar across the board.
The ATV engine’s crankshaft is hooked to the central or main drive shaft inside the clutch system.
While the crankshaft rotates, the drive shaft spins with it. The entire clutch system is contained inside an external clutch drum linked to the ATV transmission.
A collection of springs linked to the ATV drive shaft nestles between the outer or exterior clutch drum and the central drive shaft. Some clutch shoes (weighted) are affixed to the other extreme of the springs.
These shoes don’t interact with the clutch drum’s inner side due to the tension delivered by the springs.
The ATV’s drive shaft spins both the shoes and the springs as the crankshaft spins. With an increase in the speed of rotation, the shoes’ centrifugal force also increases. The force pushes the shoes outward, so they can come in contact with the clutch drum’s inner face and bind against it.
As soon as the shoes come in contact with the ATV clutch drum, the drum will spin, providing drive or power from the ATV engine into the transmission and the rear wheels.
Here’s a video showing how a centrifugal clutch works:
A multi-plate clutch is a popular option found in many ATV models. It receives power from an engine and channels it to the input shaft of the transmission. From here, the power moves to the rear wheels through the gearbox.
The crankshaft coming from the ATV engine is linked to a drive gear joined to the outer clutch basket. The clutch basket rotates as the crankshaft spins. Inside the outer basket, a clutch boss (a smaller inner basket) is linked to the ATV transmission.
A set of friction clutch plates (also known as clutch discs) separate the inner and outer baskets. A section of the plates is joined to the outer basket while some drive clutch plates hook up to the inner clutch basket.
The clutch plates are protected from the top by a set of springs and the pressure plate.
The pressure plate is designed to hold down the clutch plates to ensure the friction plates are bound tightly to the drive plates for a clean lock.
As the crankshaft rotates the outer basket connected to it, the tightly locked clutch plates trigger rotation in the inner basket as well. The result is rotation in the ATV transmission input shaft, which drives the ATV’s gearbox and rear wheels.
Here’s a video showing the operation of a multi-plate clutch:
We’ve seen a peek into what happens under the hood with the main types of ATV clutches. The convoluted nature of the systems means that your clutch needs regular maintenance.
If you take your ATV to a maintenance shop, you’ll likely get clutch maintenance by default.
However, if you’re doing the job on your own, there are a few things you should know:
Here are some things to watch out for when inspecting your ATV clutch:
You’ll need to replace the clutch completely in this scenario.These are some of the major maintenance tips to keep in mind for your ATV’s clutch. If you don’t ensure regular maintenance for the vehicle, there is a high possibility that it will develop any of the common problems associated with ATV clutches.
These include clutch slipping, clutch creeping and the attendant pungent smell, and a jerky feel in the lever. Repair these problems will cost more than maintenance in most cases, so give the clutch the desired attention.
Don’t forget to practice sensible clutch use while out riding to reduce the chances of damage. Don’t use your clutch as an aid for braking, and don’t leave your foot on it half the time.
Basically, any scenario that doesn’t make sense with your standard car or motorcycle clutch should be avoided with your ATV as well.
The clutch operation in an ATV is a very elaborate process regardless of the ATV clutch type in your model.
Understanding how each type of clutch works makes it easier for you to deliver regular maintenance if you have the DIY skills. If you don’t have the skill to handle the maintenance, outsource it to avoid more serious damage.
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The ATV clutch is responsible for both gear shifting and vibration reduction during the ride. ATVs for children are no exception.
As a rule, the occurrence of any problems with this component of motor vehicles, the rider feels immediately. It is recommended to service the ATV clutch every 6000-7000 km, but sometimes all kinds of problems can occur earlier. The rate of wear of the functional components of motor vehicles directly depends on the conditions of its operation. nine0003
The following points can serve as a signal that something is wrong with the motorbike clutch:
Depending on the severity of the failure, the problems described above can be solved either by repairing the vehicle's clutch or by replacing it completely. As for Chinese models of ATVs, here it is necessary to check whether the nuts on the clutch are securely fastened. Poor assembly of motorcycles can also cause suspicious sounds in the variator area. nine0003
To change the clutch on a children's ATV with your own hands, you will need:
In general, this procedure is quite simple and fast. In older models of ATVs, everything is somewhat more complicated.
Before proceeding with the dismantling of any components of motor vehicles, be sure to read the instructions from the manufacturer.
Even in Chinese models of ATVs, the clutch boasts an impressive margin of safety, and therefore its breakdown often occurs as a result of improper use of this equipment. nine0003
The main causes of premature ATV clutch wear include:
The only way to prolong the life of your ATV clutch is to use it properly and carefully. It is advisable to use good oil, and do not forget about timely maintenance. nine0003
The use of high-quality clutch discs in the ATV ensures a smooth start of the vehicle, and also fully ensures reliable grip without slipping even under fairly high loads.
The exception is children's electric ATVs, in which there is simply no clutch disc.
ATV clutch usually needs to be adjusted no more than once a year. Before starting work, place the vehicle on a special footboard. nine0003
The process of adjusting the clutch on a motorbike is quite simple, and consists of the following steps:
If it operates too slowly or too quickly, adjust the screw in the desired direction (tighten or loosen). Since adjusting your ATV's clutch is easy, you can repeat this procedure as needed. In the vast majority of motorcycle models, this functional component is adjusted in a similar way. If there are certain nuances in the clutch setting, they are explained in detail in the official vehicle manual. nine0003
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What is a variator? A variator is a mechanical continuously variable transmission.
○ You can buy a Stels scooter in our store by choosing a convenient payment method: cash to the courier, card, credit, installment.
It is used to smoothly change the speed of the output shaft. Basically, a V-belt variator is installed on all types of scooters. It consists of a drive pulley, driven and V-belt and works only depending on the number of engine revolutions, not responding to loads (for example, when climbing uphill, the load on the rear wheel increases, but the gear ratio remains unchanged), which is one of its disadvantages.
. nine0003
Let's start with the simplest. Why V-belt? It can be seen from the figure that the belt in the section has a trapezoidal shape and "wedges" into the pulley only with its side surfaces. When these surfaces wear, due to its shape, it cuts deeper into the pulley and still remains in good contact with it.
How does the gear ratio change? The device of the drive pulley (the drive pulley rotates by the crankshaft) is such that its cheeks, when exposed to centrifugal forces, are smoothly compressed and push the V-belt further and further away from the center of the pulley. At the same time, the driven pulley, on the contrary, unclenches, and the belt on it smoothly sinks closer and closer to the center of the pulley. The higher the engine speed, the more the drive pulley is compressed and the driven pulley is unclenched, thereby changing the gear ratio from the crankshaft to the rear wheel. This process is clearly visible in these figures:
The engine was not launched:
Small engine speed:
Average engine average:
Maximum engine speed:
The drawings also shows the positions of the wedge -shaped belt in the context of the leading pulley (left) driven (on the right) at different engine operating modes.
How is the variator drive centrifugal pulley arranged? Pretty simple!
Let's look at its design shown in the figure:
1 - fixed cheek of the pulley, rigidly screwed to the trunnion (tail) of the crankshaft 5 with bolt 8 with washer 6. The V-belt 2 is placed between the cheeks 1 and 3. The cheek 3 is designed so that it moves freely on the shaft 5. Move it rollers 4 that abut against the stubborn and immovable cheek 9. Under the influence of centrifugal force, the rollers 4 diverge from the center of the shaft 5, thereby shifting the cheek 3 closer to the cheek 1 and pushing the belt 2 further from the shaft 5. The positions of the rollers 4 and the cheek 3 are at different engine speed you have already seen in the four figures above. nine0003
Now a little about the driven pulley (figure below).
It differs from the drive pulley in that it does not have rollers, instead of them there is a spring (see picture on the right). At the moment when the cheeks on the driving pulley are approaching, pushing the belt out, on the driven pulley the cheeks (namely, the cheek 5 moves along the shaft 7, the cheek 6 is rigidly fixed and motionless), on the contrary, they diverge, compressing the spring 3, and the belt goes deeper, which again, it can be seen in the engine operating modes above in the four figures.
Thanks to spring 3, the V-belt is always tensioned, and its tension increases proportionally with increasing speed. This, in turn, allows the belt not to slip at higher speeds, at which the load is greater than at lower ones. nine0003
There are also simpler models of scooters that do not have a variator on the drive shaft. Instead, a simple pulley is installed and the gear ratio from it to the driven one is fixed at all engine speeds. Such models are more than 50 km / h. do not develop and "stupidly" gain momentum from the spot. The driven pulley is the same as that of the CVT - under the spring and serves only to tension the belt. The only plus of such a device is that the belt lasts longer.
Next comes the automatic clutch, which is assembled with the driven pulley. nine0003
What is a centrifugal automatic clutch? This is a mechanical device that automatically, at a certain engine speed, using centrifugal forces, connects the output shaft of the variator to the gearbox.
It is used to smoothly start the scooter without any handles and pedals. Such a clutch is installed mainly on all types of scooters where a V-belt variator is installed.
Let's see how the automatic centrifugal clutch works with the help of the picture:
The output shaft of the V-belt variator 2 (hereinafter referred to as the variator shaft) is mounted on the input shaft of the gearbox 4 (hereinafter simply the gearbox shaft) on bearings 8, and due to this, the two shafts rotate independently of each other at the moment when the scooter is not started or is running at idle.
A plate 2 is installed on the variator shaft, to which the pads 3 are attached (using bushings 7) with asbestos pads 5 glued to them. The pads are pressed under the action of springs 6 towards the center of the variator shaft. At certain engine speeds, under the influence of centrifugal forces, the springs are unclenched and the pads 3 begin to move in the direction indicated by the arrows with the letter C.
