How to replace the sprocket on a Husqvarna chainsaw

replace, sprocket, husqvarna, chainsaw

How to remove the drive sprocket from a chainsaw Husqvarna, Partner, STIHL, Champion

Regular use of many tools requires periodic replacement of their consumable parts. In this regard, you need to know how to remove the sprocket from the chainsaw correctly so as not to spoil the tool.

This part is also called a centrifugal mechanism or clutch disc. To better understand the whole process, you need to understand what an asterisk is and how it is used.

Structural problems, differences between different models

Branded chainsaws have a special design that does not allow replacing a worn drive without dismantling the clutch and other parts of the chainsaw. That is, the saw needs to be almost completely disassembled. modern models of expensive chainsaws are always equipped with a special key.

Also, the owner of a chainsaw may encounter such a nuance: on Chinese imported chainsaws or electric saws, the sprocket on the clutch mechanism may be located in an unusual way. On older models, when the chain teeth are worn out, you need to unscrew and change the drum, one-piece with a drive. On newer models, you can replace the sprocket separately.

Testimonials

Anatoly, Zhitomir:

“I’ve been sawing with a Chinese chainsaw for five years, there is a slight play of the sprocket, I think that because of this, large logs are very difficult for the saw. In the service center, they can’t really say anything, and I don’t know what kind of asterisk there should be, that is, what model to replace so that there is no backlash. The saw is still on the move, there are no other complaints “.

Algorithm for self-replacement of the clutch drum with an asterisk

How is the replacement of the leading sprocket on an electric saw or chainsaw performed. more on this in detail.

Husqvarna 455 Chainsaw sprocket repair

For the procedure for replacing an asterisk, you need to do the following:

  • remove the chain brake cover and pull it towards you (avoid contact of the brake band with the clutch parts);
  • using a wrench, loosen the nuts holding the chain tension and the chainsaw cover;
  • remove the chain and then the bar, removing debris and sawdust from the holes for the fasteners;
  • we fix the piston in the cylinder using a regular cord, but if possible, you need to use a piston stopper or a special lock;
  • the clutch begins to rotate and do this until the piston touches the outlet;
  • after which the stopper or lace is lowered into the candle opening and fixed there, tying several knots (the stopper will fix itself);
  • unscrew the clutch nut (note. the thread of this nut is left-hand, take this into account when unscrewing);
  • it is forbidden to use hard tools so as not to break the soft metal of the clutch nut;
  • then the clutch is removed;
  • after removing the sprocket gear itself;
  • replace the old asterisk with a new one;
  • in reverse order to assemble the structure.

Replacing the sprocket on a Husqvarna chainsaw

Husqvarna chainsaws are powered by two types of drive sprockets. The key sprocket requires replacement of the drum and drive sprocket as the sprocket is welded to the drum. Saws that use a rim sprocket have a replaceable drive rim that can be changed separately from the drum.

Husqvarna recommends replacing the drive rim on the saw every time you change the chain. Painted or flattened areas of metal on the drive rim or drive sprocket are common signs of wear indicating that the drive sprocket is ready for replacement. Even a small amount of wear can have a negative impact on the performance and durability of the saw. If you are wondering how to change the sprocket without problems on a Husqvarna chainsaw, then it is not that difficult.

The drive sprocket and other parts of the saw that drive the chain are located under the sprocket cover on the right side of the saw. Two bolts on the side of the saw secure the cover and guide bar. You can use the tool supplied with the saw or the socket wrench to remove these bolts and cover. The chain must be loosened with the chain tensioner and removed. The drive sprocket is in direct contact with the chain and is located behind the drive rim.

Everyone who works with high quality chainsaws should look at the review of the popular Husqvarna 137 chainsaw, the characteristics are indicated in the article.

To understand how to replace the sprocket on a chainsaw, you need to have access to the sprocket. The sprocket is removed only when the engine piston is stationary. You can access the piston through the hole that the spark plug fits in. The spark plug is located on the top of the engine under the engine cover. This cover is secured with screws or clips on most models. The spark plug is covered with a rubber cap that you can remove by hand. Remove the fork using the tool supplied with the saw or socket wrench. After the spark plug is off, you can immobilize the piston using the piston stop tool inserted through the spark plug hole.

The main signs that the asterisk needs to be changed:

  • the chain has been replaced twice on your chainsaw (one of the current rules for operating a chainsaw and an electric saw. with frequent and active use of the tool, after two chain changes, the drive sprocket should be replaced);
  • the quality of sawing has worsened, the chain needs to be tightened more often;
  • you installed a new chain, which does not fit the old drive sprocket (this part is not universal, and also has its own pitch, in addition, the steps of the drive and driven chain sprockets must match, otherwise the tool will not work);
  • you are using a different bus, shorter or longer.
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Method for a star with a stationary crown

  • dismantling of the protective cover and tire cutting set;
  • locking of the piston part of the motor;
  • disconnecting the clutch from the engine system;
  • notch from the saw body of the clutch and the centrifugal sprocket;
  • visual inspection of the sprocket and its toothed part;
  • if defects are detected, replace the sprocket with a new clutch drum;
  • diagnostics of the chainsaw clutch elements for defects. worn out centrifugal springs and cams can negatively affect the operation of the sprocket;
  • if there are no faults, proceed to the assembly stage. For this you need:
  • remove the stopper;
  • pull back the ignition cable;
  • screw the stopper to fix it on the motor shaft of the centrifugal mechanism;
  • clamp the clutch with a universal wrench in the direction opposite to the chain;
  • return the remaining removed parts to their original positions.

Testimonials

Anatoly, Zhitomir:

“I’ve been sawing with a Chinese chainsaw for five years, there is a slight play of the sprocket, I think that because of this, large logs are very difficult for the saw. In the service center, they really can’t say anything, and I don’t know what kind of asterisk there should be, that is, what model to replace so that there is no backlash. The saw is still on the move, there are no other complaints “.

Saw designs feature

Professional chainsaw from STIHL

In operation, there are already several dozen chainsaws of different manufacturers, capacities, and most importantly for special purposes. Saws are divided into:

  • professional (for felling and construction);
  • household (garden).

Accordingly, the drive gear will be different for them, as well as the sequence of actions. This is a feature of saw gearbox devices. With most professional tools, the tire can change its position on the saw in two planes.

The main malfunctions of chainsaws and actions for their elimination are described here.

Chainsaw drive sprocket device

An asterisk or centrifugal mechanism is a part shaped like a star. It absorbs the engine torque and transfers it to the guide and saw chain. This guarantees the rotation of the cutting attachment and the sawing process itself. It works in automatic mode, which depends on the magnitude of the motor speed.

The clutch drum can be located both outside the chainsaw, and on its inside. under a separate cover. It provides a protective function not only for the material of which the sprocket is made, but also for the operator, who may be injured by it during operation. In addition to the function of the chain rotation, the drive sprocket of the saw prevents the occurrence of malfunctions of the motor system in cases where the chain jams or stops rotating.

Sequencing

The vast majority of household saws are sold under the Partner brand. In them, it is enough to simply change the asterisk even at home by purchasing a repair kit.

Since most often the sprocket in household saws is an assembly mechanism, it rotates due to the bearing. That is, by changing the sprocket, you inevitably change the bearing not to the shaft.

In professional models (such as STIHL and Husqvarna), as well as in household ones, if it is not possible to have a specialized key for removing the star at hand, use a soft cord with a diameter of 5-6 mm.

In all cases, the sequence of actions is as follows:

  • You need to open the side cover to gain access to the tire and sprocket.
  • Next, you need to remove the tire by loosening the chain.
  • After the sprocket is free, you need to unscrew the spark plug to access the engine piston.

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  • By manually rotating the sprocket, bring the piston almost to the very top of the channel and fill the hole formed from the candle as tightly as possible with a soft cord, thereby blocking the movement of the piston.
  • Depending on the saw model and gearbox type, use an open-end wrench and unscrew the sprocket.

Thus, adhering to the recommendations given in the article, you can easily remove the sprocket from the chainsaw yourself.

How to remove and replace the drive sprocket on Husqvarna and STIHL chainsaws is detailed in this

Replacing an asterisk on a chainsaw. how to remove and change it yourself

Gasoline chain saws, like most other tools, require periodic diagnostics of breakdowns and replacement of worn parts. A significant part of them are associated with a drive sprocket for a chainsaw or a clutch disc. one of the important elements of all chainsaws, without exception. Despite the relative simplicity of its design and the tips of the operating instructions, every year thousands of inexperienced craftsmen come to a standstill in this matter and spend money on service centers or produce it incorrectly, which further exacerbate the problem.

That is why we will dwell on this topic and understand the structure, functional features and repair of this working unit of chainsaws.

Replacing the drive sprocket on the Husqvarna 445E chainsaw (435-440-450)

This video shows how you can change a worn out sprocket on Husqvarna 4 Series chainsaws.

Chainsaw clutch closes the sprocket.

First, it is worth noting that when buying spare parts for a chainsaw, you must strictly observe the type of drum or use the advice of a specialist when it comes to modernizing it. Usually, with the simultaneous replacement of the drum and saw chain, the drum bearings are also replaced.

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In any case, the main prerequisite for replacing a sprocket is the wear of its teeth by the chain. In this case, when a one-piece drum is installed in the device, the surface of the chain cuts through it almost one hundred percent, which requires a complete replacement of the entire part. If the chainsaw has a drum with a replaceable crown, then you can limit yourself only to changing the crown.

Usually, in order to remove an asterisk from a chainsaw, many people turn to special service centers, but if there is a need to save a home budget, this work can be done without the help of others. This activity does not look complicated, but it requires you to have all the necessary parts and tools. The process of replacing an asterisk is similar for any device model.

Features of the clutch drum in chainsaws

The drum located in the clutch base of the mechanism is an integral part of the chain drive system. This detail resembles a star in its own form, due to which it got its name. Depending on the type of chainsaw, the part can be professional or household. Because a professional saw is used more often than a household one, then the leading sprocket asks for a constant change. If we talk about household tools, then everything here depends on the amount of work performed and the load that is on the circuit of the device.

In most cases, the sprocket, crown and saw bearing need to be replaced.

In any case, the main prerequisite for changing the sprocket is the wear of its teeth by the chain. In this case, when a one-piece drum is installed in the device, the surface of the chain cuts through it almost one hundred percent, which requires a complete replacement of the entire part. If the chainsaw has a drum with a replaceable crown, then you can limit yourself only to changing the crown.

Usually, in order to remove an asterisk from a chainsaw, many people turn to special service centers, but if there is a need to save a home budget, this work can be done without the help of others. This activity does not look complicated, but it requires you to have all the necessary parts and tools. The process of replacing an asterisk is the same for any device model.

Types of stars

Depending on the class of the chainsaw, all the stars are divided into two groups. professional and household. The first type of parts have increased wear resistance, are made of strong metal alloys that are not subject to corrosion and mechanical damage. Households often require replacement and scheduled repairs; with active use of the tool, diagnostics are recommended every six months. By design features, the following types of asterisks can be distinguished:

  • National teams. The removable ring can be easily unscrewed from the drum axis, which makes it easy to check and replace this part. Almost all European models of chainsaws are equipped with such stars.
  • Whole. They consist of a hub and a stationary crown (the number of teeth may be different, you need to carefully read the instructions for the chainsaw). Due to the factory pressing, the crown cannot be removed separately from the hub, therefore, in case of a breakdown, the entire clutch drum must be disassembled. Such a mechanism is usually found on Chinese models.

If you plan to service the chainsaw on your own, it is recommended to purchase a tool with a professional type of drive sprocket. It should be collapsible, which reduces the cost of repair and maintenance of the tool.

Here you should receive a special repair kit, in which the presence of both a drive sprocket and a bearing is foreseen. Then you should prepare the tool and parts that will be required for the work:

  • a universal wrench sold with a chainsaw;
  • mechanism piston stopper (in standard versions, it is plastic or iron);
  • puller of the centrifugal mechanism or clutch (selected depending on the model of the chainsaw).

During the operation, the following actions are performed:

Chainsaw sprocket location diagram.

  • First, the saw headset is removed, the tire cover nuts are unscrewed with a universal wrench. The cover is removed, the bar and chain are removed.
  • Then the air filter is removed.
  • The saw candle is unscrewed with the universal key. Instead, a prepared piston stopper is inserted, which will allow fixing the position of the piston in the cylinder.
  • The clutch remover fits into the socket of the universal wrench. Then, with the help of the resulting device, the clutch is turned out. All actions must be carried out clockwise.
  • The clutch is removed, freeing access to the internal parts. Now you can remove the sprocket (clutch drum).
  • Depending on the type of drum, it is inspected or the crown is checked. The asterisk or crown is changed to new ones. When installing new parts, you need to painstakingly check the condition of the clutch separator. Special attention should be paid here to the springs of the centrifugal mechanism and the cams. If severe wear is detected, these parts also need to be permanently replaced.
  • If the condition of the parts does not cause any complaints, all parts of the chainsaw are assembled in a reverse sequence. First, the piston stopper is turned out, the starter cord is stretched, then the stopper is screwed in again. Such complex actions allow you to clamp the centrifugal mechanism of the chainsaw on the crankshaft.
  • Using the universal key, the clutch is clamped counterclockwise, in other words, against the rotation of the chain.
  • After that, all nodes and parts can be successfully screwed into their original places.

In order to change the asterisk on the chainsaw, all work must be done carefully and carefully.

Without the presence of special devices, repair work can end in failure: not only the star or the centrifugal mechanism can break, but also the saw chain.

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As you can see from the information presented, the question of how to remove the asterisk from the saw can be successfully solved on your own. Once performed, the operation will allow you to perform it again and again, as the need arises, and attention and accuracy will be the key to a job well done.

Leading asterisk. Correct selection and replacement

The transmission of chains of a chainsaw of any design determines the performance of the tool. In addition, during the operation, the chain will stretch and the teeth of the drive sprocket will wear out. An illiterate choice of sprocket will significantly reduce the durability of the chainsaw teeth, and its incorrect setting will lead to premature wear.

Features of the clutch drum in chainsaws

The drum located in the clutch base of the mechanism is an integral part of the chain drive system. This detail resembles a star in its own form, due to which it got its name. Depending on the type of chainsaw, the part can be professional or household. Because a professional saw is used more often than a household one, then the leading sprocket asks for a constant change. If we talk about household tools, then everything here depends on the amount of work performed and the load that is on the circuit of the device.

In most cases, the sprocket, crown and saw bearing need to be replaced.

Unit clutch design

Chainsaws are units that are equipped with drive sprockets, which are a single complex with a clutch basket.

How to replace chainsaw drive sprocket/rim sprocket Husqvarna 359

The clutch engages automatically, depending on the number of engine revolutions.

A centrifugal clutch is installed on the units, which works in automatic mode, depending on the number of engine revolutions.

When the engine of the unit is idling or at low speeds, the elements of the clutch basket, which have friction linings, have a certain level of freedom in the radial direction. The presence of freedom of movement leads to the fact that, under the action of the springs, the elements are attracted to the center of the rotation shaft and do not transfer the rotational motion to the sprocket drum. With an increase in the engine speed of the apparatus, the centrifugal force exceeds the force of the springs, which leads to the displacement of elements with friction linings. These elements are pressed against the inner walls of the drum under the action of centrifugal force. Due to this contact, the rotational movement is transmitted to the drum and the sprocket, which drives the saw chain of the tool. The chain saw sprocket can be located either outside the tool, or under a special cover that protects the mechanism from damage, and the operator of the device from injury.

The main advantage of this type of clutch is that when the saw chain is jammed, elements with friction linings slip, which protects the internal combustion engine from serious damage.

The sequence of repair work

At the first stage, the saw headset is dismantled, the guide bar cover is removed. After removing the cover, the guide bar and saw chain are dismantled. The fastening nuts are unscrewed using the universal wrench, which is included in the delivery set of the unit.

After removing the saw chain and guide bar, the air filter is removed. Then the spark plug is removed. In place of the dismantled spark plug, a pre-prepared engine piston stopper is installed. The stopper allows you to fix the position of the piston in the cylinder and prevent the crankshaft from turning. The clutch should be removed using a special puller installed in the socket of the universal wrench. All actions should be carried out clockwise.

After removing the clutch, an approach to the internal parts of the device opens, that is, after removing the clutch, the sprocket can be removed.

After removing the clutch drum, depending on its type, the crown and sprocket are inspected and checked. Depending on the design of this unit, the worn out structural elements are replaced. When carrying out repairs, special attention should be paid to the springs of the centrifugal mechanism and its cams. If wear is found, replace them.

If the components do not cause any complaints, all structural elements are installed on the chainsaw in the reverse order. First of all, unscrew the piston stopper and pull out the starter cord, after which the piston stopper is installed in place. This complex sequence of operations makes it possible to clamp the centrifugal mechanism onto the crankshaft of the unit. The clutch is installed in place and clamped using the universal wrench supplied with the chainsaw. Clamping with a key should be done counterclockwise.

The last stage of the repair work is the installation of the remaining structural elements of the device.

When replacing the sprocket, all work must be carried out carefully and with care. All repair work must be carried out using special tools, otherwise the centrifugal mechanism or the saw chain may be damaged.

Tips: how to remove a sprocket from a chainsaw

  • Features of the clutch drum in chainsaws
  • Method for changing the clutch drum

Many tools require constant replacement of consumable parts. This also applies to drinking. That is why the question of how to remove an asterisk from a chainsaw, which is still often called a clutch disc or a centrifugal mechanism, is very relevant to home craftsmen. In this regard, you need to discern what is called an asterisk and for what purposes it is needed.

The clutch drum, called an asterisk, is an integral part of the chainsaw.