How to remove an asterisk from a Partner chainsaw

Expert advice: How to properly remove a sprocket from a chainsaw?

The chainsaw requires regular diagnostics and periodic replacement of worn parts. With regular use, not only the saw headset becomes unusable, but also the drive sprocket. In this tool, it acts as a clutch disc, which is why it has a significant load both during start-up and during operation. The asterisk on the chainsaw has a simple design, so repairs and maintenance are easy to do with your own hands. In this article, we will look at how to determine the degree of wear of this part and carry out a planned replacement.

The performance of the tool will be determined by the way the chain-sprocket pair is operated. In most cases, users use one of two options:

  • The chain is operated until the teeth are completely worn out, and then both the saw blade and the sprocket are replaced at the same time;
  • Periodic replacement of chains with different pitch, and each will require its own drive sprocket.

The choice of option is often determined by the owner’s attitude to his instrument. If it doesn’t matter what to cut (wood or steel staples stuck in it, screws, etc.), then you can stop at the first option. The chain, however, will have to be adjusted periodically, thereby reducing the performance of the chainsaw.

It is strongly not recommended to leave the old chain with a new sprocket and vice versa. When the saw blade is worn out, the probability that the tooth pitch will not match is almost one hundred percent. Therefore, at the initial moment of starting, both components of the chain drive will be subjected to significant dynamic loads. As a result, either the chain will stretch prematurely, “adjusting” to the sprocket, or upon impact, one of the teeth on the drive sprocket will burst.

How to replace chainsaw drive sprocket/rim sprocket Husqvarna 359

In addition, it is worth focusing on the operation of the bearing assembly of the drive sprocket shaft. When the saw is operating at working speed, only the crankshaft rotates. But all chainsaws periodically operate at idle speed when the bearing rotates. With a lack of lubrication, the wear of the seat occurs, and. as a result. additional beating of the teeth of the still fully functional chain transmission.

It follows from this that when replacing the chain and the drive sprocket for a chainsaw, it is a good idea to replace the bearing at the same time.

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.

The design principle of the clutch drum at the unit

A chainsaw is a unit that is equipped with a drive sprocket and is a single complex with a clutch basket. Centrifugal-type clutches are installed on such units, which work automatically, based on how many revolutions the engine has.

The drums, which are the basis of such clutches on the machine mechanism, are considered integral parts of chain drive systems. Such details are similar in shape to a star, as a result of which they received such a name. Based on which chainsaw is being considered, these parts are divided into professional and household. Since professional chainsaws are used more often than household ones, the replacement of the drive sprocket in the tool should also occur more often. Considering household tools, it is worth noting that the frequency of replacement of parts is influenced by the amount of work performed and the loads that affect the unit chain.

But in any situation, the main reason for replacing the sprocket is the worn teeth, which are affected by the chain. If there is a monolithic drum in the device, the chain cuts through it practically through and through, and therefore it needs to be completely replaced. If drums with replaceable rims are installed in the units, then it is enough only to replace the rim itself.

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As a rule, if it is necessary to remove the sprocket from the chainsaw, many tool owners use the services of specialized service centers, but to save the family budget, such a replacement can be done independently. The implementation of this task is not difficult, but to complete it, you need the right parts and tools. Replacing the sprocket for each model of the chainsaw is carried out in the same way.

Sequence of work carried out

In the process of carrying out repair work, it is necessary to adhere to the following actions:

  • First of all, the saw headset is removed; a universal wrench is used to unscrew the nuts on the tire cover. The cover is removed, after which the tire and chain are removed.
  • The air filter is being removed.
  • Using the universal key, unscrew the candle of the device. In its place, a piston stop is temporarily installed, thanks to which it is possible to perform piston fixation of the piston in the cylinder.
  • The puller is installed in the socket on the universal key. After that, the resulting device allows you to freely unscrew the clutch. All actions are performed clockwise.
  • We remove the clutch, this will free up access for working with internal parts. Next, the sprocket is removed (clutch drum).
  • Based on what type of drum is installed in the unit, we inspect it and check the crown. We are replacing the sprocket or crown with a new part. When replacing them, it is imperative to check the condition of the clutch in the separator. Especially carefully check the springs in the centrifugal mechanism and the cams. If severe wear is found, then these parts must also be replaced.
  • In the case of a satisfactory condition of these elements, all parts of the chainsaw are assembled in the reverse order. Initially, it is necessary to unscrew the piston stopper, pull out the starter cord, and screw the stopper back in. Thanks to such complex actions, it is possible to clamp the centrifugal mechanism on the crankshaft.
  • Using the universal key, it is necessary to tighten the clutch counterclockwise.
  • After completing these steps, you can continue screwing the rest of the parts to their original place.

In order to replace the sprocket on a chainsaw correctly and without defects, it is necessary to do all the work in a high-quality and accurate manner. If you do not have special tools for repair work, then the process of replacing the drum may fail, since there is a possibility of breakage not only of the star or centrifugal mechanism, but also of the saw chain.

The above information gives a clear idea of ​​how to remove the sprocket from the saw. Thanks to this, no difficulties should arise and the task can be successfully completed absolutely independently. Having carried out such an operation at least once, you can repeat it without any problems when the need arises. For a clearer understanding of this procedure, we recommend watching a video on parsing a chainsaw and removing an asterisk.

How to replace the clutch drum

To replace the clutch drum, it is necessary to use only a certain type of structural element of this equipment. Along with this, the bearing of the structural element must be replaced at the same time.

To carry out repair work, you must use a special repair kit, which includes a drive sprocket and a bearing. Having purchased a repair kit, it is necessary to prepare the required materials and tools. Among the main tools that will be needed to carry out repairs, it is necessary to have:

  • universal key (provided in the complete set for the chainsaw);
  • piston stopper, can be either plastic or metal;
  • special puller for the centrifugal mechanism or the clutch drum.

Carrying out such work involves certain stages. When performing each of them, it is necessary to take into account the design features of a particular gasoline saw. But at the same time, the principle and method of this process is the same for all models of units.

Clutch repair: the nuances of the process

When servicing clutches yourself, you need to know that:

  • several saws have a washer that sits between the sprocket and the clutch and the sprocket and the motor. Consider this when repairing;
  • the special spring of the oil pump drive must not be damaged during disassembly, and must also be returned to its original position. Otherwise, the chain will receive less lubrication or no longer lubricate at all.

The tool that has been repaired must be checked for the reliability of the bolt ties, the supply of lubricant to the chain and the serviceability of the motor (it must turn on smoothly and work smoothly). Only then can it be exploited.


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.

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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.

The chainsaw guy shop talk Partner chainsaw parts saw.AVI

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

What you need to know about the design of the drive gears for chainsaws

The operation of the chainsaw can last long enough until there is a need to replace the failed parts. The drive sprocket or gear, through which the torque is transferred from the crankshaft to the chain, has a long service life. However, it also ends, which leads to the need to replace the part. Before doing this, it will be useful to learn about what chainsaw sprockets are.

Prefabricated and one-piece sprockets

Disassembly of Partner 351 chainsaw for spare parts Бензопила Партнер 351 на запчасти

Drive gears are available in two types. one-piece or one-piece with a drum and assembled. The difference between these parts is not only in the external design, but also in the operational features, which will certainly be interesting for owners of chainsaws to learn about.

If it becomes necessary to replace the drive sprocket on the chainsaw, then the first step is to clarify what type of part is installed on the tool. Manufacturers of different models of chainsaws equip them with drive gears of both modular and solid types. How they differ from each other is already known. One has only to add the following:

  • both types of parts are interchangeable, only the replacement is carried out in conjunction with the drive drum;
  • in terms of reliability, prefabricated devices win, by means of which an effective connection with the tool chain is ensured;
  • in addition to reliability, modular types are distinguished by the smooth running of the chain, which is achieved due to the presence of a backlash between the projection with slots on the drum and the crown;
  • due to the presence of backlash, the service life of the protrusions on the drum increases, but at the same time the entire load falls on the replaceable crown.

Prefabricated devices are noisy compared to solid ones, but they are also more efficient. It often happens that it is not possible to find a replacement ring for the chainsaw sprocket, which leads to the need to install a solid drum.

Interesting to know! The drum on a chainsaw practically does not wear out, so the use of solid sprockets to drive the chain in motion is irrational.

Algorithm for replacing the clutch drum

For trouble-free use of the chainsaw, regular technical inspection is necessary.

When replacing the clutch drum, only a strictly defined type of structural element of the device should be used for installation. When replacing the drum, the bearings of the structural element should be changed at the same time.

To carry out repair work, you should purchase a special repair kit, which includes a drive sprocket and a bearing. After purchasing a repair kit, prepare the materials and tools required for the repair. The main tools that will be required when carrying out repairs are the following:

  • universal wrench that comes with the chainsaw;
  • piston stopper, can be made of plastic or metal;
  • special puller of the centrifugal mechanism or clutch drum.

The work procedure consists of several stages. Each stage has its own characteristics depending on the design features of the chainsaw, but the scheme and sequence of work is the same for any model of the unit.

Algorithm for self-replacement of a sprocket on a chainsaw

The process of changing the chain drive mechanism on the tool is not difficult, and even a beginner can handle the task

It is important to take into account some of the features that you will learn about in this section. Due to the fact that the stars on the units are solid and prefabricated, then the procedure for replacing them will accordingly differ

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How an asterisk is removed and changed on a chainsaw

Before removing and replacing the star on the chainsaw, you need to make sure that the part is not subject to further use. To do this, you need to inspect the part, and a photo of a new and worn chainsaw sprocket is shown in the photo below.

To change the gear, you need to decide what type of device is on the tool, and what will be installed. For each type of mechanism, the sequence of actions will be different. Replacing an asterisk on a chainsaw of the first version of the non-separable type is as follows:

How to remove the protective cover on a gasoline tool

Removing the retaining ring, and behind it the washers

  • The gear wheel is dismantled together with the drum mechanism. The condition of the product is assessed. The presence of defects indicates the need to replace it.
  • The roller-type bearing is removed, which is also best replaced if there are signs of wear. If the condition of the bearing is satisfactory, it can be lubricated and reinstalled. When installing a new bearing, it must also be thoroughly lubricated with Litol-24 type lubricant.
  • Instead of a non-separable device, a prefabricated mechanism can be installed. This will subsequently simplify the process of replacing the drive gear.
  • The assembly process of the mechanism is carried out in the reverse order. If you need to replace a collapsible type product, then the process will be almost the same, only in the end one crown without a drum is replaced.

    Structural differences between one-piece and collapsible gears

    If the replacement process is completed, you need to check. The tension force of the chain is checked, for which the hand brake is turned on, and the chain is pulled in the direction of its movement. The immobility of the product indicates the constriction of the mount. To loosen it, you will need to release the tensioner.

    It is interesting! When replacing the mechanism in question, it is recommended to buy a special suitable repair kit for a specific tool model, depending on the chain pitch.

    Chainsaw clutch malfunction symptoms

    The centrifugal clutch of the chainsaw works until one of its standard elements fails. The following signs will tell the operator about a breakdown of the mechanism:

    constant rotation of the chain with unstable operation of the power unit. the main reason for this breakdown is a broken steel spring. To solve the problem, you will need to replace the chainsaw clutch spring.

    It is important to take into account the design features of the mechanism. For example, STIHL chainsaws have 3 springs and the same number of cams, while Husqvarna models have only 1 spring and 2 cams.

    If the operator cannot find a new spring, then the entire mechanism will need to be replaced; constant rotation of the chain with the formation of extraneous sounds from the clutch side. this occurs when the spring has flown off and the cam overheats or is damaged. To find the cause of the breakdown, you need to disassemble the clutch. If the cams turn blue, then they are overheated. This is due to constant work with the chainsaw with the inertial brake engaged or as a result of using a tool with a blunt cutting chain. To eliminate the breakdown, you will need to completely replace the clutch; frequent clutch slippage. the cause of the breakdown is a bursting metal spring. To repair the gasoline tool, you will need to replace the entire mechanism.

    In each of these cases, it is necessary to disassemble the clutch and inspect all its internal parts. In addition to replacing defective elements, the operator will also need to thoroughly clean the mechanism from dust and small sawdust. this will extend the service life of the remaining elements of the factory clutch.

    remove, asterisk, partner, chainsaw

    Main malfunctions, their causes and remedies:

    • If the chain mechanism constantly rotates during unstable operation of the power unit. This could be caused by a broken spring. In this case, it is recommended to replace the damaged mechanism with a new one.
    • During the movement of the chain, extraneous noise is heard. This problem could be due to overheating of the knuckle or a broken spring. It is necessary to conduct an external inspection of the system and replace all worn out elements.
    • If the breakdown is due to the fact that the hitch often slips, you need to completely replace the mechanism.

    Additionally: What brand of chainsaw to choose: production of good models in Europe, Asia and Russia