Replacing The Drive Sprocket On A Chainsaw

Table of Contents:

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 a 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.

About replacing an asterisk on a chainsaw:

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 localized both outside the chainsaw and on the 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.

Why replace the asterisk?

You need to remove a worn sprocket for the following reasons:

  • With the old sprocket, the saw chain will stretch very quickly. after a few uses, the chain will hang, and tension will not help;
  • If you put a new chain on an old sprocket, the smoothness of the chain will decrease, the quality of the cut will deteriorate, the chain will lead to the side when cutting;
  • The general wear of the chainsaw will accelerate, the tool may fail at any time;
  • The chain may break or the chain will jam during operation (it is dangerous with hand injuries and damage to the saw body, chainsaw);
  • The tire will heat up faster, which will lead to rapid overheating of the chainsaw;
  • The load on the engine and housing will increase.

How to change the sprocket on a chainsaw:

Leading sprockets for chainsaws, their types and design

There are two types of chain saw sprockets. prefabricated and solid. One-piece is a monolithic element installed behind the clutch. the so-called sprocket with a stationary ring. The crown is fixedly attached to the clutch drum connected to the centrifugal clutch.

A similar design is used in most chainsaws, including those made in China. There is nothing complicated in how to remove an asterisk from a Chinese chainsaw, no. but you need to completely remove the entire asterisk.

With more expensive models, the situation is even easier. Their chain saw sprockets have a modular design with a replaceable crown. The crown is put on the drum shaft and transmits the torque to the chain. Therefore, replacing the sprocket on a chainsaw is very quick and easy. the crown is removed, and the drum can be left in place.

Sequence of operations for replacing the sprocket

In the process of repairing any working unit of the chainsaw, you can change the rejected part only for a similar one. Experienced craftsmen purchase the necessary parts in advance.

To open and repair a chainsaw, you will need:

  • Allen wrench sold with the saw;
  • Piston lock, which can be replaced with a dense cord 6-8 mm thick;
  • Special puller.

An example would be a Husqvarna 137, a Japanese or Chinese chainsaw with a sprocket behind the clutch. First, remove the clutch cover. To do this, you will have to unscrew two nuts with a universal wrench. The guide bar and chain are then easily dismantled.

  • The air filter is removed;
  • The spark plug is removed to provide access to the engine cylinder;
  • By rotating the shaft clockwise, the cylinder piston rises to a vertical position, after which it is pulled back a few millimeters;
  • The inner space of the cylinder above the piston is filled with a tight cord to accurately fix the piston, and with it the crankshaft.

After securing the crankshaft, the puller is inserted into the holes of the coupling and rotated clockwise until it is completely dismantled.

A sprocket and a needle bearing are found behind the clutch, ensuring smooth rotation. If unacceptable wear is detected, they should be replaced with new ones. Revision and repair of the clutch consists in the inspection and replacement of springs and cams.

All parts are installed in reverse order. At the same time, to install the clutch, you will also have to fix the piston, but this must be done with left rotation of the crankshaft a few millimeters before the top point.

Chainsaw clutch system device

Chainsaws from Husqvarna, Stihl, Partner and most models of other well-known brands are equipped with a centrifugal clutch. It turns on automatically when the engine sets a certain speed.

The clutch basket is disc-shaped. It has movable friction pads that can move radially. In the normal state, they are pressed by the built-in springs to the center, without touching the drum of the driving sprocket of the chain drive.

Such a system is able to protect the engine from serious damage in the event of a chain jam.

Alternative solutions

The sequence of working moments is identical for almost all known models on the domestic market for chainsaw technology. Experts advise using a branded part to replace.

If we are talking about the modernization of this unit, the advisability of such a change should be clarified by consulting an experienced specialist.

The best option is to buy a repair kit, which also includes a replacement bearing. In addition to the key, you may need an individual clutch drum puller for each model, a metal or plastic stopper to fix the piston in a given position.

Method for a star with a collapsible clutch drum

The second method, regarding how to unscrew the sprocket on a chainsaw with a collapsible clutch drum, looks simplified compared to the previous one. The sequence of actions will be similar, but not the entire star will be subject to disassembly and reinstallation, but only a separate part of it. a gear ring.

Do not forget that installing a new chain on the chainsaw tire is one of the reasons to re-equip the saw with a new sprocket. Otherwise, the chain will stretch ahead of time or break during operation.

Less wear on the clutch drum gives the alternating use of several chains and periodic maintenance of its bearing. This mechanism is used exclusively at idle: when the speed rises, it is not involved in work.

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Experts recommend changing it along with the chain and sprocket and systematically lubricating it with chain oil.

How to Remove the Drive Sprocket From a Chainsaw

Replacing The Drive Sprocket On A Chainsaw

Chainsaw Leading Sprocket. Interesting with a step by step analysis of the chainsaw. Like any you need to remove from. Correct selection and substitution

The chain drive of a chainsaw of any design determines the performance of the tool. over, in the process of use, the chain is stretched, and the teeth of the drive sprocket wear out. An illiterate selection of an asterisk will drastically reduce the durability of the chainsaw teeth, and its improper adjustment will lead to early wear.

How to determine the need to replace a chainsaw sprocket

Chainsaw consumables include not only chains and tires, but also drive gears. Their resource corresponds to the service life of the chain, that is, it is recommended to change them after the cutting attachment is worn out. However, one should not focus on this, since everything depends on the features of the operation of the tool. If you saw with a chainsaw with blunt teeth, then after a couple of hours not only tire wear will occur, but also the tool sprockets.

The need to replace the guide sprocket on a chainsaw is determined visually. If there is a modular gear on the tool, then you can work with it until it is destroyed. The wear of the grooves on the crown occurs very slowly, due to the presence of backlash. If a solid star is installed on the unit, then you can determine the need for its replacement by a number of the following signs:

  • The presence of noticeable radii in places between the teeth.
  • Tooth tips show clear metal chipping.
  • Uneven tooth width.
  • The presence of scuffs and chips inside the hub bore, which is a sign of poor lubrication of the mechanism.

If you strive to always maintain the tool in good condition, it is recommended to change the sprocket together with the chain.

Algorithm for self-replacement of a sprocket on a chainsaw

Changing the chain drive mechanism on the tool is not difficult, and even a beginner can handle the task. It is important to consider 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.

How to replace a sprocket with a replaceable crown

If your chainsaw is equipped with an assembled type drive gear, then only the crown must be replaced. It is inexpensive, and before buying it, you need to clarify the chain pitch. The process of installing a new part is carried out in the following sequence:

  • Remove the cover by unscrewing the two nuts.
  • Dismantle the bar together with the chain, having previously released the tension of the headset.
  • Remove the plastic cover followed by dismantling the air filter.
  • Unscrew the spark plug to stop the piston.
  • Insert a dense and strong rope into the cylinder bore, having previously moved the piston to TDC. With the help of a rope, the crankshaft is locked, which is performed to unscrew the clutch on the chainsaw.
  • Next, we proceed to unscrew the clutch, which will require a special wrench. If such a key is not supplied with the chainsaw, then a regular open-end key will do. However, it is best to use an angle grinder wrench, which is ideal for unscrewing the coupling.
  • To unscrew the clutch, turn it clockwise.
  • After unscrewing the coupling, it remains to dismantle the drum along with the crown.
  • Inspect the integrity of the bearing, which is mounted on the shaft. If necessary, it is also recommended to replace and lubricate it.
  • Replace the replaceable ring, and assemble the mechanism in the reverse order of removal.

The above instructions are for removing the clutch on a chainsaw to replace the drive sprocket. The change of one-piece device is carried out in the same way. This type of part arrangement is called internal. To replace it, it is necessary to dismantle the coupling. If the chainsaw has a single piece with an external location, then the change process will be different.

What you need to know about the design of the drive gears on 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, by means of which the torque is transmitted 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 know what chainsaw sprockets are.

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

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 various 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 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 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 noisier than 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.

Replacing the drive sprocket on the chainsaw according to the instructions. when to do and what to install

The use of any tool contributes to the wear of parts. The chainsaw is no exception, and often the owners of this tool are faced with the need to replace the drive sprocket. It is a device for transmitting torque from the crankshaft of the internal combustion engine to the chain. Before replacing the asterisk on the chainsaw, which every tool owner can handle, you need to competently approach the issue of choice.

How to replace a solid outer sprocket

The process of replacing an external sprocket is carried out in the following sequence:

  • To remove the external gear, you need to dismantle the protective casing by unscrewing two nuts.
  • Remove the chain and bar by relieving tension.
  • Clean tool from dirt.
  • Remove the retaining ring with a screwdriver.
  • There is a washer under the ring that prevents the chain from displacement when it rotates.
  • Remove the drum and replace it.
  • The assembly process is carried out in reverse order.

The process of replacing external sprockets is much faster and easier, since there is no need to lock the engine crankshaft.

After finishing work, set the chain tension. As you can see, it is not at all necessary to hand over the chainsaw for repair when it becomes necessary to replace the chain drive mechanism.

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 a 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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About replacing an asterisk on a chainsaw:

A little about the rules for operating the node

Regardless of the manufacturer’s brand (Stihl, Husqvarna, Partner, Patriot, Makita), chainsaws are divided into household, semi-professional and professional. The difference, however, is not the quality of the assembly or the manufacture of the components, but the class of tasks performed, the performance and the continuous power of the drive. This predetermines the choice of the material of the leading sprocket for the chainsaw, its design and the design of the saw chain.

The performance of the tool will depend on how 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’s all the same what to cut (wood or steel staples, screws, etc. stuck in it), 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.

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.

From this it follows 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.

Stihl chainsaw repair. Replacing the drive sprocket

Today we will briefly dwell on one of the most common malfunctions of the Stihl chainsaw. wear or breakage of the chain sprocket. It should be noted that this topic is familiar to almost any professional, and our publication is unlikely to seem interesting. First of all, we appeal to amateurs, summer residents, gardeners, people involved in landscaping. Below we will talk about what a chain sprocket is, what is its role in the mechanism of a chainsaw, how to replace it and give general recommendations for operation.

Chainsaw repair in the Direct Hands service center.

In case you find a malfunction of the chainsaw or simply doubt the performance of the tool, please contact our workshop. We are a dealer and official service of Stihl in St. Petersburg and the Leningrad region. Our experts will make for you warranty and post-warranty repairs of the Stihl chainsaw.

About replacing the sprocket on a chainsaw or saw

Recommendations for the correct use of the chain sprocket

During the operation of the chainsaw, it is necessary to regularly check the wear (running-in) of the sprocket. If the running-in depth exceeds 0.5 mm, the part must be replaced. Operating the tool with a worn sprocket will result in faster chain wear. Chainsaw manufacturer Stihl recommends replacing the sprocket after two chains are worn. It is also recommended to use not one chain, but two or three alternately. The load on the drive sprocket can be reduced by using a high-quality chain and stable operation of the lubrication mechanism. For quality lubrication of the saw headset, use original guide rails and Stihl greases.

Features of the operation of the chainsaw

The gasoline saw is a classic mechanism driven by an internal combustion engine. The tool design device provides for the use of the simplest single-cylinder two-stroke carburetor engine running on a gasoline basis. Due to the simplicity of such engines and the design features of a gasoline saw, this unit is a reliable and reliable device that can withstand harsh operating conditions.

When working with a chainsaw, the operator does not require special knowledge or skills. The only condition for long-term and trouble-free operation of the equipment is regular technical inspection and maintenance of the tool. When using the device, it is necessary to replace worn-out parts on a regular basis. To reduce wear on the attachment, it is necessary to carefully monitor that the saw chain is well lubricated, control the degree of wear of the chain itself and the drive sprocket.

Before repairing a gasoline saw, you should understand in detail its design. To replace any main structural element, for example, a drive sprocket, it is necessary to familiarize yourself with the interaction mechanism of the clutches on the unit.

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. In addition, the bearing of the structural element must be replaced simultaneously.

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 for repairs, the presence of:

  • Universal key (provided for chainsaw);
  • Piston stopper, can be either plastic or metal;
  • Special puller for centrifugal mechanism or 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.

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

How to replace the drive sprocket on a saw or chainsaw. more on this in detail.

For the sprocket replacement procedure, 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 by removing debris and sawdust from the mounting holes;
  • 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 starts to rotate and do this until the piston touches the outlet;
  • After that, the stopper or lace is lowered into the candle opening and fixed there, tying several knots (the stopper will fix itself);
  • We 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;
  • Next, the clutch is removed;
  • After the sprocket gear itself is removed;
  • Replace the old sprocket with a new one;
  • The assembly of the structure is carried out in the reverse order.

How to assemble?

The assembly of the coupling mechanism should be carried out in the reverse order. First, install the sprocket on the needle bearing, then put on the drum, washer, gasket and the coupling itself. Tighten counterclockwise, lightly fix the piston.

If your chainsaw has an oil drive spring, it can be built into the drive sprocket. In most models, the correct position of this element is marked with a special color or notch. To get to the desired position, turn the sprocket until it clicks.

The last step in the assembly is to install the guide bar. During this process, it is required to release the handbrake and then check that the chain teeth fit into the corresponding grooves. After installation, mount the chainsaw chain to working condition. At the end, remove the stopper, screw in the spark plug and replace the filter. The final step of the repair is to secure the protective cover of the case.

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How to unscrew?

It is not difficult to remove and replace this part yourself. Work technology:

  • Secure the piston in the saw cylinder. First, remove the protective cover on the body, the air filter and unscrew the spark plug. Install a special piston stopper in the hole formed. instead, you can use a dense nylon cord or wire up to 15 cm long.If the piston interferes, you can slightly turn the sprocket or move the chain clockwise.
  • Unscrew the bolts on the cover that secures the tire, remove the protective cover. Loosen the chain tension or remove the saw attachment. At the same time, you can clean from dust, dirt and sawdust.
  • Depending on the model, the sprocket acts as an element of the clutch drum or be built in separately. In the second option, remove this part, replace it with a new one. The one-piece structure is difficult to repair. you need to disassemble the unit. To do this, unscrew the coupling clockwise, remove the drum. Check structural parts for wear and deformation. Figure 4. Replacing the star with a new one

Features of star replacement for chainsaws of different brands

When replacing or repairing a chainsaw, the design features of the model should be taken into account. The specifics of servicing the coupling drum of popular manufacturers:

  • Stihl (Stihl). The models of this brand have one-piece and collapsible types of sprockets. To unwind the clutch, you need a 19 head and a knob. It should be noted that the thread is left-handed, and a reflective plate is installed behind the clutch (consumable material, often breaks during drum diagnostics).
  • Partner (Partner). The peculiarity of this brand is that when replacing the sprocket, it is recommended to change the bearing. If you ignore this step, after a planned repair, there is a risk of chain malfunction, changing the pitch during active sawing.
  • Husqvarna (Husqvarna). Many Husqvarna models use an interchangeable sprocket. This simplifies scheduled replacement and repairs. When disassembling the tool, you need a 13 wrench to fix the shaft from the impeller side.
  • Carver (Carver). Unlike other manufacturers, there are no specific design features of the clutch. Depending on the brand, the star can be solid or collapsible.

It is recommended that you carefully read the instructions before starting the scheduled repairs. It indicates the important design features of the saw, the frequency of replacing consumables.

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 factory pressing, the crown cannot be removed separately from the hub, therefore, in the event of a breakdown, it is necessary to disassemble the entire clutch drum. Such a mechanism is usually found on Chinese models.

How to change a star on a chainsaw?

If the chain begins to vibrate even at low speeds, the chainsaw is operated for a long time without replacing parts. it is required

Carry out diagnostics and, if necessary, change the components of the saw headset. For a planned replacement, you will need a new clutch drum or whisk, depending on the specific model, a basic set of tools:

  • Candle wrench;
  • Cable up to 15 cm long or piston stopper;
  • Factory key for removing the clutch;
  • Adjustable or wrench. Figure 3. Necessary tools for changing the star

It is recommended to have a round file, pliers, a vise and a knife to eliminate design flaws from the chain set (if only tooth correction is required).

The device of a leading star on a chainsaw

Almost all models of modern chainsaws use a centrifugal clutch system. The specificity of this mechanism is that when the maximum number of revolutions of the gasoline engine is reached, the clutch drum starts automatically, transferring the rotation to the drive sprocket. This reduces stress on the base parts of the tool, extending service life and maximizing productivity.

Figure 1. Diagram of the drive star device

The clutch drum, where the sprocket is located, can be located on the inside or outside of the chainsaw body. There is always a cover on top to protect moving mechanisms from dirt, sawdust and dust. The clutch itself is a metal disc in the clutch drum. The entire mechanism is attached to the engine crankshaft by bolts with springs, along the edges of which there are friction linings. When the engine rpm exceeds a certain value, centrifugal force is generated, exerting strong pressure on the inside of the drum. After that, the sprocket starts up. the rotation of the chain saw begins.

Expert advice: How to 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 sprocket 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.

When replacement is needed?

The saw head and drive sprocket are subject to natural wear and tear during operation. This is not a breakdown, but a routine tool maintenance procedure. Reasons for replacing the sprocket:

  • Intensive and long-term use of the saw;
  • Mechanical shock to the headset;
  • Using the wrong chain. Figure 2. Leading star on a chainsaw

Normal wear of the drive sprocket teeth is up to 0.5 mm. With regular work, this figure can reach up to 1 mm, but over time this will lead to a load on the engine, damage to other parts of the saw. You can determine the need for replacement or repair by the following signs:

  • There is mechanical damage to the guide sprocket;
  • The width of the teeth is not proportional to their height;
  • There are asymmetric angles;
  • Hub has chips, grooves, or large burrs.

If you do not timely diagnose and prevent the moving parts of the chainsaw, vibration increases and the impact on the crankshaft bearings increases. As a result, this leads to costly repairs, serious tool breakage.

How to reduce wear on the drive sprocket?

The service life of the chainsaw clutch can be increased by routine maintenance and high-quality tool maintenance. Helpful hints:

  • Apply grease to the needle bearing after each sprocket change;
  • Correctly select all parts of the saw headset, depending on the chain pitch, use reliable consumables;
  • Do not replace the clutch and saw parts at the same time. this leads to a change in pitch, wear of the headset;
  • Clean the saw regularly by removing the side cover.

Chainsaw sprocket replacement is a routine procedure that ensures reliable and stable tool operation. When diagnosing or repairing the coupling mechanism, one should take into account the design features of the model, the manufacturer’s requirements. To avoid frequent breakdowns, it is recommended to use only original parts or high-quality analogs, systematically clean the chainsaw.