How To Remove A Sprocket From A Saw
Why it is necessary to replace the drive sprocket
Among the most common reasons a tool may need to be repaired is the replacement of the drive sprocket. This part becomes unusable due to:
- Chain jamming in the event of any defect during the operation of the equipment;
- High wear of the sprocket with prolonged use of the chainsaw.
Regular use of the tool contributes to increased wear on the part due to the increased stress when sawing wood materials. There are several known ways to use the tool:
- By using one chain saw.
- By alternately using several chain saws.
With the first method of using the tool, the saw is operated until it is completely worn out. This method has certain disadvantages, among which a problem can be noted when carrying out manipulations that control wear as a result of intensive operational actions.
When working with two or more chains, you can get even wear on each chain and sprocket, which will significantly extend the operation of the unit and reduce the need for frequent drum changes. In addition, it is important to keep in mind the condition of the bearing in the drum. The work of this structural element occurs at any engine speed. When replacing a sprocket, it is also important to take care of replacing the bearing and coupling.
Untimely repairs contribute to the occurrence of increased vibration, which affects the increase in wear rates of parts that are installed in the engine of the device on the crankshaft axle shaft. The value of the limiting depth when the teeth of the sprockets are worn should not be more than 0.5 mm. Sprockets have twice the lifespan of chains. Therefore, it is recommended to use two chains.
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 considered, these parts are divided into professional and household. Since professional chainsaws are used more often than household ones, the drive sprocket in the tool should be replaced more often. Considering household tools, it is worth noting that the frequency of replacement of parts is affected 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 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.
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 chainsaw is carried out in the same way.
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.
“Removing the clutch from the chainsaw.” How to remove the drive sprocket from a chainsaw Husqvarna, Partner, Stihl, Champion
Regular use of many tools requires periodic replacement of 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 sequence of work
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. A piston stopper is temporarily installed in its place, 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 a standard universal wrench, 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 perform 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 you 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 performed 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 that you look at the parsing of the chainsaw and removing the asterisk.
Is it wise to try to fix or sharpen the star?
The cost of this spare part is small, and self-repair or an attempt to restore a worn part never leads to the efficient operation of the chainsaw. It is recommended to replace the part with a new one if there are signs of wear.
How to unscrew an asterisk on a chainsaw:
How to remove an asterisk from a chainsaw and replace it yourself
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:
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.
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.
Reasons for replacing the sprocket
Replacing the sprocket on a chainsaw with opening and revising the entire clutch unit is carried out in the following cases:
- Jammed chain movement;
- Physical wear of the sprocket to unacceptable limits.
The deviation of the geometric dimensions of the sprocket teeth from the nominal should not exceed 0.5 mm. Otherwise, the saw operation will be accompanied by increased vibration, which will lead to premature failure of the crankshaft bearings or the entire tool.
Typically, a sprocket has a lifespan of approximately double the lifespan of a single chain. In practice, 2-3 chains are often used alternately until their cutting edges wear out, after which they acquire a new set and change the sprocket.
Chainsaw sprocket replacement
Chainsaws produced by well-known manufacturers of special tools are characterized by high reliability and long service life. This is due to the thoughtfulness of the design and the use of special grades of tool steel, from which all moving and rubbing parts are made. These should primarily include:
- Chain with cutting edges;
- Guide tire;
- Chain sprocket driven in rotary motion by the energy of a single-cylinder two-stroke gasoline engine.
All of them work intensively and wear out over time. Even a slight change in the geometric dimensions of these parts degrades the performance and smoothness of the saw. If you needed to remove the sprocket from the chainsaw in order to replace it, you need to understand the principle of the clutch system, with which it has a direct connection.
Structural problems of different models
The problem is complicated by the design of branded chainsaws, which provides for the replacement of a worn drive only after complete dismantling of the clutch mechanism and other components. Alternatively, in order to remove the sprocket from the chainsaw, you must have a special key.
A design feature of a significant part of chainsaw imports is the placement of a sprocket on the clutch mechanism.
- In case of significant wear of the teeth, the drum must be replaced, which is integral with the drive.
- A more progressive design of the drive sprocket allows you to restore the performance of the part by replacing the crown.
In the list of factory sets supplied with saws, such a tool is extremely rare. The problem is solved by replacing the worn-out part in a service workshop or by making the necessary device at home.
Algorithm for self-replacement of the clutch drum with an asterisk
The technology of replacing the leading sprocket provides for the implementation of the entire amount of work in a given sequence:
- Dismantling the headset and air filter;
- Installation of a piston retainer in the spark plug hole;
- The clutch and the gear drive, made at the same time with the drum, are removed by means of a puller, the sprocket can be unscrewed only clockwise.
If a large cage wear is detected, the centrifugal mechanism springs and cams are broken, it is recommended to replace the entire set.
If the condition of the removed parts is not in doubt, the entire mechanism is assembled in reverse order. To securely fix the clutch on the crankshaft, just unscrew the piston stopper, pull out the standard starter cord and return it to its original position.
Amateur craftsmen should be warned against simplifying the requirements of repair technology and saving money on installing relatively cheap Chinese components.
The quality of the work done is guaranteed by attention, accuracy, adherence to the sequence of all dismantling and assembly operations.
Saw designs feature
Professional chainsaw from STIHL
There are already several dozen chainsaws in operation from different manufacturers, capacities, and most importantly, 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 to eliminate them are described here.
How to remove an asterisk from a Husqvarna, Partner, Stihl chainsaw with your own hands
The movement of the chain along the tire of the chainsaw is carried out due to the drive sprocket connected to the engine gearbox.
The wear of the spline on the sprocket indicates that it needs to be replaced as soon as possible, otherwise the clutch with the chain will not occur, and the chain itself will be damaged.
It should be borne in mind that the drive sprocket has a number of features depending on the saw model and its type. In this article, we will highlight such a question as how to remove an asterisk from a chainsaw.
Chainsaw sprocket, crown and bearing
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, 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 access the bus 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.
- Rotating the sprocket manually, 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:
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.
How to remove an asterisk on a chainsaw
You can remove and change the asterisk at home without resorting to the services of a service center. The procedure is as follows:
- We unscrew the fastening of the saw headset with a special key;
- Unscrew and remove the headset cover;
- We unscrew and remove the air filter cover and the filter itself;
- Unscrew the spark plug.
To remove the sprocket, you need to fix the engine piston. To do this, we smoothly pull the kick starter cord, lifting the piston up, but not bringing it to the end. Push a long piece of thick cord into the candle hole until the space of the combustion chamber is filled. This is in order to prevent the piston from going past top dead center. At the same time, the cord will serve as a damper, protecting the piston from possible damage. Part of the cord should protrude from the hole so that it can be removed later.
To unscrew the sprocket, you need a special wrench, which rarely comes with saws, especially for cheap models. You need to use a drift made of soft metal. copper or aluminum.
The drift is leaned against the protrusions of the cams of the centrifugal mechanism and light blows are applied with a hammer. The direction of impact should be almost parallel to the plane of the clutch, because at a large angle, the cam mount can be bent and the clutch will have to be changed. The direction of impact is counterclockwise. Often the clutch is labeled “off” and an arrow indicating the direction of impact.
After loosening the nut from its place, you can unscrew it by hand.
Some saw manufacturers use simple left-hand nuts to attach the clutch and sprocket. Then the task is simplified, since for removal you can take a simple open-end wrench of the required size.
Now remove the drive sprocket, being careful not to lose the plastic oil pump drive gear and the needle bearing.
How to remove an asterisk from a chainsaw
Chainsaw drive parts are key and highly loaded. The performance and performance of the entire unit depends on them. During operation, they wear out. the chain lengthens, and the tire and the teeth of the drive sprocket wear out. The correct selection of replacement parts and accurate alignment will extend tool life and avoid increased wear and tear.
Unit clutch design
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 displacement of the elements with friction linings. These elements are pressed against the inner walls of the drum by centrifugal force. Due to this contact, the rotational movement is transmitted to the drum and 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.
How to independently remove the leading sprocket from a chainsaw and change to a new one
The chain saw sprocket is used to transmit engine torque through the centrifugal clutch to the saw chain. The sprocket teeth are subjected to heavy loads during operation and therefore gradually wear out. It is not difficult to remove the sprocket from the chainsaw using a special tool, but you can do the job with improvised means.
Causes of malfunction and how to determine the need for replacement
Drive sprocket teeth can be worn for several reasons:
- Normal wear and tear together in the chain teeth;
- Accelerated wear as a result of excessive tension or lack of lubrication of the chain;
- Incorrectly matched chain;
- Technological defect.
Metal wear can be determined visually when inspecting the sprocket without removing it from the saw. Dents and chips on the surface should not exceed 0.5 mm.
The need for replacement is determined by the increased noise when the chain moves, but this is typical only in the presence of deep potholes. It is difficult to notice a shallow development during operation, but the chain will wear out strongly. If the teeth are broken, the chain can move in jerks, which is especially well felt during operation.
How to remove a prefabricated sprocket from a chainsaw
Removing the collapsible gear occurs in the same sequence, except for the last operation. In its course, not the entire gear is removed, but only its crown.
To do this, release the brake and pull the blade in the direction of the working movement. If there is no play, then the chain is overtightened and should be loosened. If, however, it is possible to pull back so that the gap between the links and the tire is visible, the tension is insufficient and its
How to remove a drive sprocket from a chainsaw
Depending on the design features of the gear, the sequence of operations required to remove it differs.
Design features of leading sprockets
The tooth pitch of the drive gear is one of the main parameters of the assembly. It must match the pitch of the chain links and, just as important, the pitch of the teeth of the driven sprocket located at the end of the chainsaw bar.
According to their design features, the drive gears are divided into:
Experts identify the following signs of wear on the teeth of the drive gear:
- Semicircular depressions are visible at the base of the tooth;
- The thickness of the prong changes with height;
- Chipped areas at the top;
- There are scratches inside the hub hole;
- The chain has rubbed the sprocket groove;
- Chainsaw wedges when starting.
A chainsaw sprocket with such signs should not be used, it must be removed and replaced.
According to the manufacturer’s recommendations, the tool should be inspected before starting work. In this case, the condition of the saw bar is necessarily checked, whether it is securely fixed. If the screw regulating the position of the chain roller and its tension is loosened, or the nuts securing the bar to the body are loosened, it deviates from the plane of the chain. In this case, the blade rollers do not rest on the middle, but on the edges of the teeth, increasing the load on them and on the chainsaw as a whole. Increased wear leads to premature failure.
Sprockets with replaceable and stationary crown
After tightening the fasteners and adjustments, a test run is made. If free play remains, then the sprocket will have to be removed and replaced.