Regardless of complexity, tasks and frequency of use, all tools require periodic maintenance or repair. Chainsaws are no exception, despite their thoughtful design and performance characteristics. But, like all equipment with moving parts, chainsaws are subject to wear and tear and require periodic inspection. And first of all, such parts include the saw chain, to extend the service life of which, timely replacement of the sprocket is important. This is exactly what we will talk about in this article.
Chainsaw drive sprocket device
An asterisk or centrifugal mechanism is a part shaped like a star.
It takes on the engine torque and transmits it to the guide and saw chain. This guarantees the rotation of the cutting set and the sawing process itself. It operates automatically, which depends on the amount of engine speed. The clutch drum can be located both outside the chainsaw and on its inside - under a separate cover. It performs a protective function not only in relation to the material from which the sprocket is made, but also for the operator, who may be injured by it during work. In addition to the function of chain rotation, the saw drive star prevents the occurrence of malfunctions of the motor system in cases where the chain jams or stops rotating.
The owner’s desire to equip the headset with a saw chain with a different pitch leads to the need to replace the sprocket with a part with a crown of the corresponding profile. This requirement applies to the entire range of chainsaws made in Europe and China.
The operational reliability of a European-assembled saw, when working under difficult conditions with increased loads, can significantly deteriorate if a Chinese-made sprocket is installed instead of a branded part.
Types of stars
Depending on the class of the chainsaw, all stars are divided into two groups. professional and household. Parts of the first type have increased wear resistance and are made of durable metal alloys that are resistant to corrosion and mechanical damage. Households often require replacement and routine repairs; When actively using the tool, diagnostics are recommended every six months. Based on their design features, the following types of stars can be distinguished:
- Prefabricated . The removable ring can be easily unscrewed from the drum axis making it easy to check and replace this part. Almost all European chainsaw models are equipped with such stars.
- goals . They consist of a hub and a fixed crown (the number of teeth may vary; you need to carefully read the instructions for the chainsaw). Through factory pressing, the crown cannot be removed separately from the hub, so in the event of a breakdown, the entire clutch drum must be disassembled. This mechanism is usually found on Chinese models.
Replacing the drive sprocket on Husqvarna 154, 254, 262 chainsaws
For Husqvarna chainsaw models 154, 254, 262 series
, equipped with
8-tooth
chains with
a 0.325
a Rezer SP 38071
drive sprocket is used .
The part differs from the previous all-metal construction
. This means that there is no such element as a replaceable crown.
On the one hand, such a detail loses
in operational life, on the other hand, it has a more
attractive cost
.
The price is almost two times lower
compared to sprockets with a replaceable crown.
Husqvarna 154, 254, 262
models by clicking on the following link.
Drive sprocket replacement process for Husqvarna 154, 254, 262
has a slightly different algorithm. Let's look at it in more detail.
Remove the side of the chainsaw to gain access to the saw group
.
Using a combination key
loosen
the chain
and remove it together with
the bar
.
Remove the rope starter
from the opposite side.
Use hex wrenches
.
Fix the shaft on the impeller side with a 13mm wrench
.
Using a special key
remove
the clutch
.
Unscrewing should be done clockwise
.
Dismantle
sprocket and needle bearing.
Assembly is carried out in reverse order
.
The clutch should be tightened counterclockwise
.
The force should not be too high
, since the coupling
self-tightens
when rotating.
In fact, the replacement process is not very difficult.
and it is quite possible to produce it
yourself
.
Buy quality drive sprockets
for
Husqvarna 154, 254, 262
in our TUKINGARDEN store.
Reasons for replacement
Let's consider in what cases it is necessary to replace the drive sprocket:
- Physical wear and tear to unacceptable levels. Leads to chain flying and slipping, reduces smooth running, and reduces work productivity;
- Chain jamming. With such a malfunction, no work is possible, moreover, it is dangerous;
Chainsaw chain maintenance
- The owner's desire to use a new chain. Running a new chain on an old sprocket increases the risk of creating a hazardous situation and can lead to chain breakage;
If you want to extend the life of the drive sprocket, we recommend purchasing two chains and using them alternately. This will balance the production of parts and will not create additional loads on them.
Replacing the clutch drum with sprocket
All modern chainsaws are equipped with a chain brake device and in most models its operation is carried out by means of a belt located on the tire cover and a chain that goes around the clutch drum.
When the chain brake is engaged and the gas trigger is pressed, the clutch disc continues to rotate, and the drum is clamped by the brake band. If you do not turn off the brake in time and continue to press the gas trigger, the tire cover and chains will begin to melt, and the clutch drum may burst.
To replace the clutch drum you must:
- Remove the air filter cover;
- Stop the engine and unscrew the nuts;
- Pull out the clutch disc;
- Stop the engine;
- Install the new disc, press the washer and nut.
Types of stars
Depending on the class of chainsaw, all stars are divided into two groups. professional and household. Parts of the first type have high wear resistance and are made of strong iron alloys that are resistant to corrosion and mechanical damage. Households often require replacement and routine repairs; When actively using the tool, diagnostics are recommended every six months. Based on their design features, the following types of stars can be distinguished:
- Prefabricated . The removable ring can be easily unscrewed from the drum axis making it easy to check and replace this part. Almost all European chainsaw models are equipped with such stars.
- goals . They consist of a hub and a fixed crown (the number of teeth may vary; you need to carefully read the instructions for the chainsaw). Through factory pressing, the crown cannot be removed separately from the hub, so in the event of a breakdown, the entire clutch drum must be disassembled. This mechanism is usually found on Chinese models.
How to assemble?
Reassembling the clutch mechanism must be done in the reverse order. First install the sprocket onto the needle bearing, then put on the drum, washer, gasket and the clutch itself. Tighten counterclockwise, locking the piston slightly.
If your chainsaw has an oil-driven spring, it can be built into the drive sprocket. In most models, the correct location of this element is indicated by a special color or cutout. To get to the desired position, turn the sprocket until it clicks.
The last stage of assembly. installation of the guide rod. During this process, you need to release the handbrake and then check that the chain teeth are inserted into the corresponding grooves. After installation, install the chainsaw chain to working condition. Finally, remove the plug, screw in the spark plug and replace the filter. The final stage of repair is to secure the protective coating of the housing.
Drive sprocket for chainsaw
A chainsaw sprocket or clutch plate serves to transmit rotational motion and power to the saw chain. Structurally, there are three types of drive sprockets;
1. The sprocket is solid. In such a sprocket, the clutch plate is rigidly welded to the drive ring. In case of wear, the entire sprocket is replaced.
2. The sprocket is collapsible. It is a clutch plate with splines onto which the crown drive sprocket fits. The clutch plate wears out very little and a replacement hub is cheap. The collapsible sprocket is very beneficial for large volumes of work and is used mainly by professionals.
3. The sprocket is a replaceable crown. This sprocket is used to replace on collapsible sprockets.
The selection of the drive sprocket is carried out according to the chainsaw model. If you are in doubt about your choice, call us and we will try to suggest the correct spare part.
Removal and replacement process
In the first case, the removal process is somewhat simpler. To do this, you just need to pull off the retaining ring with a screwdriver, after which the sprocket can be easily removed.
In the second case, you will first have to remove the clutch. To do this, you need to lock the shaft on which it is located. This can be done in two ways:
- Or unscrew the spark plug and screw in a special piston stopper instead, which would prevent the latter from moving.
- Or, from the starter side, insert a suitable key or screwdriver into one of the existing holes to lock the impeller there. However, this method is dangerous because often the sprocket is tightened quite tightly, which is why it is more likely to break the impeller blades than to unscrew the star. Therefore, if you do not have a stopper from the previous method, then use the traditional method from the next point.
- The popular method is that, instead of a special stopper, you can push a piece of fabric into the combustion chamber through the hole where the candle is wrapped, leaving part of it outside so that you can later pull it out. The fabric will occupy all the space inside and will not allow the piston to move upward, which will cause the shaft to stall. Moreover, due to the fact that the fabric itself is soft, it will not cause any damage to the walls of the cylinder.
Once the shaft is locked, you can unscrew the clutch. You need to use either a special puller, or you can get by with a suitable open-end wrench by inserting it into the recesses on the clutch. Unscrewing is done clockwise, since the thread on the shaft is left-handed.
Having unscrewed the clutch, you can now easily remove the sprocket.
Installation of new spare parts must be done in reverse order.
As you can see, it’s nothing complicated—everyone can do it.
How to change a sprocket on a chainsaw?
To replace a worn element, you will need to buy a part of the same type and with the same dimensions as the standard element. In most cases, the factory chainsaw bearing must also be replaced during repairs.
It is best to initially buy a repair kit, which includes both a bearing and a sprocket. To remove the sprocket from the chainsaw and install a new part in its place, you will also need to prepare tools. Their list includes:
- a universal key, which is supplied with the chainsaw;
- removable key for dismantling the centrifugal clutch. When choosing it, you need to take into account the model of the chainsaw;
- mechanical piston stopper. A metal or plastic tool is suitable for removing the piston.
Replacing the sprocket on the chainsaw tire should be done in the following order:
- First, you will need to remove the saw blade assembly. Using a universal key, you need to unscrew the protective covers;
- Next, you need to remove the standard air filter of the instrument;
- After this, using a universal key, you will need to unscrew the spark plug. In its place, you need to install a mechanical piston stopper - it is necessary to fix the piston in a stationary position;
- Then you will need to install a removable key in the universal key slot to dismantle the clutch mechanism. Using the resulting device, you need to carefully dismantle the standard saw clutch. To do this, the factory assembly should be turned clockwise;
- After removing the coupling, passage to the internal elements is free. This will make it possible to unscrew the sprocket of the household chainsaw;
- The removed drum will need to be carefully inspected. If necessary, the ring or sprocket should be replaced. During replacement, you will need to check the separator. If necessary, you need to replace worn springs and cams of the centrifugal mechanism;
- After replacing all faulty elements, you can begin reassembling the chainsaw. To do this, you first need to unscrew the previously installed piston corkscrew, and also pull out the factory trigger cable. After this, the stopper will need to be screwed back in. This will make it possible to reliably press the centrifugal clutch of the tool onto the engine crankshaft;
- Next, using the universal key, you will need to press the clutch counterclockwise;
- At the end, all previously dismantled parts can be installed back on the chainsaw.
How to reduce wear of a part?
There are a number of rules by following which the owner of a chainsaw will be able to reduce the wear rate of the leading part of the garden tool. Their list includes:
- preventing the saw chain from getting on nails, stones and other hard objects. The less often the headset comes into contact with foreign objects, the less the load will affect the leading element of the instrument;
- use only high-quality lubricants. They have all the components necessary to maintain stable operation of the sprocket and cutting elements;
- correct conditions for storing the saw - in wet, damp rooms, the metal parts of the tool will succumb to rust. The sprocket also suffers from this, especially if it is not covered with a protective cover.
The weather conditions in which the garden tool is used also play an important role. Its owner needs to avoid frequent use of the saw in rainy weather. This will not only make it possible to protect the sprocket from rust, but will also make the work safer for the operator.
Types of clutch malfunctions and ways to eliminate them
Here the list of possible breakdowns is not so long, the most common cases are:
Damaged spring , it can be stretched or burst, in both cases the clutch will not work and repairs are necessary. Depending on the brand of chainsaw, you will have to replace the spring or the entire clutch. So, for example, on Stihl saws it is possible to replace the spring, but on Husqvarna and Echo you will have to completely change the clutch.
Clutch drum , on which the chainsaw drive sprocket is located. Wear of the drum and sprocket also impairs the performance of the clutch mechanism; it is determined quite simply; wear inside the drum and on the sprocket is visible to the naked eye. The problem can be eliminated by installing a new clutch drum.
Another type of failure is a faulty bearing inside the clutch drum; its wear is also natural, although not as frequent as compared to the cases described above. On many models of chainsaws, this bearing is replaced, and there is no need to change the entire clutch.
Features of replacing a star for chainsaws of different brands
When replacing or repairing a chainsaw, you should take into account the design features of the model. Specifics of servicing drum couplings from popular manufacturers:
- Stihl (Stihl) . Models of this brand have solid and collapsible sprocket types. To spin the clutches you need a nineteen head and handle. It should be noted that the thread is left-handed, and a deflector plate is installed behind the clutch (a consumable material that often breaks when diagnosing the drum).
- Partner (Partner) . A special feature of this brand is that when replacing a sprocket, it is recommended to change the bearing. If you ignore this step, after a scheduled repair there is a risk of chain failure, changing pitch during active sawing.
- Husqvarna (Husqvarna) . Many Husqvarna models use a variable sprocket
. This simplifies routine replacement and repairs. When disassembling the tool, you need a thirteen wrench to secure the shaft on the impeller side. - Carver (Carver ) Unlike other manufacturers, there are no specific design features of the coupling. Depending on the brand, the star can be solid or collapsible.
It is recommended to carefully read the instructions before starting scheduled repairs. It indicates the important design features of the saw and the frequency of replacement of consumables.
Features of saw designs
Professional chainsaw from STIHL
There are already several dozen chainsaws in operation from different manufacturers, capacities, and most importantly for special purposes. Saws are divided into:
- professional (for felling and construction);
- household (garden).
Accordingly, their drive gear will be different, as will the sequence of actions. This is a feature of saw gear devices. For most professional tools, the tire can change its position on the saw in two planes.
The main malfunctions of chainsaws and steps to eliminate them are described here.
Alternative solutions
The sequence of operating moments is identical for almost all known models on the domestic market of chainsaw equipment. Experts advise using a branded part for replacement.
If we are talking about modernizing this unit, the feasibility of such a change should be clarified by consulting an experienced specialist.
The best option is to purchase a repair kit, which also includes a replacement bearing. In addition to the key, you may need a clutch drum puller individual for each model, a metal or plastic stopper to fix the piston in a given position.
