How To Remove The Drive Sprocket On A Husqvarna Chainsaw

30th July 2020

Replacing the sprocket on the Husqvarna chainsaw Replacing the sprocket on the Husqvarna chainsaw Recommendations: how to remove the sprocket from the chainsaw Features of the clutch drum in chainsaws Algorithm for replacing the clutch drum Many tools.

Algorithm for replacing the clutch drum

The chainsaw clutch covers the sprocket.

First of all, it should be noted that when buying spare parts for a chainsaw, you need to strictly observe the type of drum or use the advice of a specialist when it comes to modernizing it. As a rule, when the drum and saw chain are replaced at the same time, the drum bearings are also replaced.

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

Universal wrench sold with chainsaw
Mechanism piston stopper (plastic or metal in standard versions)
Puller of the centrifugal mechanism or clutch (selected depending on the model of the chainsaw).

During the operation, the following actions are performed:

Chainsaw sprocket location diagram.

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

In order to replace the sprocket on a chainsaw, all work must be done carefully and carefully.

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

Recommendations: how to remove an asterisk from a chainsaw

Features of the clutch drum in chainsaws
Algorithm for replacing the clutch drum

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

The clutch drum, called a sprocket, is an integral part of your chainsaw.

How to remove an asterisk from a chainsaw: self-replacement

Today, almost every resident of a country house or summer resident has his own chainsaw. You cannot do without it during regular logging, gardening and municipal work. The demand for chainsaws does not fall, but even grows due to the fact that these devices do not require much knowledge and skills to work. The only thing that needs to be done regularly is to carry out technical inspections.

As with any tool, chainsaws require careful personal care. It is necessary to constantly check the oil supply to the chain, chain tension, brake operation, ignition system and other things. Fortunately, almost any malfunction can be solved at home on your own.

Reasons for replacing the sprocket

Replacing the sprocket on a chainsaw with opening and revising the entire clutch unit is made 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.

Usually sprocket working life about twice the lifespan of one 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. These should primarily include:

Chain with cutting edges;
Guide rail;
A chain sprocket driven into 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.

Chainsaw clutch system device

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

Clutch basket has the shape of a disc. It has movable friction pads that can move radially. In the normal state, they are pressed against the center by the built-in springs without touching the drum of the driving sprocket of the chain drive.

how to remove the drive sprocket on a Husqvarna chainsaw

Reasons for replacing the sprocket

Replacing the sprocket on a chainsaw with opening and revising the entire clutch unit is made in the following cases:

Jammed chain movement;
Physical wear of the sprocket to unacceptable limits.

Chainsaw sprocket replacement

Chain with cutting edges;
Guide rail;
A chain sprocket driven into 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.

Chainsaw clutch system device

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

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 adhesion to 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.

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 bar can change its position on the saw in two planes.

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

Sequencing

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, they use a soft cord with a diameter of 5-6 mm.

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

It is necessary to open the side cover to gain access to the tire and sprocket.

Next, you need to remove the tire by loosening the chain.

It looks like a chainsaw tire

After the sprocket is free, you need to unscrew the spark plug to access the engine piston.

Turning the sprocket manually, bring the piston almost to the very top of the channel and fill the hole 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 :

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 speed exceeds a certain value, centrifugal force is generated, which exerts strong pressure on the inside of the drum. After that, the sprocket starts up. The rotation of the chain saw begins.

How to unscrew?

It is easy 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 carry out cleaning 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 construction is difficult to repair. It is required 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

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

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.