How to replace a sprocket on a chainsaw. Restoration or replacement?
Expert recommendations: how to remove a star from a chainsaw correctly?
Chainsaw requires regular diagnosis and periodic replacement of worn parts. With regular operation, not only the saw set, but also the leading star is unusable. In this tool, it acts as a clutch disc, which is why it accounts for a significant load both when starting and during operation. The star on the chainsaw has a simple design, so it is easy to repair and prevention with it with your own hands. In the article we will consider how to determine the degree of wear of this detail and carry out a planned replacement.
Almost all models of modern chainsaws use a centrifugal type adhesion 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, transmitting rotation to the leading star. This reduces the load on the basic parts of the tool, extending the life and maximum performance.
Figure 1. Scheme of the device of the leading star
The clutch drum where the star is located can be located from the internal or outer part of the chainsaw building. There is always a cover on top to protect moving mechanisms from dirt, sawdust and dust. The coupling itself is a metal disk located in the coupling drum. The entire mechanism is attached to the crankshaft of the engine with springs with springs, along the edges of which there are friction pads. When the engine speed exceeds a certain value, a centrifugal force arises, which exerts strong pressure on the inside. After that, the star starts. The rotation of the chain saw begins.
Important! It is the asterisk that sets the chain of the chainsaw. All parts of this mechanism are closely related to each other, breakdown of the headset leads to a violation of the tool.
A little about the rules of operation of 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 as the assembly or manufacture of components, but in the class of tasks performed, performance and long.Term drive power. This predetermines the choice of the material of the leading asterisk for the chainsaw, its performance and the design of the saw chain.
The tools of the tool will be determined by the method of operation of the pair of “chain-outlet”. In most cases, users use one of two options:
- The chain is operated until the completely wear of the teeth, and then both the saw leaf and the stars are replaced at the same time;
- Periodic replacement of chains, having a different step, and each will need its own leading star.
The choice of option is often determined by the attitude of the owner to his tool. If you do not care what to saw (wood or stuck in it steel brackets, screws, etc.), then you can dwell on the first version. True, the chain will have to be ruled periodically, thereby reducing the performance of the chainsaw work.
It is strictly not recommended to leave the old chain with a new star and vice versa. With the wear of the saw blade, the probability that the step of the teeth will not match is almost one hundred percent. Therefore, at the initial moment of starting, both components of the chain transmission will be subject to significant dynamic loads. As a result, either the chain will stretch prematurely, “adjusting” to the asterisk, or when the hit will burst one of the teeth on the leading award.
In addition, it is worth focusing on the work of the bearing of the shaft of the leading star. During the operation of the saw in the operating speed mode, only the crankshaft rotates. But all the chainsaws periodically function at idle when the bearing rotates. With a lack of lubrication, there is a wear of the seat, and. As a result. An additional beet beam is still quite efficient chain transmission.
From this it follows that when replacing the chain and the leading stars for the chainsaws, it is not good to replace the bearing at the same time at the same time.
Classification of leading stars of chainsaws
The main difference between them is the frequency of replacement and the speed of wear: in the models of the “Prof” series, the wear is faster, and repairs are more often.
By constructive features, leading stars of chainsaws are:
The latter consist of a hub with a stationary crown of a certain number of teeth. Their factory pressing does not allow to remove the crown separately from the hub. This situation is characteristic of many Chinese chainsaws, for example, from the Champion brand.
The business with prefabricated stars is easier: the removable crown is quickly unscrewed from the axis of the drum, so the repair of special difficulties does not cause. This option is the advantage of most of European descent, for example, “Stihl” or “Husqvarna”.
How to remove an asterisk on a chainsaw
You can remove and change the asterisk at home without resorting to the service of the service center. The procedure is this:
- We unscrew the fastening of the saw headset with a special key;
- Unscrew and remove the headset lid;
- Unscrew and remove the air filter cover and the filter itself;
- We unscrew the spark plug.
To remove the asterisk, you need to fix the engine piston. To do this, we smoothly pull the cord of the kick starter, raising the piston up, but not bringing it to the end. Pour a long segment of the thick cord into the candle hole until the combustion chamber is filled. This is necessary in order to prevent the piston from passing the upper dead point. At the same time, the cord will serve as a damper, protecting the piston from possible damage. Part of the cord should exit the hole so that then it can be extracted.
To unscrew the asterisk, you need a special key that rarely comes with a set of saws, especially cheap models. You need to use a grocery of soft metal. Copper or aluminum.
The gap is leaning against the protruding of the cams of the centrifugal mechanism and inflicting non.Strokes with a hammer. The direction of the blow should be almost parallel to the plane of the coupling, since with a large corner you can bend the mounting of the cams and the clutch will have to be changed. Direction of the blow. Counterclockwise. Often, the inscription “OFF” and the arrow showing the direction of the blow are applied to the clutch.
You can not use steel gaps or a chisel, since there is a great risk of damaging.
After frightening the nut from the place, it can be unscrewed with your hands.
Some manufacturers of sawing clutch and sprockets use simple nuts with left thread. Then the task is simplified, because for removal you can take a simple open key of the desired size.
Chainsaw Repair. Replacing the Chain Brake (Echo Part # P021017220)
Now remove the leading star, trying not to lose the plastic gear of the oil pump drive and a needle bearing.
How to install
After all the work is completed, the asterisk can be replaced in good. Assembly is carried out in the reverse order. It is advisable to additionally grease the needle bearing.
When twisting the nut of great efforts, there is no need to attach, since it itself will be delayed during operation.
Types of stars
Depending on the class of the chainsaws, all stars are divided into two groups. Professional and household. The first type of parts have increased wear resistance, made of durable alloys of metal that is not subject to corrosion and mechanical damage. Household ones often require replacement and planned repair, with active use of the tool diagnostics, it is recommended every six months. By constructive features, the following types of stars can be distinguished:
- Prefabricated. The removable crown is easily unscrewed from the axis of the drum, which simplifies the verification and replacement of this part. Almost all European models of chainsaws are equipped with such stars.
- Solid. They consist of a hub and a stationary crown (the number of teeth can be different, you need to carefully read the instructions for the chainsaw). Due to the factory pressing, the crown can not be removed separately from the hub, so when damage it is required to disassemble the entire clutch drum. Such a mechanism is usually found on Chinese models.
If you plan to serve a chainsaw on your own, it is recommended to purchase a tool with a professional type of leading asterisk. It should be collapsible, which reduces the reduction in the repair and prevention of the tool.
Block: 3/7 | Summer characters: 1176
So that the mechanism of the chainsaw serves longer, you need to adhere to certain rules. Experienced masters recommend:
- Always lubricate the needle bearing after replacing the star.
- Correctly select the saw chain and tire. The step and chain step should match (for example, 3/8 or 0.325). If you use unsuitable consumables, then the asterisk is collapsed, quickly and unevenly wear out.
- Many try to replace the leading star and chain at the same time. The fact is that, as the chainsaw is used, the chain is inevitably stretched, accordingly, the length of its step changes and the length. And this negatively affects the sprocket itself, in particular, a wide step will wear it faster, breaking the grooves along the edges.
- Be sure to regularly clean the chainsaw. Periodically, you need to remove the side cover and remove the accumulated sawdust, which inevitably fall through the hole near the chain and mix with grease.
- Follow the “behavior” of the chain during operation. If it starts to wedge, this is an occasion to make an initial inspection of the leading star.
The algorithm of actions during the repair work of the chainsaw is quite simple and based on the experience and knowledge of qualified masters. Therefore, it is not recommended to neglect certain nuances. The instruction we presented will help to remove the sprocket from a saw with your own hands, without resorting to the help of specialists, on most types of chainsaws. In private, any deviations, non-standard structures are not excluded. Sometimes it is very useful to read the user’s guide to the tool, it may contain the necessary information about the design features, detailing spare parts with a description.
The drive design of most chainsaws presented in the domestic and semi.Professional segment of the market are fundamentally similar. The sequence of operations necessary to remove and replace the lead gear coincides.
Chainsaw Repair. Replacing the Clutch Drum (Poulan Part # 530057905)
As already mentioned, the best option would be to purchase a regular reptity for this model.
The advantage will be the presence of a kit and bearing. You should also check the presence of a drum puller intended for a given saw, as well as a latch for fixing the piston in a certain position.
If, nevertheless, there is a brilliant idea of “improving” or modernizing this node of the chainsaw, it is better to consult with specialists and just with experienced people.
What is needed to replace the stars on the chainsaw?
The main thing that is required is an understanding of the internal structure of the saw and a certain dexterity: if you hold this motor tool in your hands for the first time, it is better not to experiment with repairs and provide it to more experienced people.
If you are confident in your own technical literacy, you need: to replace the asterisk on the chainsaw:
How to replace a star on a Chinese chainsaw yourself
If you are faced with a tool where the star is placed on the thread (fixed instead of the bracket), then the replacement process will be somewhat laborious. Consider the sequence of actions in order:
- Initially, you need to remove the casing, as well as the tire and chain, as in the first case
- After that, a protective pad is dismantled, under which the air filter and the spark plug are located
- The spark plug should be removed. You need to screw it into the cylinder either a special plastic insert, or stick the cord. This is done in order to block the movements of the piston. The cord is used by woolen without sticking wire. The best option for such purposes is a wire from an iron
- Preference is given to the second option, since plastic inserts can damage the design of the piston. The cord is sat down in the cylinder, when the piston will not reach 2-3 mm to VMT
- When the movement of the piston is blocked, you should use a special key that is usually equipped with a tool. If there is no such key, you can use the one that is designed for the Bulgarians or the usual rye on “19”
- You need to rotate the device aside by the watch. As soon as the mount is weakened, you can display the device manually, dismantle the gear with a replacement, and similarly install all parts per place
At the end, when the star is fixed, the cord is extracted from the cylinder, and the candle is installed in place. A detailed description of the dismantling process is presented in the video.
After the work done, you will need to adjust the tension of the chain, and resort to the verification of the tool in action. The replacement process can be considered complete on this. How the stars of the chainsaw is replaced, and what this procedure is, is described in detail in the material. If you are faced with various problems, then seek help from specialists who will help to understand the situation free of charge.