The device and principle of fastening
The procedure for servicing the components of the working mechanism requires practical skills, but the correct theoretical training is of great help and is no less useful for the process. Before we tell you how to remove the clutch from a chainsaw, let’s clarify and shed a little light on the mechanism structure. Let’s start with the location, which is invariably to the right of the crankcase, under the tire cover. Most saw models have a centrifugal mechanism in the foreground, and a drum behind it (Husqvarna 137), but there are designs with an opposite installation (STIHL 180).
The clutch is at the left-hand threaded end of the crankshaft onto which the clutch is screwed. The drum with the chain sprocket, on the contrary, runs freely and is installed on the shaft through a needle bearing. The clutch is located inside the drum, and its pads “shoes” are pressed by springs to the center. When you press the gas, the revolutions and rotational speed of the centrifugal mechanism increase, spreading the pads to the sides from the center and pressing them against the inner walls of the drum, transferring motion to it. A similar device for the chainsaw clutch automates the course of the chain, starting it only when the speed rises and stopping it at idle.
Of the additional nuances, one can single out serious design differences in the clutch components, which are individual for numerous models of chainsaws. A common model of the clutch has 3 shoes, tightened by ordinary springs, but there are designs with two or four “shoes”, and metal plates can be used as a tie.
Drum differences can be expressed in the number of teeth that define part standards (6 for 3/8 “chain and 7 for 0.325). Also, the sprocket can be cast or collapsible. In the first case, it is just an ordinary drum with teeth, and in the second, a crown is put on them, into the grooves of which the chain shanks are inserted.
How to unscrew the clutch on a chainsaw
The operation of removing the clutch and the drum is quite simple and takes about 1 minute with a full hand. If you find out the nuances and prepare in advance, there will be no problems, but with a spontaneous approach, the procedure is significantly delayed, if not disrupted at all. The instruction below, clearly and step by step, demonstrates how to disassemble the clutch on a chainsaw in different ways, using the available tool.
The first and easiest step is to remove the tire cover by unscrewing the 2 fastening nuts with the hex wrench supplied with the chainsaw. The guide bar and chain can also be removed (if installed).
If the drum is located on the outside, it is enough to remove the retaining ring to remove it. It is more convenient to carry out this operation with a slotted screwdriver.
Since the overrunning clutch is attached to the shaft, an attempt to unscrew it will only cause the parts to rotate. It is necessary to fix the position of the crankshaft by installing a stop for the piston through the spark plug hole. As a stopper, you can use special devices, the cost of which starts from 200 rubles. If there is no opportunity and desire to spend time looking for such a stop, you can always place a regular cable with a knot in the combustion chamber.
After fixing the position of the shaft, you can start unscrewing the coupling. Usually it does not have a convenient nut for a spanner, and disassembly involves the use of a special puller. The cost of such a device starts from several hundred and often exceeds the cost of the coupling itself.
Alternatively, you can use an angle grinder wrench or use gentle hammer blows to break it off with a chisel. Alternatively, you can use a chainsaw tire by passing 2 short bolts into its holes and tightening them with nuts from the back. You can make a homemade clutch remover by marking and drilling in a sheet of metal (from 4 mm), corresponding to the grooves, holes into which to thread and tighten the screws. In general, there are many sophisticated ways to “hook” the clutch at no extra cost. Some unscrew with a simple wrench or pliers.
Having broken the fixation of the overrunning clutch, we continue unscrewing it clockwise (left thread).
Under the coupling, there may be a large metal washer on the shaft that separates the components (not on all models). We take it out, and after it a drum with a needle bearing. Clutch removed.
If the guidance presented above does not fully convey the essence, reinforce the knowledge gained with a visual demonstration of the entire process. The following short video instruction, with useful Комментарии и мнения владельцев from the author, will explain in detail how to remove and repair the chainsaw clutch with your own hands, with minimal time costs.
The description of the clutch release process can be called universal, applicable to all modern saw models. As mentioned above, the main design difference can manifest itself in the location of the sprocket, which is usually located inside (between the clutch and the crankcase), but it can also be installed outside (it is much easier to change this). Otherwise, if you want to figure out how to remove the clutch from a Partner or Husqvarna chainsaw, just read the instructions above, reflecting all the stages of the process. Small nuances characteristic of certain models (fastening the duct cover, chain tensioner) usually do not cause difficulties and are easily resolved on their own, or with the help of technical documentation.
All chainsaws have the same design, regardless of which device, domestic (Ural, Kedr, Patriot 3816, Carver. Russian production with Chinese partners) or foreign (STIHL, Husqvarna), for example, repairing a Patriot 3816 chainsaw with your own hands will be the same as well as fixing a foreign device. The main components of the tool:
- Fuel tank.
- Tire with chain.
The general principle of the chainsaw operation is simple. the master sharply pulls the cord, which starts the engine, and he, in turn. the saw blade. Sometimes, the device malfunctions, in order to eliminate them, you will have to dismantle the saw. Problems that may arise with a chainsaw:
- It just won’t start.
- Starts up, but after a while stops working.
- Doesn’t work in cut.
- Power drops.
The main problems that arise are related to engine problems (fuel supply, exhaust system, cylinder-piston system and ignition), or smaller problems (chain problems, lubrication, tire, oil seal). It is important to consider each problem in more detail.
If the chain simply breaks, then it should be replaced with a new one. There shouldn’t be any problems with solving this problem. Repairing other parts of the saw can take up to several hours.
No matter how trite it may sound, if the chainsaw does not start, then you need to check the tank for the presence of gasoline. If there is fuel in the system, then the breather may be clogged, equalizing the pressure when fuel is supplied. The breather can be cleaned with a sharp awl or needle. With a candle wrench, the candles are turned out and cleaned with sandpaper. You can also ventilate the combustion chamber. After these procedures, the saw should start.
If the saw shuts off automatically, the trigger is most likely defective. But sometimes it happens that it’s not about him. In this case, you need to unscrew the candles and inspect them carefully. If traces of fuel are visible on them, it means that the carburetor is incorrectly adjusted. The spark plug must be cleaned and placed back, after shutting off the fuel supply.
If black carbon is visible on the candles, then the matter may be in poor-quality oil, a poorly adjusted carburetor and an incorrectly calculated ratio of oil and gasoline. In this case, you also need to clean the candle and place it back.
When checking the spark plug, you need to consider the distance between the electrodes. The optimum clearance is between 0.5 and 0.65 mm. The used gasket must be replaced with a new one.
It is also important to check the device for sparks. This is easy to check: you need to connect the spark plug to the ignition cable, use pliers to connect the cylinder and the plug nut, and then observe the presence of a spark. If it is not there, the candle must be changed. If, when changing the spark plug, it turned out that the other does not give out sparks, then the problem may be an inoperative contact with the spark plug or high-voltage wire.
Why is the fuel system not working??
Cylinder not receiving fuel mixture? Why is this happening?
- the hole in the breather (this is the cover) is clogged. The presence of a vacuum impedes the supply of gasoline;
- the fuel filter in the tank is very dirty;
- the cylinder is not receiving enough fuel from the carburetor.
Disconnect the fuel supply hose and you will see if it is leaking from the hose. The breather and filter check is canceled if the jet is full and strong. If there is a weak admission, it means that you found that it was broken.
Clean the breather with a sharp needle. Remove the fuel filter from the filler hole of the fuel tank, which has been empty beforehand. This can be done using a wire hook. Also, the hose that sucks in must be disconnected. Clean the filter and replace it if necessary. According to the recommendation of the largest manufacturers, it is better to change the fuel filter at least once every three months.
There is insufficient fuel or the proportions of fuel and air are not observed: the air filter may be clogged, the carburetor is not adjusted, its channels or filter screens are clogged.
Very often, to make repairs to a chainsaw, you have to clean the air filter, as it very soon becomes dirty. As a result, there is a decrease in the amount of air that enters the carburetor, and the fuel is extremely rich, the engine stops working normally.
When removing a dirty filter, be careful not to get dirt from the filter to the carburetor. After a simple cleaning of the filter, or after washing in water with a detergent, dry this part, put it back.
To adjust the carburetor, apply three screws, maximum, minimum, and idle. Follow the instructions to avoid damage to the engine.
You have adjusted the carburetor, and nothing has changed. clean all the channels and the filter screen, check if the membrane is intact. The most difficult mechanism for a chainsaw is the carburetor, it must be disassembled and cleaned very carefully and carefully. Small details can get lost, be careful where you put them. Reassembly will cause problems without them.
The chainsaw engine may not start due to problems with the muffler, which is clogged as a result of fuel combustion. Normal exhaust does not occur. To remedy the situation, remove the muffler, disassemble and clean with a damp cloth. If the muffler cannot be disassembled, after washing it, dry it with a hair dryer. When you remove the muffler, plug the hole with something to avoid inhaling carcinogens.
The muffler is clogged due to the use of excess oil (more than recommended). Or you may have purchased a low-quality lubricant.
How to disassemble the crankcase and remove the crankshaft on a STIHL MS 361 chainsaw
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The reason for the absence of a spark may also lie in a faulty ignition module or a violation of the gap between it and the flywheel magnetic circuit. It should be 0.2 mm. A gap violation becomes especially likely if the saw was disassembled before the flywheel and ignition module were removed. The gap is set with a 0.2 mm spacer placed between the flywheel boss and the ignition module. Defective ignition module must be replaced.
Having checked the ignition system in this way and not finding a malfunction, you can go to the fuel mixture supply system.
Fuel supply system. If by inspection of the spark plug it was found that fuel does not enter the cylinder, all possible reasons for this need to be considered. This could be:
- no fuel flow from the tank due to a clogged hole in its lid (breather), while a vacuum is created in the tank, which prevents fuel from flowing out;
- contamination of the fuel filter installed in the tank;
- non-flow or insufficient flow of the fuel mixture from the carburetor to the cylinder.
To diagnose the first two reasons, it is enough to disconnect the fuel hose from the carburetor and see if fuel is leaking from it or not. If it flows with a full stream, the breather and filter need not be checked, if it does not flow or flows weakly, we can assume that the cause of the malfunction has been found. The breather is cleaned with a needle. The fuel filter is removed through the filler opening of the empty fuel tank, with a wire hook, together with a suction hose from which the filter is disconnected and cleaned or replaced with a new one. Chainsaw manufacturers recommend changing the fuel filter every 3 months.
DIY How To Remove Chainsaw Flywheel Without Puller. Stihl Husqvarna, Echo, Poulan
What are the breakdowns in chainsaws
All troubles fall into two main categories:
1.Problems in the engine, including all its components and systems. ignition system, delay with fuel supply, malfunctions: cylinder-piston group, exhaust system.
Breakdowns in all further units: brake chain, lubrication system, clutch problems, tires.
In addition to the aforementioned clogged breather, other fuel supply problems may occur. The main obstacles can be:
Littering of the fuel filter. To check the device for this malfunction, you need to disconnect the fuel hose and see how the fuel flows. If the jet is weak, the filter may need to be cleaned. The filter device is removed through the filler hole of the tank and cleaned out, if the contamination is too strong, it is changed.
Professionals recommend changing the filter every few months, regardless of how dirty it is.
Lack of fuel. In this case, the problem may lie in several factors. The first is the contamination of the air filter. The problem is that there is not enough air being delivered to the carburetor, which results in poor engine performance. The filter must be removed, cleaned, rinsed and dried, and then put back.
The second reason is an unregulated carburetor. It, that is, the adjustment is carried out with three screws.
And the last reason is a problem with the integrity of the membrane or contamination of the carburetor channels. As in other cases, it is necessary that the components are dry and clean.
The main problem that arises during the repair is the lack of the necessary information on how to carry out the repair. This is due to the fact that many foreign manufacturers believe that the saw should be disposed of after a certain period of time and use up. Therefore, many craftsmen have certain doubts, especially when repairing budget models.
But expensive professional models also create certain difficulties:
- The first problem is to supply expensive spare parts.
- For the maintenance and repair of some units, special equipment is useful.
Design and principle of operation of the drive sprocket
The quality of the maintenance of the tool largely depends on the understanding of the device of its nodes, therefore, for the sake of completeness, we will conduct a brief educational program on the types and characteristics of existing transmission elements. The drive gear of the chainsaw is located on the clutch plate and is set in motion when the engine speed rises. These elements can have an all-metal or collapsible design. The first option implies a complete replacement when worn, and in the case of the latter, it is enough to replace the removable crown.
The sprocket dimensions limit their use for all chain types. There are 2 common standards: with a pitch of 0.325 mm and 3/8 inches (the most important parameter when choosing for replacement). Such standardization is due to the power capabilities of the chainsaw engine. In addition to the sprocket pitch, the choice should be based on the number of teeth (6 or 7) and the inner diameter of the bowl, but it is best to start from the specific model of the tool you have.
How to remove an asterisk from a chainsaw and replace it with another one (instructions with photos and videos)
One of the most loaded parts of the mechanism, subject to the most rapid wear. The drive sprocket (gear), located on the chain saw clutch, transfers rotation to the chain, resting on its links at high speed. In conjunction with the serious resistance of the material into which the blade “bites”, the gear takes on the maximum pressure, which gradually grinds the metal of the teeth.
With wear and tear, the sprocket begins to play, causing extremely unpleasant consequences. Fortunately, this element belongs to budget consumables, even for professional brands of chainsaws. How to determine the time for replacing an asterisk, do it yourself and extend the service life for a new one, we tell and show in this article.
How to remove an asterisk from a chainsaw
Depending on the brand and model of the instrument, the design features of its system may differ, but the principle of the interaction of the components itself usually remains unchanged. The method of installing the drive gear is identical for all modern-type chainsaws, whether it is a professional Husqvarna or a Chinese no-name. the differences are minimal (not counting the quality). The only major difference may be the sprocket location, which can be inside (between the clutch and the engine) and outside (on the clutch). The most common option is represented by the internal fastening, so we will start the description of the removal process with it.
First of all, you should prepare auxiliary means, without which it is almost impossible to remove the fixed clutch. To prevent the crankshaft from spinning, you can use a special retainer that is screwed into the spark plug hole, or you can put an ordinary knot made of a cable or thick cable into it (this is even more delicate). You can remove the clutch drum using a special puller, an angle grinder wrench or a conventional hammer and chisel. For a more secure attachment of a new sprocket, it is better to stock up on a tube of thread lock in advance.
- The gear replacement process begins with removing the chain, saw bar and removing the spark plug from the socket.
- We turn the clutch so that the piston goes down and put a retainer or knot in the spark plug hole.
- We insert a puller or key into the clutch, and unscrew it clockwise. When disassembling for the first time, it can be quite difficult to rip, and it is likely that you will have to knock with a hammer.
Even with minimal experience, figuring out how to unscrew an asterisk on a chainsaw is extremely simple. The process can be complicated by a strong thread lock, so it is better to carry out these works with an assistant. For the most vivid demonstration of the process, we recommend watching the following video, where the author briefly but in detail shows how to remove an asterisk from a Partner chainsaw, with the subsequent installation of a new part.
The second option for removing the sprocket, when it is located outside, does not require unscrewing and even fixing the piston. The element is fixed on a retaining ring, which is enough to slightly bend and remove, making way for the extraction of the gear. In the reverse order of the assembly process of the drive unit, you should pay attention to the presence of a washer, which plays the main role of a stop.
Replacing the drive sprocket on a chainsaw
Once the defective component has been removed from its seat, the procedure for installing a replacement is not a hassle and is simply done in reverse order. The new bearing that comes with the sprocket must be lithium greased (no fanaticism). Typically, the bearing life is enough for 2-3 gears, which allows you to save money without purchasing a complete set.
In order to avoid loosening the clutch when using the tool, it is strongly recommended to apply a retainer to the threads. It is better to use a collapsible one (blue), since the red one will have to be heated with a building hair dryer to remove the asterisk with the next wear. Tighten the clutch with force using accessories (clutch puller or bolt wrench).
For a more complete visualization of the assembly process, the following photo instruction is presented, demonstrating how the sprocket is replaced on a Husqvarna chainsaw. On the example of this model, you can perform maintenance on any saw with an internal drive gear.
How to remove and replace an asterisk from a chainsaw?
Many owners of gasoline chainsaws after a device breakdown are worried about how to remove a chainsaw sprocket.
When replacing the sprocket, all work must be carried out carefully and with care.
The design of the chainsaw device is a classic mechanism that is driven by an internal combustion engine. The design of the unit uses one of the simplest single-cylinder two-stroke carburetor engines that run on gasoline. The simplicity of the engine and the design of the chainsaw as a whole is the key to the trouble-free and reliable operation of the device in harsh operating conditions. Chainsaw operation does not require a large amount of knowledge and skills from the operator. The only condition for long-term and trouble-free use of the device is the implementation of regular technical inspection and maintenance of the device. In the process of working with the device, it is required to regularly replace the wearing parts. To reduce tool wear, control the lubrication quality of the saw chain, its tension, the degree of chain wear and the degree of wear of the drive sprocket.
Before repairing a chainsaw, you should study its design. To replace one of the main structural elements of the device. the drive sprocket. it is required to study the mechanism of the clutch of the unit.
Method for a star with a collapsible clutch drum
Do not forget that installing a new chain on a 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 alternate 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. Experts recommend changing it simultaneously with the chain and sprocket and systematically lubricating it with chain oil.
Method for a star with a stationary crown
- dismantling of the protective cover and tire cutting set;
- locking of the piston part of the motor;
- disconnecting the clutch from the engine system;
- notch from the saw body of the clutch and the centrifugal sprocket;
- visual inspection of the sprocket and its toothed part;
- if defects are detected, replace the sprocket with a new clutch drum;
- diagnostics of the chainsaw clutch elements for defects. worn out centrifugal springs and cams can negatively affect the operation of the sprocket;
- if there are no faults, proceed to the assembly stage. For this you need:
- remove the stopper;
- pull back the ignition cable;
- screw the stopper to fix it on the motor shaft of the centrifugal mechanism;
- clamp the clutch with a universal wrench in the direction opposite to the chain;
- return the remaining removed parts to their original positions.
When to change the chain saw sprocket?
If the chain glues at low speeds, the saw is operated for a long time on one chain and a drive sprocket, and during its inspection defects are established, its change is mandatory.
Outwardly, the condition of the sprocket is determined by its teeth. They are considered worn out if they are:
Chainsaw crank case split and bearing removal
- there are small chips or grooves from the guide;
- their width is disproportionate to their height;
- angles between teeth and depressions are different;
- hub with scuffing and other deformations due to lack of lubrication.
In each of the above options, the sprocket is subject to repair.
Algorithm for replacing the clutch drum
For trouble-free use of the chainsaw, regular technical inspection is necessary.
When replacing the clutch drum, only a strictly defined type of structural element of the device should be used for installation. When replacing the drum, the bearings of the structural element should be changed at the same time.
To carry out repair work, you should purchase a special repair kit, which includes a drive sprocket and a bearing. After purchasing a repair kit, prepare the materials and tools required for the repair. The main tools that will be required when carrying out repairs are the following:
- universal wrench that comes with the chainsaw;
- piston stopper, can be made of plastic or metal;
- special puller of the centrifugal mechanism or clutch drum.
The work procedure consists of several stages. Each stage has its own characteristics depending on the design features of the chainsaw, but the scheme and sequence of work is the same for any model of the unit.
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 located both outside the chainsaw, and on its 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.
The main reasons for replacing the drive sprocket
The universal wrench is the main tool you will need when replacing the sprocket.
The most common reasons that force the tool to be repaired associated with the replacement of the drive sprocket are:
- jamming of the chain due to the occurrence of defects during the operation of the unit;
- high wear of the sprocket as a result of long-term operation of the unit.
With regular use of the device, increased wear of the drive sprocket occurs as a result of the application of increased loads on it in the process of sawing wood. There are two ways to operate the device:
- using one saw chain;
- using several saw chains alternately.
When using the first method of operation, the chain is operated until it is completely worn out. This method has several disadvantages. The main one is the problem of monitoring wear during intensive operation of the unit.
When using two or more chains in the process, it is possible to achieve uniform wear of the chains and sprocket, which allows you to extend the period of operation of the device before repairing the sprocket. In addition to the wear of the sprocket, one should not forget about the bearing that is installed in the sprocket. This structural element works at any engine speed. When replacing the sprocket, change the bearing at the same time.
The clutch complete with the sprocket must be replaced in a timely manner. If the repair work is not carried out on time during the operation, the tool experiences increased vibration, which leads to an increase in the wear of the bearings installed in the internal combustion engine on the crankshaft axles. The maximum depth of wear of the sprocket teeth should not exceed 0.5 mm. The life of the sprocket is twice that of a single chain, so two chains should be used during operation. After the chains have reached the end of their life, replace the chains and the drive sprocket at the same time.