How to unscrew the clutch on a Chinese chainsaw
Chainsaw clutch replacement and repair
Chainsaw clutch malfunctions are one of the most common failures of this technique. The question of how to remove the clutch on a chainsaw at home correctly and not harm the tool is thought not only by inexperienced technicians, but also by specialists who have repaired it more than once. This is due to the fact that the clutch is an important key element of chainsaws of any power class and brand, on which their serviceable, long-term and successful operation depends.
In cases where gasoline cutters start to start badly, slip instead of starting, checking the clutch for faults is mandatory, recommendations regarding which will be presented further.
How to remove a clutch from a chainsaw: a detailed report
The clutch repair process consists of the following operations:
- dismantle the chain set, air filter flaps and the clutch itself;
- lock the crankshaft. for this it is enough just to unscrew the ignition cut;
- unscrew the clutch with a special wrench with strong movements clockwise or counterclockwise (different saw models can have both left and right threads). Usually, a tool for removing the clutch is included with the chainsaws;
- go to disconnecting the drum and sprocket;
- if, when inspecting the clutch, one or more cracked springs were found (there may be several of them, for example, for Husqvarna chainsaws. 3 units). you need to replace the broken spring with a new one;
- assemble the clutch on the chainsaw, put it in place and screw it in. Remember that the crankshaft must still be stationary;
- mount the removed parts on the saw in the reverse order to disassembly;
- fix the clutch. move the auxiliary brake handle forward, start the device and carefully remove from the inertial brake.
The device and principle of operation of the clutch of chainsaws
Modern chainsaws are equipped with centrifugal clutches. This means that their work entirely depends on the torque of the motor, which the saw gives out at a particular moment in time.
Its main structural elements are:
The principle of operation is as follows. When the saw is started, the elements that move freely in the radial direction are pulled together by springs to the shaft axis. In this case, the torque does not go to the drum, which means to the sprocket and the guide. At the moment when the centrifugal force prevails over the force potential of the springs, the clutch elements weaken and compress at the inner part of the drum, initiating its torsion. Together with it, the rotational cycle goes to the sprocket and the tire-chain set itself.
The main advantage of this type of clutch is its slippage when the cutting part is suddenly braked, which does not stop the engine. As a result, the “heart” of the saw. the motors remain safe and sound.
Clutch repair: the nuances of the process
When servicing clutches yourself, you need to know that:
- several saws have a washer that sits between the sprocket and the clutch and the sprocket and the motor. Consider this when repairing;
- the special spring of the oil pump drive must not be damaged during disassembly, and must also be returned to its original position. Otherwise, the chain will receive less lubrication or no longer lubricate at all.
The tool that has been repaired must be checked for the reliability of the bolt ties, the supply of lubricant to the chain and the serviceability of the motor (it must turn on smoothly and work smoothly). Only then can it be exploited.
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.
AUTO OILER REPAIR, TEST, PUMP AND WORM GEAR CHINESE CHAINSAW CLONE PDTO Coocher
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.
Repair kit, required tool
In order to remove, disassemble or adjust the clutch, we need the following tools:
Dismantling the chainsaw clutch:
How to remove the clutch from a chainsaw and put it back in place?
Diagram of the process of removing the clutch from a chainsaw (for example, let’s take a situation when a drum needs to be replaced):
- remove the saw headset using a universal key;
- remove the chain, tire;
- unscrew the air filter cover;
- then we twist the candle;
- we fix the piston with a stopper or rope;
- remove the clutch with a punch (puller) or a universal wrench to remove the clutch;
- remove the clutch by unscrewing it clockwise;
- remove and replace the drum.
After the steps described above, the entire assembly is carried out in the reverse order.
There is no such thing as “clutch adjustment”, but other components are usually adjusted, such as the carburetor, fuel system, starter or clutch. In order to adjust the clutch it is necessary:
- Change the washer, which is located between the engine and the sprocket or, in other models, between the drum and the sprocket;
- The stretched spring in the assembly cannot be pulled off, so it must be replaced with a new one. If you continue to cut with a defective spring, the lubricant will not flow to the chain, and this will lead to tool breakage.
|The chain rotates without stopping, with any carburetor adjustments. Engine runs unstable.||The spring burst in the drum.||Remove the spring and replace it with a new one, or put a new unit.|
|The chain spins almost constantly, making extraneous sounds.||Cam chipping.|
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How to remove the clutch on a chainsaw?
It is not necessary to consider the instructions for this type of work for a single model, because for all one universal is used, which allows you to dismantle this unit on modern gasoline tools.
If there are any distinctive nuances, then they relate to individual clutch parts. For example, some brands create one spring with two sections in the design of this assembly, which must be taken into account when completely replacing this component (it must be replaced when the spring is damaged, due to which the chain will rotate, and the engine will demonstrate unstable operation).
To dismantle the clutch, we adhere to the following algorithm of actions.
- We dismantle the entire headset. Also remove the cap located on the air filter and clutch.
- We manually stop the crankshaft so that it does not rotate. It is more convenient to do this using a rope that is threaded through the candle hole, while removing the candle itself. Do not forget that for this you need to securely fix the piston in one position. Alternatively, remove the starter cap and screw a pair of bolts into the rotary mechanism of the ignition system.
- Using a special key, which is usually included in the package of the tool, unscrew the clutch (you need to unscrew it with counterclockwise movements). There is no need to be afraid to make efforts, usually the fasteners of this unit on modern chainsaws are strong.
- Removing the drum and guiding star.
After that, you can install new parts (which needed to be replaced). Twisting the fasteners, we make movements in a clockwise direction. Don’t forget about the crankshaft where the starter is located. It needs to be stopped.
When assembling, we adhere to the same algorithm of actions, but in reverse order.
When screwing in the assembly by hand, use the chain element brake handle to secure. Tilt the tool forward, try to start it, release the machine from the brake.
Speaking about a complete replacement of the clutch, do not forget that experts recommend changing the unit after two replacements of the guide. It is necessary to take into account the following nuances when servicing the clutch:
- some saws have a washer located in the gap between the clutch and the sprocket (the motor and the sprocket sometimes), this must be taken into account during repair work;
- disassembling the tool, dismantling the clutch, try not to damage the special spring of the oil pump (drive this unit), do not try to put it in its original position, otherwise this will cause reasons with the supply of lubricant.
Before operating the saw, on which the clutch was repaired, check the unit for proper operation of the engine, the reliability of fixing the bolts, test the lubrication system.
Types of clutch breakdowns
The types of faults do not depend on the model of the chainsaw, since the structure and principle of operation of the clutch is the same on almost all modern power units. Chainsaw operators know that a minor problem with this unit requires immediate action. Failures are inevitable, as the clutch collides during less intensive use of the tool with a large load. Often the problems are related to:
- wear of the unit as a whole (the spring may burst or the mechanism will begin to slip);
- damage to the spring (the chain will rotate, the engine will work, but unstable);
- chips formed on the clutch cam due to heavy load or overheating (it is enough to listen to the unit during its operation, extraneous noise indicates a malfunction).
Whatever the reason for the poor performance of the clutch and related components, you need to remove the clutch in order to repair it. Please note that repair work does not always give the desired result, so sometimes you need to replace the clutch on a chainsaw. All of the above manipulations can be “cranked” independently, without asking for help from the specialists of service centers.
Be sure to read the article where the correct gap on the chainsaw candle and its device is considered.
This article will focus on sinks, their design and operation.
The basic structure of this element on all modern chainsaws is the same. However, the technical design is different, therefore, different brands and models may require different tools.
To remove the clutch on all chainsaws, you need:
Chainsaw Clutch replacement
- Screwdriver for removing the retaining ring from the shaft with a gear cover,
- Depending on the model, you will need a regular wrench to unscrew the centrifugal mechanism (drum) itself, or a wrench with two cotter pins, such as the one used to tighten the nuts on an angle grinder.
- A stopper is required in order to fix the flywheel shaft (crankshaft) on which the centrifugal mechanism is twisted.
The crankshaft is locked by locking the piston in the cylinder with a soft metal bar or rope with knots tied.
It is undesirable to use hard metal, it can damage the piston. Weak materials such as plastic cannot be used either. They can break, crumble and fall into the cylinder windows, carburetor cavity or crankcase. Then a complete disassembly of the engine will be required in order to remove them from there, and these are unnecessary problems.
Don’t have a puller? Then we use the rope as a stopper.
This is how the original stopper from STIHL looks like, but you can just as well use the free option. a rope from the starter with knots. 1-2 knots are enough.
Examples of dismantling on the most common tools
All chainsaws have the same clutch design, only two well-known brands have significant differences: STIHL and Husqvarna, and all other saws have a similar design to either the first or the second brand.
Replacement nuances on Husqvarna gasoline saws
With the same operating principles, the technical design of the clutch on Husqvarna differs from Calm and some other brands.
- The drum cover with a drive sprocket is not located on top of the mechanism, like in Calms, but under the eccentric mechanism (basket). Therefore, to replace this part, the entire basket is removed. (On Calm, this cover is on top; for replacement, it is enough to remove the retaining ring and do not remove the entire drum).
- On Husqvarna, a hexagon in the form of a nut is not provided for unscrewing the basket of the eccentric mechanism with a hex wrench. Instead, there are holes for key cotter pins like those used to tighten the monkey nuts.
In professional services and workshops, for dismantling Husqvarna baskets, special probes for the piston stopper and key-sleeves with two studs for the expansion and twisting of the thread are used.
Such a tool is not cheap. And for a one-time work in a home workshop, it makes no sense to acquire it. Therefore, the piston is locked with a rope as described above.
The clutch detailing on Husqvarna saws, as you can see, is no different.
To unscrew, use a suitable sized monkey wrench with two spikes or the tire of the chainsaw itself. At the end of the tire, which is hidden under the cover, there are two transverse holes located perpendicular to the adjustment groove. In terms of location, they match the dimensions of the holes for unscrewing the basket. Insert two screws into the holes of the bus, fix them with nuts. The diameter of the screws must fit into the holes of the mechanism. The result is a key with two spikes and a powerful lever.
The use of a Husqvarna tire instead of a special key is illustrated in the video from 2 min 35 seconds. Commentary in a foreign language, but the process is clear.
Not all saw bars have these special holes. However, they can be drilled. And not only on the tire, but also on a strip of metal 3-5 mm thick. In this way, you can make a suitable wrench for removing / installing this part. The main thing here is to accurately measure and drill the holes so that they match the holes on the drum.
On all Husqvarna household chainsaws, the clutch has an identical design and, accordingly, it is removed in the same way, for example, on models 137 and 142, there is not even a visual difference.
Chainsaw clutch Husqvarna 137
How to unscrew on Chinese saws like Huter, Partner, Carver?
The most significant differences in the technical design of the clutch and the methods of dismantling between the German STIHL and the Swedish Husqvarna. They are described above.
Dozens of other brands, including Partner, Huter, Carver, are variants of these two main brands.
The dimensions of the nuts, the pitch of the thread on the shaft, the diameter of the baskets themselves, the distance between the holes for the special keys, retaining rings and methods of their fixation, the shape and location of the springs may differ. But in general, the device and methods of removing baskets of all modern chainsaws are identical.
Patriot chainsaw clutch, visually similar to Husqvarna’s design
How to remove the clutch using the example of a chainsaw Piece il 180
Dismantling the clutch drum on STIHL 170, 180 chainsaws has its own specifics and is somewhat different from the same operation on other brands. By the way, we also recommend reading how the 170 and 180 models differ, the article reveals the most interesting differences that are not visible at first glance.
Specifically: these Calms have a thin crankshaft connecting rod carrying a piston. With a rigid piston stop and a strong load on the shaft, the connecting rod can easily break when unscrewed. At the same time, the thread of the drum nut on these models is usually unscrewed easily.
Therefore, it is not necessary to lock the piston with a rope or rigid rod. Instead of a piston stopper, the spark plug is left twisted, which makes it difficult for the piston to travel. The nut is unscrewed with a socket wrench driven by a pneumatic or electric wrench at high key speeds. At the same time, strong air compression is formed in the combustion chamber, the piston stroke is difficult, and the high speed of the wrench allows you to unscrew the thread.
On Calm and on most models of other brands, the basket thread is unscrewed clockwise (left-hand thread). These reverse threads are used on parts that rotate counterclockwise during operation. Left-hand thread in these cases avoids untwisting and provides “self-tightening” of the thread during operation.
When there are no wrenches, the basket is unscrewed by blows while the candle is screwed in. A bar is placed in the window of the centrifugal mechanism, and it is hit with a hammer. As a rule, two to four strokes are enough to break a threaded tie from its place.
Specifically, the unscrewing process “by impact” on the STIHL 180 is shown in
The disassembly procedure is very simple and consists of only 4 steps, get acquainted, step by step instructions with
The assembly is carried out upside-down. Before assembly, a special grease is applied to the needle bearings. a few drops of oil or a special thick grease.
Device and principle of operation
The clutch basket of modern chainsaws is a successful and simple technical solution. It fully meets all the requirements for such a node:
- automatically, without special activation by the operator, transfers the torque from the engine to the chain gear at speeds above idle,
- does not move the chain at idle,
- protects the engine if the chain is jammed in the wood (the clutch slips, the engine does not stall or wedge).
- Centrifugal mechanism with springs.
- Outer cover with chain drive gear.
It is through the interaction of these nodes that the clutch is automatically activated when the speed rises.
Drum (top cover with gear), 2. Coupling, clutch disc (mechanism with springs), 3. bearing.
The centrifugal mechanism is attached to the threads of the crankshaft. At low (idle) speeds, it rotates without touching the driven outer cover with a gear. As the revs increase, centrifugal force moves the clutch segments apart. They press against the outer cover with the gear and begin to rotate it, engaging with it due to the frictional force. The chain starts to move.
When the speed decreases, the springs return (compress) the segments to their previous position, a gap appears between the cover and them, the chain stops.
Features of this design. wear of the segments of the centrifugal mechanism and the inner surface of the outer cover due to friction.
Wear is accelerated when erroneously switched on at high speeds with the safety brake engaged.
This also happens when the chain is frequently clamped in wood. In this case, the shaft rotates at high speeds. The segments are moved apart by centrifugal force and pressed against the inner surface of the outer cover. That is, the clutch is engaged in operating mode. At these speeds, the segments and the gear cover must rotate together, synchronously, and the chain must move. But on the brake and when the clutch slips, there is increased friction, overheating and wear between the segments and the inner side of the cover.
The space between the inside of the cover and the centrifugal mechanism must be clean. Ingress of dirt leads to incorrect operation. heavy chain movement, chain scrolling at low speeds.
This assembly contains needle bearings that require regular lubrication. The regulations for their maintenance, as well as the clutch in general, are spelled out in the operating instructions for each specific brand of chainsaw.
Chainsaws, for various reasons, need to be repaired from time to time. Of course, you can contact a service workshop or an experienced mechanic. However, many problems can be fixed at home with only a minimal set of skills and tools.
Answering the question of how to remove the clutch from a chainsaw, we note that this is not a difficult operation, if you adhere exactly to the disassembly technology. Owners of the tool may face certain difficulties if the chainsaw has been in use for a long time, and the clutch parts have become attached to each other.
When replacing the clutch, we do not recommend using metal or plastic objects as a stopper. The former can scratch the cylinder, the latter can litter it.
- Turn on the chain stop brake, remove the protective cover and dismantle the saw headset;
- We remove dirt, sawdust, dried grease, if any;
- Remove the air filter and candlestick;
- Using a candle wrench, unscrew the candle;
- Rotating the crankshaft, we bring the piston to the top point, then set it back by 6-9 mm;
- With a rope, 7-8 mm in diameter, we lock the piston in the upper position;
- Unscrew the nut on the clutch with a special puller wrench.
Most of the moving parts of a chainsaw are right-hand rotation. Therefore, the nut on the clutch has a left-hand thread. It is necessary to remove the cover by turning the key clockwise. It is forbidden to carry out this operation with a hammer and a chisel. you will knock down the edges!
- Remove the cover and drive sprocket. We diagnose faults and assess the wear of parts. Assessing the condition of the needle bearing;
- If necessary, we replace parts with new ones (most often the leading sprocket needs it);
The installation of the chainsaw clutch system is carried out in the reverse order, however, you should pay attention to some features.
Changing the sprocket on a Chinese chainsaw
How to remove
In order to remove and disassemble the clutch, you need to install the chainsaw on a flat, non-slip surface and secure it with fixing elements.
First you need to unscrew the saw chain and bar using the universal wrench. Then you can remove the cover from the air filter element. Then you need to remove the spark plugs, and fix the piston part in the master cylinder.
After that, install a suitable puller and unscrew the clutch.
After the actions taken, remove the clutch drum on the chainsaw and the clutch. At the end, you can conduct an external inspection of the system for damage and defects and, if necessary, replace the failed parts with new ones.
Clutch device, principle of operation
In order to successfully disassemble this unit, you will need a chainsaw clutch puller. But before we look at how to use it, we will study the features of the device of this functional part of the power unit.
Please note that when developing modern chainsaws, manufacturers most often resort to using a centrifugal clutch. And this suggests that the tool and its operation depend on the stock of torque that the equipment produces here and now.
The main structural details of this unit include:
- an asterisk;
As for the principle of work, everything is simple here.
Removing the clutch from a 45cc Chinese chainsaw (Baumr SX45)
- As soon as the chainsaw is switched to working mode, the clutch springs will pull all freely moving elements (move in the radial direction) towards the axis.
- At this moment, no torque will be transmitted to the sprocket guide.
- As soon as the centrifugal force rises above the force potential of the spring, all freely moving attracted elements will weaken and compress inside the drum, which will start it (it will start spinning).
- The rotation will transfer to the guide bar and main sprocket.
It is on this principle that the centrifugal clutch works, which has several advantages over its other varieties. Among them is the lack of engine stop when the cutting element is suddenly braked (that is, the clutch slips). Due to this feature of the mechanism, the main unit of the chainsaw remains unharmed.
Note that this type of clutch will work automatically. Its functioning depends on the number of revolutions of the engine. Moving elements inside the drum will be attracted to the shaft (its center) even at minimum RPM. This plays an important role in preventing serious tool breakage. When this mechanism fails, then it becomes necessary to figure out how to remove the clutch on a chainsaw.
The chainsaw device includes a clutch mechanism, which consists of elements such as:
- driven disc;
- pressure disk;
- protective cover of the mechanism;
- release lever;
- inclusion plug;
At minimum revolutions of the power unit, the chainsaw clutch is attracted to the center of the shaft by a spring device and does not transmit torque to the drum. At a time when the engine speed begins to reach indicators at which the breakout force exceeds the force of the spring device, the friction-type segments begin to press against the inner surface of the drum mechanism, which contributes to the rotation of the drum of the Chinese chainsaw.
During this, the drive type sprocket begins to rotate, which is responsible for the movement of the saw chain.
How to change
In order to replace this mechanism, it is necessary to dismantle the old hitch. During repair work, the saw must be securely fixed on a non-slip surface using special devices.
During the dismantling and installation of the clutch, it is recommended to take into account the following nuances of such work:
- On some versions of the tool, a washer is located between the hitch and the drive gear cup. Therefore, at the end of the repair, it is necessary to install this element in place.
- Some oil lines have a special spring. It is mounted between the sprocket and the oil pump drive. It also needs to be properly reinstalled after replacing the hitch.
Do-it-yourself repair of the chainsaw clutch is carried out only in special protective clothing: a mask and glasses.
Main malfunctions, their causes and remedies:
How to assemble
In order to assemble the mechanism back, it is necessary to install the clutch in place and fix it with a special handle. The saw motor must be turned off at this moment.
Then the spring device, drum mechanism and sprockets can be replaced.
Then you can install the clutch mechanism back into the tool body, remove the crankshaft from the stopper, install the filter mechanisms, the throttle valve and the step with the chain in place.
At the end of the work, it is recommended to start the chainsaw and check the performance of the assembled clutch. If all parts are installed correctly, the clutch will engage immediately, there will be no delays or leaks.