How to change a pole saw sprocket
A little about the rules for operating 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 in the quality of the assembly or the manufacture of the components, but in the class of tasks performed, the performance and the continuous power of the drive. This predetermines the choice of the material of the leading sprocket for the chainsaw, its design and the design of the saw chain.
The performance of the tool will be determined by the way the chain-sprocket pair is operated. In most cases, users use one of two options:
- The chain is operated until the teeth are completely worn out, and then both the saw blade and the sprocket are replaced at the same time;
- Periodic replacement of chains with different pitch, and each will require its own drive sprocket.
The choice of option is often determined by the owner’s attitude to his instrument. If it doesn’t matter what to cut (wood or steel staples stuck in it, screws, etc.), then you can stop at the first option. The chain, however, will have to be adjusted periodically, thereby reducing the performance of the chainsaw.
It is strongly not recommended to leave the old chain with a new sprocket and vice versa. When the saw blade is worn out, the probability that the tooth pitch will not match is almost one hundred percent. Therefore, at the initial moment of starting, both components of the chain drive will be subjected to significant dynamic loads. As a result, either the chain will stretch prematurely, “adjusting” to the sprocket, or upon impact, one of the teeth on the drive sprocket will burst.
In addition, it is worth focusing on the operation of the bearing assembly of the drive sprocket shaft. When the saw is operating at working speed, only the crankshaft rotates. But all chainsaws periodically operate at idle speed when the bearing rotates. With a lack of lubrication, the wear of the seat occurs, and. as a result. additional beating of the teeth of the still fully functional chain transmission.
It follows from this that when replacing the chain and the drive sprocket for a chainsaw, it is a good idea to replace the bearing at the same time.
Why it is necessary to replace the drive sprocket
Among the most common reasons a tool may need to be repaired is the replacement of the drive sprocket. This part becomes unusable due to:
- jamming of the chain in the event of any defect during the operation of the equipment;
- high wear of the sprocket with prolonged use of the chainsaw.
Regular use of the tool contributes to increased wear on the part due to the increased stress when sawing wood materials. There are several known ways to use the tool:
- By using one chain saw.
- By alternately using several chain saws.
With the first method of using the tool, the saw is operated until it is completely worn out. This method has certain disadvantages, among which a problem can be noted when carrying out manipulations that control wear as a result of intensive operational actions.
When working with two or more chains, you can get even wear on each chain and sprocket, which will significantly extend the operation of the unit and reduce the need for frequent drum changes. In addition, it is important to keep in mind the condition of the bearing installed in the drum. The operation of this structural element occurs at any engine speed. In case of sprocket replacement, it is also important to take care of bearing and coupling replacement.
Untimely repairs contribute to the occurrence of increased vibration, which affects the increase in wear rates of parts that are installed in the engine of the device on the crankshaft axle shaft. The value of the limiting depth when the teeth of the sprockets are worn should not be more than 0.5 mm. Sprockets have twice the lifespan of chains. Therefore, it is recommended to use two chains.
When the resource of each chain is exhausted, it is necessary to simultaneously replace the chains and the drive sprocket.
“I’ve been sawing with a Chinese chainsaw for five years, there is a slight play of the sprocket, I think that because of this, large logs are very difficult for the saw. In the service center, they really can’t say anything, and I don’t know what kind of asterisk there should be, that is, what model to replace so that there is no backlash. The saw is still on the move, there are no other complaints “.
The main signs that the asterisk needs to be changed:
- on your chainsaw, the chain was replaced twice (one of the current rules for operating a chainsaw and a saw. with frequent and active use of the tool, after two changes of the chain, the drive sprocket should be replaced);
- the quality of sawing has worsened, the chain needs to be tightened more often;
- you installed a new chain, which does not fit the old drive sprocket (this part is not universal, and also has its own pitch, in addition, the steps of the drive and driven chain sprockets must match, otherwise the tool will not work);
- you are using a different bus, shorter or longer.
Chainsaw sprocket replacement video:
How to change a star on a chainsaw?
If the chain begins to vibrate even at low speeds, the chainsaw is operated for a long time without replacing parts. it is required
carry out diagnostics and, if necessary, change the components of the saw headset. For a planned replacement, you will need a new clutch drum or whisk, depending on the specific model, a basic set of tools:
- candle key;
- cable up to 15 cm long or piston stopper;
- factory key for removing the clutch;
- adjustable or wrench. Figure 3. Required tools for changing the star
It is recommended to have a round file, pliers, a vise and a knife to eliminate defects in the design from the chain set (if only tooth correction is required).
Algorithm for self-replacement of the clutch drum with an asterisk
How is the drive sprocket replaced on a saw or chainsaw. more on this in detail.
For the sprocket replacement procedure, you need to do the following:
- remove the chain brake cover and pull it towards you (avoid contact of the brake band with the clutch parts);
- using a wrench, loosen the nuts holding the chain tension and the chainsaw cover;
- remove the chain and then the bar, removing debris and sawdust from the holes for the fasteners;
- we fix the piston in the cylinder using a regular cord, but if possible, you need to use a piston stopper or a special lock;
- the clutch begins to rotate and do this until the piston touches the outlet;
- after which the stopper or lace is lowered into the candle opening and fixed there, tying several knots (the stopper will fix itself);
- unscrew the clutch nut (note. the thread of this nut is left-handed, take this into account when unscrewing);
- it is forbidden to use hard tools so as not to break the soft metal of the clutch nut;
- then the clutch is removed;
- then remove the sprocket gear itself;
- replace the old asterisk with a new one;
- assemble the structure in reverse order.
Types of stars
Depending on the class of the chainsaw, all the stars are divided into two groups. professional and household. The first type of parts have increased wear resistance, are made of strong metal alloys that are not subject to corrosion and mechanical damage. Households often require replacement and scheduled repairs; with active use of the tool, diagnostics are recommended every six months. By design features, the following types of asterisks can be distinguished:
- National teams. The removable ring can be easily unscrewed from the drum axis, which makes it easy to check and replace this part. Almost all European models of chainsaws are equipped with such stars.
- Whole. They consist of a hub and a stationary crown (the number of teeth may be different, you need to carefully read the instructions for the chainsaw). Due to the factory pressing, the crown cannot be removed separately from the hub, therefore, in case of a breakdown, the entire clutch drum must be disassembled. Such a mechanism is usually found on Chinese models.
If you plan to service the chainsaw on your own, then it is recommended to purchase a tool with a professional type of drive sprocket. It should be collapsible, which reduces the cost of repair and maintenance of the tool.
How to assemble?
The assembly of the coupling mechanism should be carried out in the reverse order. First, install the sprocket on the needle bearing, then put on the drum, washer, gasket and the clutch itself. Tighten counterclockwise, lightly fix the piston.
If your chainsaw has an oil drive spring, it can be built into the drive sprocket. In most models, the correct position of this element is marked with a special color or notch. To get to the desired position, turn the sprocket until it clicks.
The last step in the assembly is to install the guide bar. During this process, it is required to release the handbrake, and then check that the chain teeth fit into the corresponding grooves. After installation, mount the chainsaw chain until it is operational. Finally, remove the stopper, screw in the spark plug and replace the filter. The final step of the repair is to secure the protective cover of the case.
How to remove a sprocket from a chainsaw: several options for different clutch drum designs
How to remove an asterisk from a chainsaw. detailed description
Removing an asterisk
With the piston stationary, turn the clutch scale clockwise to loosen it. The clutch weight is the piece of metal inside the rim facing you. Once you remove the clutch weights, you can pull on the drive rim and sprocket behind it and replace one or both of them with new parts. The small ribbed cylinder remaining on the output shaft is a needle bearing. Check this part for wear when replacing the drive sprocket. Husqvarna recommends lubricating the needle cage weekly.
Chainsaw sprocket and its functions
Before you figure out how to change the sprocket on a chainsaw, it is worth understanding how the sprockets look and the problems associated with them. Sprockets have star-shaped teeth that guide the chain outside the sprocket for smooth operation. Sprockets: Sprockets have a rim that moves freely around the spline to guide the chain around the internally-toothed bar.
Drive sprocket. This is a very important and often overlooked part of chainsaw maintenance. The sprockets are sized according to the length of the chain you are using. They should be changed every 2-3 times the chain is replaced. Try to determine which rim or sprocket you have. Fitting a rim and sprocket means it is easier and cheaper to change the rim, which is the part that drives the chain. They wear out faster, but they are cheaper. The bezel must be replaced if worn by 0.2 mm.
Replacing A Drive Sprocket (Stihl Chainsaw)
Changing the rim on Stihl chains is easy. On chainsaws where the rim is inside the clutch, such as some Husqvarnas chainsaws, you must first remove the clutch.
The spindle sprockets drive the chain directly from the star-shaped teeth on the sprocket itself. When they are worn out, the entire sprocket must be replaced. They tend to wear out more slowly, but are more expensive when you replace them.
Side sprockets and rear clutch sprockets are easy to change. Removing the integral sprockets is more difficult as the clutch assembly must be removed first. This requires you to remove the spark plug and turn on the piston stop tool.
If you keep using a worn sprocket, it will start to damage the drive links, which in turn widen the groove in the groove, which then gives a poor cut, which further accelerates the wear of all parts! This is especially problematic for longer rods.
Sometimes the bearing on the sprocket needs to be replaced. This is a simple case of removing the sprocket, extending the existing bearing and replacing it with a new one.
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.
The chain sprocket guides the chain in a continuous motion along the bar. Sprockets can be worn, chipped, or damaged due to high stress, friction and normal wear. If the sprocket is damaged or worn out, the chain may slip, break off the sprocket, causing the chain not to rotate at all. Decreased chainsaw performance can also mean sprockets need to be replaced.
It is useful for each owner of such a tool to know how to remove the sprocket from the chainsaw correctly and replace it. DIY repair saves both time and money. And also quickly bring the tool into working order, because for this you do not need to wait for an appointment at the service, it is enough to purchase the necessary parts.
Chainsaw drive sprocket classification
The main difference between them is the frequency of replacement and the rate of wear: in models of the “Profi” series, wear is faster, and repairs are more frequent.
By design features, the leading chainsaw sprockets are:
The latter consist of a hub with a stationary rim of a certain number of teeth. Their factory pressing does not allow removing the crown separately from the hub. This situation is typical for many Chinese chainsaws, for example, from the “Champion” brand.
The case with prefabricated sprockets is simpler: the removable crown is quickly unscrewed from the drum axis, so the repair does not cause any particular difficulties. This option is the advantage of most European saws, for example Stihl or Husqvarna.