How to remove the drive sprocket from a Husqvarna, Partner, STIHL, Champion chainsaw
With regular use of many tools, it is necessary to periodically replace their consumable parts. In this connection, it is necessary to know how to remove the sprocket from a chainsaw correctly in order not to spoil the tool.
This part is also called the centrifugal mechanism or clutch disc. For a better understanding of the whole process, it is necessary to understand what is a sprocket and how it is used.
Replacing the drive sprocket on a Chinese chainsaw
There are almost no fundamental differences in the design of Chinese chain saws, which means that this method of sprocket replacement will suit almost any model of chain saw of Chinese origin.
Disassembling a Chinese saw to change the sprocket
The first thing to do to replace the chainsaw drive sprocket. unscrew the bolts on the side cover of the chainsaw body and then remove the cover. Next, you need to remove the top cover to access the spark plug.
Remove the air filter and unscrew the spark plug. Rotate the chainsaw clutch clockwise until a cavity is formed in the hole where the spark plug was located, which can fix the piston in the dead center. If you do not have a special metal stopper for the piston. use rope or cord to hold the piston in place.
If you have a metal stopper. be careful not to scratch the piston. After you install the stopper, use a wrench to unscrew the clutch cover. Remove the washer and the clutch plate. Next, simply remove the old drive sprocket.
How to reassemble the chainsaw after replacing the drive sprocket
After replacing the sprocket, the chainsaw must be reassembled. Reassemble in reverse order. Install the drive sprocket, put the sealing washer on top if there was one, cover the whole construction with the clutch and screw it on. Install the chainsaw side cover and tighten the necessary bolts.
How to extend sprocket life
In practice to have even wear of sprocket rim a set of several chains of the same type is used that are alternately replaced as cutting edges of saw links become blunt. Nevertheless, sooner or later the user is faced with the need to replace the worn-out part.
The wish of the owner to complete the set with a saw chain of a different pitch leads to the necessity to change the sprocket for the part with a corresponding profile ring. This requirement is valid for the whole assortment of chainsaws made in Europe and China.
Operating reliability of a European-made chainsaw, when working under severe conditions of heavy loads, may be considerably impaired if a sprocket made in China is used instead of a brand-name sprocket.
Reasons for failure and how to determine if it needs to be replaced
The cams are compressed by the spring when idling and do not touch the drum. If the speed increases, the centrifugal force exceeds the stiffness of the spring and the cams come into contact with the drum walls. The last one starts to rotate.
saw chain teeth are in contact with the teeth of the drive sprocket. One of the automatic centrifugal clutch’s functions is to protect the engine when the chain load exceeds the allowable limit. This can occur when the chain is jammed.
The outside of the drum is encircled by the emergency brake band. When the handle is folded back, the belt is pressing against the drum and stopping it from spinning. The effect is the same as a jammed chain.
A feature of all chainsaws is that the clutch drum and cams are attached to the shaft with a nut with a left-hand thread to prevent the mechanism from unscrewing during operation.
Wear on the teeth of the drive sprocket can occur for several reasons
- Natural wear along with the chain teeth;
- accelerated wear as a result of excessive tension or lack of chain lubrication;
- Improperly selected chain;
- manufacturing defect.
Metal wear can be determined visually by examining the sprocket without removing it from the saw. Dents and chips on the surface must not exceed 0.5 mm.
Need for replacement is indicated by excessive noise in the chain, but only if the chain has a deep defect. A shallow strikeout is difficult to see during operation, but will cause severe wear on the chain. If the chain breaks its teeth, it can move jerkily, which is particularly noticeable during operation.
The clutch is engaged automatically depending on the number of revolutions of the motor.
The units are fitted with a centrifugal clutch that runs automatically, depending on the number of revolutions of the motor.
When the engine is running at idle or low RPM, the friction liners in the clutch basket have a certain amount of freedom in a circular pattern. The freedom of movement causes the elements to be drawn to the center of the rotary shaft by the action of the springs and does not produce any rotary motion to the sprocket drum.
As the machine motor rpm increases, the centrifugal force exceeds the force of the springs, resulting in displacement of the parts with friction linings. Replacing the piston on a Chinese chainsaw. Replacement piston group of chinese chainsaw 4500replacement piston group of chainsaw 4500 cylinder piston group for chainsaw 45mm replacement piston group on STIHL ms180 chainsaw china replacement.
Sprocket replacement on how to unscrew the clutch on a chainsaw. On a Chinese chainsaw. These elements are pressed against the inner walls of the drum by centrifugal force. this contact results in rotational motion to the drum and sprocket that drive the saw chain of the tool.
frequent causes that force the repair of the tool, associated with the replacement of the drive sprocket are:
- Chain jamming due to flaws in the machine’s operation;
- High wear of the sprocket as a result of long-term operation of the machine.
the first two models differ in wear frequency and wear rate: “heavy duty” models wear faster and repair more often.
The sprocket consists of a hub with a stationary ring consisting of a determined number of teeth. Their factory press fit prevents them from removing the sprocket separately from the hub. This situation is typical for many Chinese chainsaws, for example, from the brand “Champion”.
The case with prefabricated sprockets is easier: the removable crown is quickly enough unscrewed from the drum axle, so the repair does not cause much difficulty. This is an advantage of many saws of European origin, like STIHL or Husqvarna.
According to the peculiarities of design, pinions are divided into:
- One-piece. The part includes a hub, into which the ring gear is pressed. The entire part can only be removed for replacement. In the industrial environment of the manufacturer, it is possible to ensure the design values of the interference. This is done with special equipment. This is not possible in the back-end of the production line. Difficulties also arise when trying to buy the ring gear separately. the manufacturer does not consider it an independent part and does not supply it to stores and service centers.
- Assembled. The ring gear is made as a separate part, and can be removed with a special puller or special tricks with a universal tool.
Specialists identify the following signs of drive pinion tooth wear:
- At the base of the tine are noticeable semicircular depressions;
- the thickness of the sprocket varies with height;
- chipped areas on the apex;
- There are scratches inside the hub bore;
- the chain has rubbed the groove on the sprocket;
- the chainsaw becomes wedged on startup.
chain saw chainwheel with such signs should not be operated, it must be removed and replaced.
According to the manufacturer’s recommendations, the tool should be inspected before starting work. Always check that the guide bar is in good condition and is securely fastened. If the screw that regulates the position of the chain roller and its tensioning is loose, or if the nuts that hold the bar to the body are loosened, the bar is deflected from the plane of the chain.
Sprockets with interchangeable and stationary ring
After tightening fasteners and adjustments do a test run. If it is still stuck, the sprocket has to be removed and replaced.
Husqvarna 137 chain saw is a semi-professional amateur tool. The model has achieved high popularity among consumers due to its good performance indicators, low weight and versatility. These days the Husqvarna 137 chain saw is actively used not only by gardeners, but also by employees of utility companies.
Design problems and differences between different models
The uniqueness of electric saws and chainsaws from leading manufacturers is that they have a special design. To change the transmission, you need to disassemble the clutch and surrounding components. In fact, the saw has to be completely disassembled. To enable the owner to disassemble the saw himself, a special wrench is sold with it.
Chinese models differ slightly from their European counterparts in that the sprockets are arranged slightly differently. In models of earlier years of production, it was necessary to change the drum with the drive, but in modern chainsaws, the change of the gear is much easier.
Features of saw designs
STIHL professional chainsaw
There are already in use several dozen chainsaws from different manufacturers, capacities, and most importantly special purpose. Divide saws into:
Accordingly, the drive gear in them will be different, as well as the sequence of actions. This is a feature of the devices of saw gearboxes. Most professional tools have a guide bar that can be repositioned on the saw in two planes.
You may also be interested in the article, chainsaw chain sharpening with their own hands.
The main chainsaw malfunctions and troubleshooting actions are described here.
Sprocket for Husqvarna chainsaws 40, 45, rasp.
Applied in chain saws: Husqvarna 40, 45 chain sprocket, which is a plate with meshed.
the product is in stock at the supplier, we can send within 2-3 days, to confirm the order requires prepayment
A little about the rules of the node
Regardless of the brand manufacturer (Shtil, Husqvarna, Partner, Patriot, Makita) chainsaws are divided into home, semi-professional and professional. The difference, however, is not in the quality of assembly or workmanship of the components, but in the class of the tasks to be performed, the performance and the long term power of the drive. This determines the choice of sprocket material for the chainsaw, its design, and the design of the saw chain.
Replacing the chain sprocket on a Stihl chainsaw
The performance of the tool will be determined by how the sprocket chain works. In most cases, users use one of the two options:
- The chain works until the teeth are completely worn, and then both the saw blade and sprocket are replaced at the same time;
- Periodic replacement of the chain, which has a different pitch, and each chain will require its own sprocket.
The choice of option is often determined by the owner’s attitude toward his tool. If it’s still sawing (wood or stuck steel staples, screws, etc. Д.), then you can go with the first option. However, the chain will have to be adjusted periodically, thereby reducing the performance of the chainsaw.
It is strictly recommended not to leave the old chain with the new sprocket and vice versa. When the saw is worn, there is almost a 100% chance that the tooth pitch is out of alignment. Therefore, both components of the chain drive will be subjected to considerable dynamic loads at the initial start-up. As a result, either the chain stretches prematurely, “adjusting” to the sprocket, or if one of the teeth on the drive sprocket breaks.
It is also worth paying attention to the operation of the sprocket shaft bearing assembly. When the saw is running at operating speed, only the crankshaft rotates. But all chainsaws periodically run and idle when the bearing rotates. In the absence of lubrication, seat wear occurs and, as a result, additional tooth beating is still a workable chainring.