Why Chain Flies On A Saw

When and why do I need a replacement for a worn chainsaw sprocket

The drive chain sprocket or chain saw is one of the most important parts of the saw. The main function of the chainsaw sprocket is to transmit engine torque to the saw chain. This transmission is through a centrifugal clutch. By type of sprocket, can be divided into professional and household, as well as chains. During operation of the chainsaw and sawing wood, the drive sprocket, like the chain, gradually wears out.

Why Chain Flies On A Saw

Let’s find out in more detail why the replacement of a worn chain saw or chain saw sprocket is necessary and when it is better to perform such a change.

The main signs that an asterisk need to be changed:

  • the chain was replaced twice on your chainsaw (one of the operating rules for operating the chainsaw and saw is that with frequent and active operation of the tool, after two chain changes, the drive sprocket should be replaced);
  • sawing quality deteriorated, the chain began to need to be pulled more often;
  • you have installed a new chain that the old drive sprocket does not fit (this part is not universal, and also has its own step, in addition, the steps of the drive and driven chain sprockets must match, otherwise the tool will not work);
  • You are using another bus, shorter or longer.

Video about replacing asterisks on a chainsaw:

Why replace an asterisk?

Remove a worn star for the following reasons:

  • with an old asterisk, the saw chain will stretch very quickly. after several applications the chain will hang, and the tension will not help;
  • if you put a new chain on an old sprocket, the smoothness of the chain will decrease, the cut quality will deteriorate, the chain will lead to the side when cutting;
  • general wear of the chainsaw will accelerate, the tool may fail at any time;
  • the chain may break or the chain will jam during operation (dangerous by injuries to the hands and damage to the saw body, chainsaw);
  • the tire will heat up faster, which will lead to quick overheating of the chainsaw;
  • The load on the engine and housing will increase.

Important! Do not replace at your own discretion the size of the sprockets during repair, use the manufacturer’s standard. Unauthorized replacement will lead to a deterioration in the performance of the chainsaw or saw.

Video on how to change an asterisk on a chainsaw:

Are there any ways to extend the life of an existing star?

The main ways to extend the working life of the leading chain saw sprocket:

  • use multiple chains (preferably three). This method is the most gentle and convenient for the owner of the chainsaw in that you do not need to constantly tighten the chain worn out by intensive work. Operation of three circuits in turn will save the sprocket’s life and delay its replacement;
  • high-quality maintenance of the drive sprocket bearing. This part plays an important role in the operation of both the drive sprocket and the engine. A special lubricant is recommended for lubrication. The sprocket bearing is not always activated, but only at idle, therefore, it needs periodic lubrication. You can use tire grease, such as standard grease from Repsol or Husqvarna.

Video: Why Chain Flies On A Saw

Is it wise to try to fix or sharpen an asterisk?

The cost of this spare part is small, and an independent repair or attempt to restore a worn part never leads to efficient operation of the chainsaw. It is recommended to replace the part with a new one with signs of wear.

How to unscrew an asterisk on a chainsaw:

What tools are needed to replace the sprocket

To replace the drive (drive) sprocket, you will need such tools and accessories:

  • a special key for removing this part (usually supplied with expensive branded chainsaws, cheap saws are not equipped with such a key);
  • drift from aluminum or copper (only from soft metals and only in the absence of a key);
  • hammer (for striking a punch in the process of unscrewing the sprocket);
  • flat screwdriver for tightening the nut;
  • grease for sprocket bearing.

Construction problems, differences between different models

Branded chainsaws have a special design that does not allow replacing a worn-out drive without removing the clutch and other parts of the chainsaw. That is, the saw needs to be almost completely disassembled. modern models of expensive chainsaws are always equipped with a special key.

Also, the owner of the chainsaw may encounter such a nuance: on Chinese imported chainsaws or saws, the asterisk on the clutch mechanism can be located in an unusual way. On older models, when the teeth of the chain are worn, you need to unscrew and change the drum, one-piece with a drive. On newer models, you can replace the sprocket separately.

Algorithm for self-changing drum clutch with sprocket

How are the leading sprockets replaced on a saw or chainsaw. more on this in more detail.

For the sprocket replacement procedure, you need to do the following:

  • remove the chain brake cover and pull it towards you (avoid contacting the brake band with the clutch parts);
  • using a wrench, loosen the nuts that hold the chain tension and the chainsaw cover;
  • remove the chain and then the tire by removing debris and sawdust from the mounting holes;
  • we fix the piston in the cylinder using a normal lace, but if possible, use a piston stop or a special clamp;
  • the clutch begins to rotate and do so until the piston touches the outlet;
  • after which the stopper or cord 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, take this into account when unscrewing);
  • hard tools must not be used so as not to break the soft metal clutch nuts;
  • then the clutch is removed;
  • after they remove the pinion gear itself;
  • replace the old sprocket with a new one;
  • reverse the assembly of the structure.

Video about replacing asterisks on a chainsaw or saw


Anatoly, Zhytomyr:

“I’ve been sawing a Chinese chainsaw for five years, there’s a slight backlash in the sprocket, I think that because of this, large logs are given to saw very hard. The service center can’t really say anything, and I don’t know which star there should be, that is, which model to replace so that there is no play. Saw while on the move, no other complaints. "