The clutch on a chainsaw is of a centrifugal type, so that as the engine spins the clutch weights move out and engage with the inside of the sprocket.
Although there is little maintenance to do to a clutch, read on after the jump to find out a little bit more about the different clutch types...
- Inboard clutch.
- Outboard clutch.
The image to the right shows an example of an inboard clutch as used on Stihl machines, and by Poulan as well, I think - although that's a US-based make rather than UK (interestingly enough Poulan is owned by Husqvarna, who mainly use outboard clutches on their own machines!). This clutch configuration has one great advantage - it's extremely easy to remove / replace the sprocket should you need to.
Outboard clutches, as seen in the picture on the left, are commonly used in Husqvarna and Partner saws, and Stihl climbing saws. This type of clutch makes removal of the drive sprocket much more awkward, but assessing the state of the chain brake band is made much easier.
In the next few posts we'll take a look at the drive sprockets, before returning to check out the clutch weights.