What is a Chainsaw Sprocket?

The chain sprocket drives the chain, hidden behind the sprocket cover. Made from wear-resistant steel, it transmits power from the engine to the chain loop. The teeth of the sprocket engage with the link tanks, causing the saw to rotate. Drive sprockets must match the saw's pitch, which is usually stamped onto the sprocket.

Sprocket Types:

Spur

A spur chain sprocket is a standard component soldered to the clutch drum, typically shaped like a star. It usually has between 6 and 8 teeth, with the drive links fitting between them to drive the chain.

Rim

A rim sprocket is mounted on the clutch drum hub. The chain links fit into the rim, which drives the chain. Rim sprockets typically have 6 to 8 points, and when worn (usually 0.02mm), they can be replaced easily compared to changing the entire sprocket.

(This depends on your machine and whether it can accommodate both types.)

What can happen when the Sprocket is worn?

The sprocket should be replaced after 2 to 3 chains. Continuing to use a worn sprocket can damage the drive links and widen the bar groove, reducing cutting performance. This can lead to further issues with other components, turning a simple job into an expensive repair.

Stihl recommends regularly checking the chain sprocket's condition with a control gauge. If the wear marks reach about 0.5mm, the sprocket must be replaced.

Stihl Wear Control Gauge - 0000 893 4101»

Why are there different amounts of teeth on sprockets?

Changing the number of teeth on your chainsaw’s drive sprocket alters its performance, known as gearing. This applies to both spur and rim sprockets, though it is easier with rim sprockets due to their design. It's best to stick with the factory tooth count for your chainsaw.

Spur Sprocket

Rim Sprocket

Gearing Examples:

• More speed requires a higher tooth count.
• More strength requires a lower tooth count.

Both factors need to consider chain gauge and bar length.

(The best tip is to maintain your chainsaw and follow the manufacturer's recommendations.)

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