Chain brake

Updated 2026-08-24 · Read this page as Markdown

A safety device that stops the chain almost instantly by clamping a steel band around the clutch drum. It is triggered either by pushing the front hand guard forward or, on inertia-activated saws, automatically by the sudden rotation of a kickback.

The chain brake is the single most important safety feature on a chainsaw and the one most often neglected: it collects sawdust and pitch, and a brake that has not been cleaned or tested can fail to engage when it matters. Test it before every session by running the saw at part throttle on the ground and flicking the guard forward — the chain must stop immediately. Engage the brake whenever you take more than a step with the saw running, and always before starting it. A manual-only brake will not save you from kickback if your hand is thrown clear of the guard, which is why inertia activation exists.

Related terms

Anti-vibration system The set of rubber buffers or steel springs that separate the engine unit from the handles, reducing the vibration transmitted to the operator's hands. Its effectiveness is what the declared front and rear handle vibration figures measure. Chainsaw chaps and PPE The personal protective equipment worn for chainsaw work: cut-resistant leg protection (chaps or trousers), a helmet with face screen and ear defenders, gloves and steel-toed boots. Cut-resistant garments contain long loose fibres that pull out, jam the drive sprocket and stall the chain on contact. Kickback The violent upward and backward rotation of the guide bar towards the operator, caused when the upper quadrant of the bar nose — the kickback zone — contacts wood, or when the chain is pinched in the top of the cut. It is the leading cause of serious chainsaw injuries. Sound Power Level The total acoustic energy the machine radiates in all directions, in dB(A), independent of where the listener stands. In the EU the guaranteed sound power level is the value that must appear on the machine's noise label. Sound Pressure Level The A-weighted noise level measured at the operator's ear position, in dB(A). It is the figure that describes what the person holding the saw is actually exposed to. Vibration Front Handle The vibration transmitted to the operator's hand at the front handle, expressed as an acceleration in m/s². It is one of the two figures used to estimate daily hand-arm vibration exposure.

Chain brake

Related terms

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