How does an 'inertial' chain-brake work?

[Skooks]

Hi all:

How does an 'inertial' chain-brake (specifically on a Stihl) work? I have my 026 apart right now and am just curious how the brake is supposed to operate without hitting the hand-guard/brake control?

Thanks,

Skooks.

 

[windthrown]

Chain brake

Inertia brake vs the hand lever brake? They use the same braking system, the metal band around drum. They are activated differently. The inertial brake is activated if the saw moves fast enough in a kichback motion. The force of kickback triggers the brake by releasing the catch latch which activates the brake by a spring. The brake is reset/released for both activation methods in the same motion by pulling the brake lever backward.

 

[Lakeside53]

It's activated by a sudden upwards movement of the saw. The brake handle opposes this force (it's "hinged") and activates.