Abstract

A portable power tool includes a manually actuable safety lever and an inertial safety system for activating a brake of the tool to provide a more effective safety arrangement. A first spring applies the brake when the safety lever contacts the hand, wrist or arm of an operator during "kick-back" or like violent movement of the tool. A second spring is operable independently of the safety lever for also releasing the first spring. An inertia mass is displaceable effectively independently of the safety lever when the brake is in the inoperative condition. This inertia mass releases the second spring, so releasing the first spring and applying the brake, upon occurrence of "kick-back" or the like. Preferably, the second spring operates a hammer release mechanism for striking a locking lever releasably retaining the safety lever. A band brake of a chain saw or circular saw may particularly be operated in this manner.