Safety braking apparatus for portable chain saw

摘要

A chain saw having an improved safety brake actuating mechanism is provided. The actuating mechanism includes a safety lever pivotally mounted on the chain saw housing for movement from an operating position to a braking position in which a brake band is brought into frictional engagement with motive means which drives a cutting chain. A latching member is pivotally mounted on the safety lever for releasable latching engagement with the housing. A spring member engaged intermediate the housing and the latching member exerts a yieldable force on the safety lever which constantly biases the safety lever for movement from the operating position to the braking position while also exerting a yielding latching force on the latching member. The spring member cooperates with the safety lever for holding the latching member in releasable latching engagement with the housing and for resisting movement of the safety lever thereby preventing inadvertent frictional engagement of the brake band with the motive means when the lever is in the operating position. The spring member is cooperatively engaged with the safety lever for permitting rotation and disengagement of the latching member from the housing as the safety lever rotates from the operating position to the braking position in response to an actuating force acting on the safety lever.