Power tool emergency stop system

摘要

A safety apparatus for a tool driven by a motor removes motor power under certain circumstances. The tool includes a housing moveable over a ground surface for mounting the tool, and a ground-engaging member moveable relative to the housing and disposed to follow the ground surface as the housing moves over same. The apparatus further includes a sensor for measuring the relative position of the housing relative to the ground engaging member. Motor control apparatus selectively stops the motor upon the ground-engaging member and the housing reaching a predetermined relative position.