Abstract: The power tool is equipped with a radar for transmitting radio waves towards an area in a vicinity of a rotating tool and for receiving reflected radio waves reflected from a radio wave reflector existing within the area. From the reflected radio waves received by the radar, a distance between the radio wave reflector and the radar, and a speed of change of that distance are calculated. When the calculated distance and speed fulfill a first criterion, a first brake for applying gentle braking to the rotating tool is activated. When the radio wave reflector further approaches to the rotating tool and the calculated distance and speed fulfill a second criterion, a second brake for applying rapid braking to the rotating tool is activated. Distance in the first criterion and the increase as speed increases, and distance corresponding to a certain speed in the first criterion is longer than distance corresponding to the same speed in the second criterion.

Abstract: The power tool is equipped with a radar for transmitting radio waves towards an area in a vicinity of a rotating tool and for receiving reflected radio waves reflected from a radio wave reflector existing within the area. From the reflected radio waves received by the radar, a distance between the radio wave reflector and the radar, and a speed of change of that distance are calculated. When the calculated distance and speed fulfill a first criterion, a first brake for applying gentle braking to the rotating tool is activated. When the radio wave reflector further approaches to the rotating tool and the calculated distance and speed fulfill a second criterion, a second brake for applying rapid braking to the rotating tool is activated. Distance in the first criterion and the increase as speed increases, and distance corresponding to a certain speed in the first criterion is longer than distance corresponding to the same speed in the second criterion.