Patent ID: 6393837
Filing Date: 2002-05-28
Classification: B24B,F01B

Abstract:
An air tool with a safety device comprising:a main body casing; an air passage in said main body casing; an air motor rotated by air supplied through said air passage; a valve seat in said air passage; a safety valve body movable toward and away from said valve seat to change an effective opening of said air passage; first urging means for urging said safety valve body in a direction to ward said valve seat; a rotary member rotating with an output shaft of said air motor; a safety valve stopper connected to said rotary member; said safety valve stopper being displaceable outward in a diametrical direction by a centrifugal force generated by a rotation of said rotary member; second urging means for urging said safety valve stopper in a direction opposite to a direction in which said centrifugal force is applied; a lock mechanism for locking a motion of said safety valve body during steady operation; said first urging means urging said safety valve body away from said valve seat thereby moving said safety valve body away from said valve seat against an urging force of said first urging means thereby increasing an effective opening of said passage, disengaging said lock so as to move said safety valve body in a direction closer to said valve seat by said first urging means, thereby reducing said effective opening of said passage when a rotation rate of said output shaft of said air motor exceeds a predetermined value and said safety valve stopper moves against said urging force of said second urging means due to centrifugal force, and again locking motion of said safety valve body in this state between said safety valve body and said safety valve stopper.