Patent ID: 8297374

Claim:
A rotationally driven air tool comprising: an air motor having a rotational output shaft; a rotation transmitting mechanism comprising a gear rotated by rotational driving force received from the rotational output shaft to transmit the rotational driving force to a rotary tool member; and a housing comprising a motor chamber accommodating the air motor, a rotation transmitting chamber accommodating the rotation transmitting mechanism, a partition between the motor chamber and the rotation transmitting chamber, and an air blow port provided to extend through the partition to blow at least a part of air discharged from the air motor toward a peripheral wall surface of the rotation transmitting chamber that is substantially circular cylindrical around the gear, wherein the air blow port is configured to blow air in a direction substantially tangential to the peripheral wall surface around the gear; wherein the gear is a bevel gear, which is meshed with a bevel gear attached to the rotational output shaft, and a peripheral wall defining the rotation transmitting chamber is provided with an air discharge port for discharging air from the rotation transmitting chamber to an outside; wherein the bevel gear of the rotation transmitting mechanism comprises a circular cylindrical peripheral surface and a conical surface contiguously extending from the circular cylindrical peripheral surface and provided with a plurality of teeth, and the peripheral wall surface of the rotation transmitting chamber is set concentrically with the circular cylindrical peripheral surface of the bevel gear, and wherein the opening ends of the air blow port and the air discharge port open on the peripheral wall surface at positions respectively corresponding to the conical surface and circular cylindrical peripheral surface of the bevel gear in the axial direction of the bevel gear.