Air motor operated rotary earth drilling tool

A new and improved air motor operated rotary earth drilling tool for use with a source of high pressure, high volume compressed air has a circulation control housing, a motor housing, a reduction gear housing, and a bearing housing connected longitudinally in series. The circulation control housing is connected to high pressure, high volume, compressed air and has an outlet opening into the motor housing, and an exhaust opening for discharge of compressed air for flushing cuttings and debris from a bore hole which is controlled by longitudinal movement of an inlet tube. The motor housing has a motor chamber and a sliding vane rotor with a rotary shaft extending into the reduction gear housing. A planetary reduction gear receives the rotor shaft and has a low speed, high torque output shaft extending into the bearing housing. A passageway conducts compressed air around the planetary reduction gear for cooling. A radial and thrust bearing pack in the bearing housing is connected to the planetary reduction gear output shaft. A hollow, rotary drill bit sub extends into the bearing housing and is supported on the bearing pack for rotation by the planetary reduction gear. Part of the compressed air operating the motor and cooling the planetary reduction gear is discharged through the drill bit sub and part flows though the bearing pack for cooling and discharge into the bore hole.