The helicopter flapping rotor wing blade speed-change gear box consists of casing, driving shaft, driving shafts, output shaft, driving elliptic gear, driven elliptic gears, large cone gear and small cone gear. The driving shaft and four driven shafts are fixed on the box body respectively by means of bearing, and the driving elliptic gear and four driven elliptic gears are respectively eccentrically fixed on the driving shaft and four driven shafts, the driving elliptic gear is respectively meshed with four driven elliptic gears, on four driven shafts the large cone gear is set and meshed with small cone gear fixed on the output shaft on the casing, because the rotating speed outputted by gear box is changed, so that it can make the wing automatically balance the influence of air stream on helicopter. |