Patent ID: 7784731

Claim:
A transmission device for a twin-rotor helicopter, comprising: a transmission shaft of the twin-rotor helicopter defining a shaft axis and having a first shaft section, a second shaft section that extends from said first shaft section along the shaft axis, and a gear mounting portion that is mounted on said first shaft section, that is disposed adjacent to said second shaft section, and that extends in radial outward directions from said first shaft section relative to the shaft axis; a first tube sleeved rotatably on said first shaft section, and including a tube body and an annular portion that extends in radial outward directions from said tube body relative to the shaft axis; a second tube sleeved on said second shaft section such that said gear mounting portion is disposed between said first and second tubes; a plurality of first planetary bevel gears mounted rotatably on said gear mounting portion and angularly spaced apart from each other; a plurality of second planetary bevel gears mounted rotatably on said annular portion and angularly spaced apart from each other; a transmission gear disposed rotatably on said tube body of said first tube and disposed between said gear mounting portion and said annular portion, said transmission gear including a first bevel gear portion that meshes with said first planetary bevel gears, and a second bevel gear portion that is opposite to said first bevel gear portion and that meshes with said second planetary bevel gears; and a first output bevel gear that is disposed rotatably on said second tube adjacent to said gear mounting portion and that meshes with said first planetary bevel gears; and a second output bevel gear that is disposed rotatably on said tube body of said first tube adjacent to said annular portion and that meshes with said second planetary bevel gears.