The harmonic gear drive invented by an American inventor, C· W· Musser,. usser in 1955, It is a new type of transmission, which uses the elastic defor mation of flexible components for motion or power transmission. It breaks through the mode of using the rigid component to realize mechanical drive, but with a flexible component instead, thus obtaining a series of special functions that other transmission cannot reach. Its name comes from the deformation process of the intermediate flexible component, which is a symmetrical harmonic. Except that the former Soviet. Union called this kind of transmission"Wave Transmission" or "Flexible Gear Drive", other countries like America, England, Ger many, and Japan all called it "Harmonic Drive’’.