HST-I harmonic drive reducer manufacturer tells you that like planetary gear transmission, harmonic gear transmission is also composed of three basic components. HST-I harmonic drive reducer manufacturer tells you that they are the fixed inner-toothed spline and flex spline respectively (that is, the elastic thin-walled sleeve cup whose base is connected to the driven shaft "make the ring gear on the generatrix at the beginning of the flex spline") ) and a wave generator for radially deforming the flex spline.

HST-I harmonic drive reducer manufacturer tells you that on the rigid spline and the flexible spline, cut out the same modulus of teeth, but the number of teeth is different, that is, the number of teeth of the flexible spline is two less than that of the rigid spline. The tooth number difference of the harmonic drive represents the deformation wave number of the flex spline. 
HST-I harmonic drive reducer manufacturer tells you that the most common is the harmonic drive with wave number w-2. In the free state (no generator), the two wheels are in the concentric position, and the gap between the teeth of the rigid wheel and the flexible wheel is uniform.
Through the above introduction and analysis of the Working principle of HST-I harmonic drive reducer, hope it helps you.