HMHG-Ⅱ-E Simple Unit (Flat & Integral Cam) Series Harmonic Gearing HMHG-II-E series flexspline is a hollow, hat-shaped standard structure, the whole structure is compact. The input shaft is connected to the wave generator's inner hole through an integral cam. power drive gearbox can adopt the connection mode with circular spline fixed and flexspline as the output end. And it also can adopt the connection mode with the flexspline fixed, the circular spline as the output end.