A noncircular face gear (NFG) conjugated with a pinion is a new type of face gear which can transmit variable velocity ratio and in which two time-varying excitations exist. namely the meshing stiffness excitation and instantaneous center excitation. Considering the tooth backlash. static transmission error and multifrequency parametric excitation. https://allfixelectricales.shop/product-category/lid-hinge/