The eccentricity ε determines the variation range of the transmission ratio of the reducer variable speed integrated gear. The larger the ε is, the more likely the gear teeth will have undercutting or top cutting defects. Therefore, in this example, the value of ε is [0,0.4]. When ε = 0, the non-circular gear will become the ordinary circular gear. The curve of response peak to peak PPV versus eccentricity ε is given in the figure. With the increase of eccentricity, the peak to peak value of gear dynamic response increases approximately linearly, which indicates that the time-varying transient center excitation will lead to greater vibration of non-circular face gear than that of circular face gear. This conclusion can also be applied to other types of non-circular gear.