摘要 |
A strain wave reduction gear and a variable transmission ratio steering apparatus move a flexible gear and a rigid gear differentially, even if the flexible gear is in a fractured state. According to the strain wave reduction gear, the flexspline mates with the inner side of the elliptical hole of the rigid cam via the flexible bearing; therefore, the flexspline maintains an elliptical shape that is similar to the elliptical hole and maintains the meshed state-even if the flexspline fractures. Therefore, when the rigid cam rotates, the mesh positions of the flexspline and the first and second circular splines can be shifted in a circumferential direction. Namely, even in a state wherein the flexspline is fractured, the first circular spline and the second circular spline can be moved differentially by the difference in their tooth counts.
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