| 摘要 |
A hollow-type strain wave gearing unit has a cup-shaped flexible externally-toothed gear, in which one shaft end portion of a hollow rotation shaft of a wave generator is located. The shaft end portion is supported by a bearing mounted on a bearing holder fixed to a boss of the flexible externally-toothed gear. The bearing holder has a retainer holding portion to prevent a retainer of a wave generator bearing from coming off in the axis line direction. There is no need to dispose a retainer holding plate of the wave generator bearing inside the flexible externally-toothed gear, whereby the axial length of the hollow-type strain wave gearing unit can be reduced. |
