Planetary transmission

The invention relates to a planetary transmission and a power assembly. The planetary transmission comprises a first friction disk, a second friction disk, and a transmission ratio adjusting device, wherein the first friction disk is mounted on a planetary carrier, the second friction disk is located between the first friction disk and a shell, and the transmission ratio adjusting device for actuating the second friction disk to be pressed against the first friction disk or the shell so as to automatically adjust the gear ratio of the planetary transmission. According to the planetary transmission, the change of the gear ratio of the planetary transmission can be automatically, smoothly and reliably realized through a simple and small-occupied-space mechanism. 本发明涉及种行星齿轮变速器和动力总成。所述行星齿轮变速器包括安装到行星架上的第摩擦盘、位于第摩擦盘与壳体之间的第二摩擦盘、以及用于致动第二摩擦盘压靠第摩擦盘或壳体以便自动地调节行星齿轮变速器的变速比的传动比调节装置。根据本发明，可以简单并且占用空间小的机构自动、平滑并且可靠地实现行星齿轮变速器的变速比的改变。