Planetary transmission with releaseable one way clutch

摘要

A planetary transmission has a plurality of axially arranged planetary gear units each including sun gears, planet gears in mesh with the sun gears, and ring gears coaxial with the sun gears and in mesh with the planet gears, the arrangement being such that one of the ring gears in each planetary gear unit is blocked from being rotated while the other ring gear is made rotatable for allowing an output to be taken out, upon which the ring gear of which rotation is blocked is made selectable for changing over the reduction ratio, and a smooth bilateral change-over of speed change can be realized by executing the change-over between rotation-blocked and rotation-free states of the ring gear by means of a one-way clutch capable of releasing the rotation blocking.