The simple gearset illustrates basic principles, but it can’t obtain all the ratios required.
In practice compound planetary gearsets are used.
The Ravigneaux gearset has two simple gearsets, with only one ring gear.
All gears are always in mesh, just as in a simple gearset.
A primary sun gear meshes with short primary pinions. A secondary sun gear meshes with long secondary pinions.
Both sets of planet pinions are mounted in a common planet carrier and they mesh in pairs. The outer secondary pinions mesh with the ring gear, which is attached to the output shaft.
A Simpson gearset has two simple gearsets, connected by a long sun-gear common to both gear sets.
The sun gear is free to rotate on the output shaft. It is constantly meshed with the planet pinions of both sets. They in turn mesh with their individual ring gears.
Both sets are also connected by each having a part splined to the output shaft - the ring gear of the rear set, and the planet carrier of the front set.
The input shaft is separate from the gearset. The drive is transmitted through one, or more clutches, depending on the gear and range engaged.
Two bands and a one-way clutch are also used to control the gearset components.
