The Ravigneaux gearset is a double planetary gear set, invented by Pol Ravigneaux, who filed a patent application on July 28, 1949, in Neuilly-sur-Seine France.[1] This planetary gear set, commonly used in automatic transmissions, is constructed from two gear pairs, ring–planet and planet–planet. The gearset provides four forward gear ratios and reverse by braking or restraining various elements of the mechanism.
The Ravigneaux set has two sun gears, a large sun and a small sun, and a single planet carrier, holding two sets of planetary gears, inner planets and outer planets.[2][3] The carrier is one sub-assembly but has two radii to couple with the inner and outer planets, respectively. The two sets of planet gears rotate independently of the carrier but co-rotate with a fixed gear ratio with respect to each other. The inner planets couple with the small sun gear and co-rotate at a fixed gear ratio with respect to it. The outer planets couple with the large sun gear and co-rotates with a fixed gear ratio with respect to it. Finally, the ring gear also couples and co-rotates with the outer planets in a fixed gear ratio with respect to them.
- ^ US patent 2631476, Ravigneaux, "Epicyclic Change-Speed Gear", issued 1953-03-17
- ^ Jim Smart (March 2012). "Understand Automatic Transmissions". Mustang Monthly. Source Interlink Media. Retrieved 2012-11-19.
- ^ Pfeiffer, Friedrich (2008). Mechanical system dynamics. Vol. 13. Berlin: Springer. p. 221. ISBN 9783540794356.