Lepelletier gearbox

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The Lepelletier gearbox is a further development of the Ravigneaux gear set for use in automatic transmissions . While the Ravigneaux set allows a shift of up to 4 gears, the Lepelletier set enables five or more gears to be achieved.

The Lepelletier set is created by adding another simple planetary set (blue / orange) to a Ravigneaux set (gray / red / green in the picture) and connecting it with clutches. The gear indicator table in the illustration shows that three clutches and three brakes are required to shift seven forward gears and one reverse gear. The ring gear (blue) of the simple planetary gear set is also permanently connected to the motor drive shaft (white). This means that the simple planetary gear set is always rotated even when idling. The output always takes place via the ring gear (gray) of the Ravigneaux set and is connected to the drive wheels via the differential. With a six-speed automatic transmission, the light blue sun gear is permanently blocked, so that the switchable brake for this wheel can be omitted and the fifth gear with the ratio one is omitted. In the illustration, contrary to practice, the Ravigneaux set is shown mirrored vertically for a clearer representation.

literature

  • Konrad Reif (Hrsg.): Conventional drive train and hybrid drives, 1st edition 2010, p. 190f ( preview at google books )

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