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Planetary Gear Set, Basic Function - GF27.50-P-1000A

Model all with transmission 725 

Example illustration of automatic transmission with planetary gear sets 

Fig 1: Planetary Gear Set Components Location - Model All With Transmission 725
G14472105Courtesy of MERCEDES-BENZ USA

Overview 

This document contains information on:

General 

The 4 planetary gear sets (1.1, 1.2, 1.3, 1.4) are located in the mechanical part of the automatic transmission. The planetary gear sets are used for power transmission and the formation different gear ratios.

IMPORTANT A planetary gear set consists of a ring gear (4), the planetary gears (2) mounted in the planet carrier (3), and a sun gear.

Planetary gear set 

G14472106Courtesy of MERCEDES-BENZ USA

Function 

The ring gear (4), sun gear and planet carrier (3) of a planetary gear set are alternately driven or braked via the multiplate clutch and multidisk brake shift elements. In doing so, the planetary gears (2) can roll on the internal toothing of the ring gear (4) and on the external toothing of the sun gear. This allows for a variety of gear ratios and the reversal of the rotation direction without the need for moving gear wheels or sliding sleeves.

Torque conversion and RPM conversion take place in accordance with the lever ratios or the ratio of the number of teeth of the driven to that of the driving gearwheels.

If 2 components of a planetary gear set are rigidly connected to each other, then this is locked and rotates as a closed unit.

Features of a planetary gear set: