Function of Planetary Gear Set

The components internally-geared wheel (1) and sun gear (3) of a planetary gear set are alternately driven or braked securely via the actuators multiple-disc clutch and multiple-disc brake. The planet gears (2) can roll on the internal toothing of the internally-geared wheel (1) and on the external toothing of the sun gear (3). in this way varied gear ratio stages and a reversal of rotation are achieved, without having to move gear wheels or shift sleeves. If two components of a planetary gear set are rigidly connected together, the planetary gear set is locked and rotates as a closed unit.

The torque and speed conversion takes place corresponding to the lever ratios or ratio of the numbers of teeth of the driven to the driving gear wheels and is designated as gear ratio i. The overall ratio for several planetary gear sets connected in series is given by multiplication of the part ratios.

Advantages of a planetary gear set:
- Shiftability under load
- Production of several ratios
- Constant mesh toothing
- Simple reversal of direction
- Higher efficiency
- Coaxial position of input and output
- Compact design