This information is part of the Modelica Standard Library maintained by the Modelica Association.

This model shows how an automatic gear shift is built up from a planetary gear, a brake and a clutch.

• In the beginning, the clutch is free and the brake fixes the ring of the planetary. Thus we obtain a gearRatio = 1/(1 + planetary.ratio).
• At time = 2 s, the brake frees the ring of the planetary, whereas the clutch blocks the ring and the sun. Thus we obtain a gearRatio = 1.