<div class="htmlview paragraph">Epicyclic gear trains are important part of automotive transmissions. They are present in automatic transmissions and in differentials of most vehicles. The dynamic behavior of a single epicyclic gear is well known, and this study presents the results obtained based in a model of a complete transmission. Initially the Wilson gearbox is presented. The main principles of the model are described. Following, the results of a simulation using the model are shown. Finally, the influence of the inertias in the model are presented and it is done some discussion about it</div>