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An automotive transmission maintains a proper equilibrium between the power and torque produced by an engine and those demanded by the drive wheels. Most automatic, transmissions employ some kind of epicyclic gear mechanisms to achieve the above purpose. The first step in the design process of such a mechanism involves finding a configuration that provides a set of desired speed ratios, and meets other dynamic, and kinematic requirements. In this work, the kinematic structural characteristics of epicyclic gear mechanisms have been identified, and a methodology is formulated to systematically enumerate all possible configurations of such mechanisms. This is achieved by defining a canonical graph to represent the mechanisms. Graphs of mechanisms with up to ten links have been generated using this methodology.

In recent times, the emphasis on increased vehicle fuel economy has spurred considerable interest in the development of variable-valve-timing (VVT) mechanisms for internal-combustion engines. This investigation focuses on the determination of the kinematic structure and the creative design of VVT mechanisms. Following a review of some representative existing VVT mechanisms, several potentially useful, proposed VVT configurations are described; one of these is proportioned and analyzed in some detail.