A Method for Selecting Parallel-Connected, Planetary Gear Train Arrangements for Automotive Automatic Transmissions

A new design method for automatic transmission layout is introduced. This method is based on the lever analogy for planetary gear sets. It uses the desired number of ratios and their magnitudes to size and proportion the generalized lever. The lever is then reduced, yielding the specific gear train and the gear set ratios. This systematic approach eliminates most of the iterations and “dead ends” typical of the design process, since the requirements of the application are used to drive the design.