TEPiciclo - A Software to Help the Planetary Gear Trains Design

In this paper a review about epicyclic gear trains (EGTs) or planetary gear trains (PGTs) is initially presented. These gear trains are transmission systems of high kinematic complexity and difficult visualization. However, their advantages are many: they are compact, light, allow high speed reductions, possess high reliability because they have constant engagement, possess bifurcating capacity and power addition, and allow multiple transmission ratio. One of their main applications is the automatic transmission or power trains of passenger cars and other modern vehicles e.g. trucks, buses, etc. Then, some classic automatic transmission boxes e.g. Simpson, GM Hydra Matic 440 PGT, Ravigneaux, etc. and the TEPiciclo software are shown. This software was created to help in design development for automatic transmission of light vehicles with two simple PGTs linked. It assists the designer in the selection of assembly, positioning and teeth number of gears providing the possible transmission ratio and the torque flow in the selected system. In 2000 the ZF Group started producing the “world's first” 6-speed automatic transmission (ZF 6PH26) for passenger cars. It uses a Ravigneaux and a simple PGT linked. The versatility of TEPiciclo software was shown when searching an alternative gear box able to produce gear ratios close to ZF 6HP26's ones.