Analysis of the performance of the shifting elements in at

A general evaluation system to analyze the performance of clutches in automatic transmission during the earlier phase of designing a gearbox is built up for the engineers who are nonprofessional to the internal characteristics of clutches. A simple theoretical model is deduced to calculate the power loss and the energy loss when engaging a clutch. Based on this model, the influence of the characteristic torque and its rising time on the loss power and energy during the courses of engaging a clutch is also discussed and some useful conclusions have been drawn. Finally, this evaluation system and the new theoretical model are identified with a real automatic transmission in which one clutch is overheated. The calculated result shows that this work can predict its failure successfully.