Previsione del comportamento dinamico delle ruote dentate Gear dynamics force and displacement forecast As a very key part in automobile powertrain system, transmission’s durability,stability, and NVH performance all have critical significance for vehicle’s quality and performance. When the transmission is running, all of its transfer parts and support parts are suffering huge loads, which will make the transfer parts deform and deviate from the original position even be damaged. Meanwhile, manufacturing defects of parts and error of assembly also will influence the working precision and quality of the transmission. Therefore, analyzing and optimizing the loading status is an effective way to improve transmission’s quality and performance.