Abstract: The many stage helical gear train system optimal design which takes the dynamic properties as an objective function is presented. The dynamical model, moving equations and the mathematics model of dynamic properties optimal design are discussed. Because in the dynamical model of system, the intertia, time-variable mesh stiffness, error, damping of the many pair gear & the inertia and stiffness of the shafts are considered. So that, found moving equations are many freedom time-variable charateristic, sloving the time-variable nonliner characteristic equations, we use the method to combine the model analysis with the state analysis. On the base, the mathmatics model of dynamic properties optimal design of gear train system is found. Calculating example shoves that the dynamic properties of the gear train is advantage.

Key words: Dynamic properties, Gear, Optimal design, Train system