The FEM model of three-ring gear reducer is built based on the established 3D assembly model.The dynamic characteristic analysis is carried out by using the Lanczos method.The actual restrictions and contact areas of key parts is reasonable simplif ication in model construct.The problem of key component is processed.Through the dynamic analysis

the natural frequency and vibration are obtained

the bend

torsion and coupling vibration characteristics of the ring plate component are showed.The result indicates that the system has dense modal

wide frequency rang and complex vibration modes.Key words Three-ring gear reducer Mode analysis Ring plates component