Based on the theory of concentrated parameter

a dynamics model of the encased differential herringbone train was set up.The elastic deformation of the bearings

the time-varying meshing stiffness

the errors and the intermediate floating component were considered in the model.The helical gear meshing stiffness formula was introduced to calculate the time-varying mesh stiffness of herringbone in parallel way.Through solving of the dynamic equation by Fourier series method

the dynamic load sharing coefficients of the train were acquired and the impact of run-out and meshing-frequency errors on the load sharing was analyzed.The research results show that the load sharing coefficient of the differential stage affects the meshing-frequency errors greatly

it is increased with the meshing-frequency errors and is seldom influenced by the run-out errors.The load sharing coefficient of the encased stage is very sensitive to the run-out errors

it is largened with the run-out errors and is hardly affected by the meshing-frequency errors.The meshing-frequency errors have greater influences on the load sharing coefficient of the differential stage than run-out errors' on that of the encased stage

so the differential stage has a bigger load sharing coefficient than the encased stage.