A dynamic model with bend-torsion coupling was established for two-input cylindrical gears split-torque transmission system

in which the time-varying mesh stiffness

backlashes

mesh errors and mesh damping of gear pairs were considered. With use of the characteristics of closed loop structure

differential equations could be obtained without rigid displacement

using the relationship between relative meshing displacement and the transmission shaft torsional displacement. Through solving the dynamic equation of system by the fourth-order Runge-Kutta method

the load sharing coefficients of system were acquired. The results show that load sharing coefficient of system is little influenced by torsional stiffness of input shaft. The load sharing coefficient of split and synthesized torque stages is sensitive to torsional stiffness of duplicate gear shaft

and reduction of the torsional stiffness of duplicate gear shaft contributes to the improvement of load sharing performance of system. When torsional stiffness of duplicate gear shaft is less than 1.1×105(N·m)/rad

the load sharing coefficient of system is less than 1.06. Torsional stiffness of output shaft has no significant effect on the load sharing coefficient of split and synthesized torque stages.