Study on load sharing performance of a helicopter transmission system

Abstract In this paper, aiming at a relatively new dual-input, single-rotor output, single-tail-drive output two-branch cylindrical gear combining transmission mechanism, the principle of its load imbalance is analyzed. Considering the system’s installation errors and shaft support deformation, the static mechanics method is adopted to analyze the deformation compatibility relationship, and a calculation model for the LSC (load sharing coefficient) of this system is established. Under the condition of the meshing phase difference that causes the load sharing unevenness difference between the left and right branches, the influences of various factors on the system’s load sharing coefficient are analyzed, including: the change of torsional stiffness affected by the structural parameters of the torsional stiffness of elastic shaft, input torque, the backlash of gear pairs at all stages and the support stiffness affected by bearing structural parameters. This analysis facilitates the optimization of system structural parameters to enhance load sharing characteristics during the design process. The results show that the backlash of gear pairs at all stages has a relatively significant impact on the system’s load sharing performance, followed by torsional stiffness, while the influence of support stiffness is relatively small. Therefore, during the design process, installing splines to appropriately control the backlash can significantly enhance the system’s LSC, while optimizing the structural parameters of the shaft can slightly enhance the system’s load sharing characteristics.