Abstract: Based on the structure of herringbone gears and using the lumped-parameter method， a generalized dynamic model of a herringbone planetary gear train (HPGT) was presented to study the forced vibration characteristics. Taking into account the manufacturing eccentric errors and tooth profile errors， bearing stiffness， time-varying mesh stiffness， and gyroscopic effect， the model can be utilized for the vibration performance analysis with different types of manufacturing errors and arbitrary number of planets. The forced vibrations of an HPGT were numerically computed with the presented model， and analyzed in time and frequency domain， respectively. The effects of manufacturing errors especially the sun gear eccentric error E_s on dynamic characteristics were discussed， revealing that manufacturing error excitations， such as the sun gear eccentric error E_s， enhance the dynamic responses and dynamic mesh force fluctuations in HPGT.

Key words: herringbone planetary gear train(HPGT), manufacturing errors, time-varying mesh stiffness, dynamic modeling, dynamic performance