  The dynamic behaviour of a gearbox fitted out with a helical gear pair is
studied. Shafts, bearings and housing are discretised using the finite element
method. The elastic coupling between the toothed wheels is characterised by a
12x12 stiffness matrix. The calculation of the vibration response induced by
the static transmission error shows that the highest dynamic mesh forces
correspond to a resonant excitation of modes which have a high mesh stiffness
energy. The numerical simulations show that a realistic prediction of the
critical rotational speeds should take account of all the components of the
gearbox.
