A Non Linear Model of the Geartrain of the Timing System of the Ducati Racing Motorbike.

This work deals with the elastodynamic model of the geartrain operating the desmodromic valve trains of a fourcylinder ‘L’ engine of the Ducati racing motorbikes. The geartrain dynamic behaviour is simulated by means of a lumped parameter model which takes into account the mass moment of inertia of gears and shafts, the torsional shaft compliance, the damping effect, the parametric excitation due to the time-varying meshing stiffness, and the presence of backlash between meshing teeth. In particular, the possibility of tooth contact on both contact lines is included in the model. The comparison between numerical results and experimental measurements shows that the effectiveness of the model is satisfactorily assessed. The model allows the prediction and interpretation of the actual dynamic behaviour of the system, so to be used in design optimisation of the geartrain.