Total Vibrational Excitation and Transmission Error of Gears as Index of Vibration and Noise of Power Transmissions

Gear vibration is induced by the excitation due to manufacturing/alignment errors and periodical chasnge of meshing tooth stiffness with progress of gear rotation. As an index for evaluating the degree of gear vibration and noise as functions of gear dimensions, accuracy and driving conditions, transmission error of gears and total vibrational excitation are widely accepted. This report clarifies that the influence of transmission error and that of total vibrational excitation on gear vibration are equal in their first order frequency component, and the difference between them is due to the higher order frequency components of the periodical change of meshing tooth stiffness. The difference in the degree of influence of these two indices on the relative rotational vibration of gears is discussed using numerical examples. Propriety between both indices is also discussed to predict the actual gear noise of automotive power transmission of personal cars in production.