Gear noise is caused, to a great extent, by the dynamic phenomena in tooth meshing. It can be characterized by transmission error, which is the root cause for vibration generation and for noise excitation. Transmission error is the most important factor in the generation of gear noise. It can be dened in the following way: Imagine that the input gear is being driven at an absolutely steady angular velocity. It is hoped that the output gear is rotating at a steady angular velocity. Any variation from this steady velocity gives a variation from the “correct position” of the output, and this is the transmission error, which will subsequently generate vibration and noise excitation. More formally:
Transmission error is the difference between the angular position that the output shaft of a drive would occupy if the drive were perfect and the actual position of the output.