ABSTRACT
This chapter discusses the problems of noise and vibration. The reduction of gear noise/vibration excitation is a complex engineering problem. Gear noise is caused, to a great extent, by the dynamic phenomena in tooth meshing. The three fundamental conditions that gearings have to fulfill are violated in approximate gearings, that is, in parallel-axes, intersected-axes, and crossed-axes gear pairs. In approximate gearings, either the base pitch of a gear, the base pitch of a mating pinion, or both are not equal to the operating base pitch of the gear pair. The base pitch variation is a root cause for vibration generation and excessive noise excitation. Base pitch variation is caused by one of the following factors. They are: the deviation of the gear tooth flank geometry in relation to the desired geometry; the displacement, both linear and angular, of the gear tooth flank in relation to the axis of rotation of the gear/pinion; axis misalignment.
