Gear Mesh Excitation Spectra for Arbitrary Tooth Spacing Errors, Load and Design Contact Ratio

Abstract

The tendency for gear pairs to exhibit vibration, noise and dynamic tooth loads is influenced by tooth spacing errors, load, design contact ratio and profile modifications. This paper describes an analytical method for assessing the influence of these factors on the excitation force at the gear mesh for gears with a form of profile modification which gives zero excitation at design load in the absence of spacing errors. Amplitude modulation characteristics of the excitation spectrum are of interest since this effect often results from gear manufacturing processes. Tooth spacing errors tend to spread the gear mesh excitation energy over a band. Excitation orders inherent in the gear pair without spacing errors are reduced in amplitude, and the excitation energy shows up in closely adjacent side bands if the errors are a low order nature. Random type spacing errors tend to spread the excitation energy over a broad band while reducing the inherent components except near design load. This would tend to attenuate gear noise and dynamic tooth loads associated with resonant conditions of a gear system.