High-Speed Gear Vibration And Noise Experience

Abstract

High-speed gear pinion precession-shuttling and noise, caused by overhanging weight of the coupling and by misalignment forces generated by tooth friction in the coupling, are being controlled by reduced bearing clearances. A statistical analysis of high-speed gear, mesh-frequency, vibrations was used to decide that sleeve bearings would not control the precession-shuttling adequately and that use of tilting-shoe radial bearings was necessary. Noise data collected to solve the pinion precession-shuttling problem indicate that acoustic passages in the gearbox may be excited by windage at frequencies not related to vibration multiples of mechanical running speed or gear mesh-frequency. Measured resonant frequencies of structural sections of the gear-box when matched to measured acoustic frequencies or mechanical vibration frequencies also appear to cause unnecessary noise. These experiences suggest that some relatively minor design changes, by gear manufacturer-customer agreement, could reduce the chance of mechanical malfunction by installation of tilting-shoe bearings and could eliminate noise sources in preference to use of noise abating gear-box covers.