Health Monitoring of LAV Planet Gear Bushings Using Vibration Signature Analysis Techniques

This paper illustrates the potential benefits of identifying planet gear bushing failures in military Light Armored Vehicles (LAVs) using vibration signature analysis techniques over conventional thermocouple methods. A pneumatically driven test rig was developed to measure the vibrational response of a lubricated dimpled bushing using accelerometers mounted externally to the bushing housing. Fourier-based signature analysis techniques are employed to track the wear history of the bushing liner material under steady load and steady shaft rotational speed. Vibration data collected from the accelerometers was analyzed by calculating the band power of specific frequency bands. Three separate run-to-failure tests showed a direct linear relationship between band power and bushing wear for frequency bands that may be related to the worn dimpled pattern of the bushing. The data was also shown to be a reasonable predictor of bushing wear within specified confidence bounds. In all cases, vibration signature testing was found to be a more reliable indicator of bushing wear history when compared with conventional temperature measurements.