Gear Problems: Gear Wear (Tooth Wear)

Figure 1 - Typical FFT Showing Wear On Gear Teeth

Gear Wear - Causes high amplitudes at GMF and harmonics. Also, the rubbing / wearing action excites the natural frequency of the gear(s). This can cause unexplained frequencies to appear - they may be the resonant frequencies of the gear(s). The two key indicators are the appearance of the gear's resonant frequency w/ sidebands and the size and number of sidebands surrounding 1, 2 and/or 3x GMF - not the amplitudes at GMF and harmonics alone (these are better indicators for load and alignment).

Gear Wear Symptoms: Higher amplitudes at 1, 2 and/or 3x GMF. High amplitude sidebands around 1, 2 and/or 3x GMF at 1x rpm of the worn gear. Amplitude peak at resonant frequency of the gear(s). Sidebands at 1x rpm of the worn gear surrounding the resonant frequency. Recommended Actions: Inspect gears for wear patterns and check for proper mesh depth (similar symptoms - see previous page). Inspect gears for proper backlash.