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Misalignment of a Gearbox

The PROGNOST®-Predictor was showing several impacts in the tie waveform of a 24' Raymond gearbox. This was a first indication of a tooth problem on one of the gears. After several other analysis work the failure was localized and later findings inside of the gearbox showed the high accuracy of PROGNOST®-Predictor.

Problem description

  •  24′ Raymond was showing impacts in the time waveform consistent to a tooth problem
  • Also, in velocity spectrum many side bands of ring gear speed around gear mesh indicating problems with this ring gear
  • This separator has had gearing problems 3 times in the last 2 years

Analysis

Time waveform indicating fault

  • Single impacting at once per revolution and then there were other impacts showing multiple tooth problems

Time waveform trend views

  • Major step change indicates first tooth problem
  • Trends over 6 (upper) and 7 (lower) month

Vibration Signature

  • Increasing Time Waveform energy with once per revolution impacting and many gear mesh sideband frequencies of Ring Gear speed

 Findings

  • Misalignment of gearing gearbox
  • Found several broken teeth on ring gear possibly due to age and excessive wear in lower unit causing misalignment

Result

Ring gear failure

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