Early indication allowed scheduled maintenance – Outer race fault in gearbox

The PROGNOST®-Predictor system showed first increasing Confidence Factor values on the HFE spectrum for the Bearing Bottom Torsion Shaft on August 07th in 2016. Within the following months the confidence still kept on a high level till the beginning of November, when the amplitudes shows the first higher peaks. On November 5th, the amplitudes violated all thresholds and the acceleration rises from 0.1 m/sec² to 2 m/sec². After final maintenance work at the end of November the amplitude and Confidence Factor values went back to normal level. Finally, you see on the last analysis picture the early recognition of HFE 10-20 kHz in relation to the HFE 5-10 kHz and the acceleration spectra.

Analysis view of changing HFE trend

Findings and Learnings

  • Slow increasing indications
    • First confidence in HFE
    • Than amplitudes in HFE
    • Later on confidence in acceleration spectrum
  • Different probes confirmed the issue
  • Decisions to stop was done in cooperation with the customer, the OEM and PROGNOST Systems

“At the past we had some big incidents with this gearbox because it was very difficult to analyze the vibrations with spot measurements. The PROGNOST® system has proven itself as a very reliable monitoring system!!
Also the open communication with the PROGNOST team and Coperion was a big plus in this case.
This way, I want to let you know that we appreciate the open communication, involvement and quick response from PROGNOST ….!”