Looking for some assistance on a high speed gearbox vibration problem. I have a attached several files of and the one labeled vibration history will give a overview along with some data. The gearbox amplitude reached .72 ins and 159G's peak to peak. The frequency appears to be a multiple of TS but does not line up to anything, and the dominate frequency changes from month to month. From 3414hz, 3596hz, 3775hz, 4133hz, 4495hz,. Fault Frequencies are below.
Motor trend is stable and low, compressor trend follows the gearbox trend, but is much lower, and both are in the attached document.
The gearbox is old and only has one proximity, which is on the high speed output shaft and the reading is always low, and has never been above 2mil
Input 29.8 hz , 4jaw coupling 119.2 hz, lube gear 417 hz
Output 179.8 hz, High Speed coupling teeth 7903 hz, thrust pad 1437 hz
Gearmesh 6466 hz
- Important numbers Gear has 217 teeth, pinion has 36 teeth, high speed coupling has 44 teeth, high speed thrust bearing has 8 pads per active and 8 pad per inactive, lube oil pump has 14 drive and 14 driven teeth,4 jaw love joy coupling all radial bearings are plain babbit and not tilt pad. Compressor vanes are unknown, but looking at the pictures, it appears there are around 17. Compressor has tilt pad bearings with 4 pads each and 8 pads per side of the thrust bearing.