One of our Gardner Denver Air compresser is showing an upward vibation trend after installation on seven month back.There is a previously this was failed due to comp. thrust bearing damage.That time the peakvue and axial readings are very high( 0.4 IPS and 9.3g), this time those readings looks normal except slightly high peak vue on Comp DE bearing ( during installation 0.6g and now 2.0g).The main frequency on picture is 4.47X and its harmonics. No idea were it is from. This is directly driven by a 50 HP 1785RPM motor.Not sure there is any gears inside. The photo of comp is also attached.

Spectra.doc (676 Kb, 33 downloads) Spectra

Shameer,

Its hard see from the photo, but the non-driven rotor in the background appears to be smaller diameter than the driven-rotor in foreground. If this is the case and both rotors have 4-lobes, then the non-driven rotor speed is higher (1997 rpm) in proportion to rotor diameters. If this is the case, then fault may be on the non-driven rotor or its bearings. There may be an issue with thrust bearing position or that thrust position changes with load or by thermal expansion/distortion of case and rotor. I don’t think the compressor has timing gears, but it would be wise to verify the rotor geometry from the junk parts.

Walt

quote:

but the non-driven rotor in the background appears to be smaller diameter than the driven-rotor in foreground. If this is the case and both rotors have 4-lobes, then the non-driven rotor speed is higher (1997 rpm)