Misalignment
Angular Misalignment is characterised by high axial vibration, 180° Out-of-phase across the coupling. Typically will have high axial vibration with both 1x and 2x rpm. However, not unusual for either 1x, 2x or 3x to dominate. These symptoms may also indicate coupling problems as well. Parallel Misalignment
Offset Misalignment has similar vibration symptoms to Angular, but shows high radial vibration which approaches 180° Out-of-phase across the coupling. 2x often larger than 1x, but its height relative to 1x is often dictated by coupling type and construction. When either Angular or Radial Misalignment becomes sever, it can generate either high amplitude peaks at much higher harmonics (4x - 8x) or even a whole series of high frequency harmonics similar in appearance to mechanical looseness. Coupling construction will often greatly influence the shape of the spectrum when misalignment is severe. Misaligned Bearing Cocked On Shaft
Cocked Bearing will generate considerable axial vibration. Will cause twisting motion with approximately 180° phase shift top to bottom and/or side to side as measured in the axial direction of the same bearing housing. Attempts to align the coupling or balance the rotor will not alleviate the problem. The bearing must be removed and correctly installed.
-::- This site is designed and authored by David Stevens IEng MIET FIDiagE MICML -::- |
