Couplings

Couplings exist in many types and configurations, and defects in them usually cause symptoms similar to misalignment. Frequently coupling problems will produce stronger 1X vibration components than simple misalignment does. If the coupling is not true, i.e., has non-parallel flange faces, a vibration similar to angular misalignment is produced.

Coupling imbalance is also a common problem, and results in high 1X and 2X radial and tangential components.

Coupling wear can produce all the symptoms of misalignment and looseness. Three-jaw motor couplings that contain spacers of improper length will cause strong axial and radial components at 3 times shaft RPM.