Radial Phase Analysis Across Two Adjacent Bearings

Up to now, we have only analyzed radial phase readings taken on a single bearing at different angular locations. What about comparing adjacent bearings ? Phase is still used as a "relative" reading. When comparing phase angles between bearings, you compare phase angles with the transducer mounted in the same angular location (vertical to vertical, horizontal to horizontal, etc.). Analysis will reveal how the bearings are moving relative to one another at the frequency being measured.

Bearings "In-Phase"

In the animation here, the yellow balls represent heavy spots on the rotor. Since they are located at similar angular locations, the forces generated will cause the bearings to move together, or "in-phase".  If a transducer were mounted vertically on either of the two bearings, the strobe would flash as the heavy spot passes the 12:00 position since the peak signal arrives at that moment.  Our mark (the red key  on shaft) is in the same position (i.e. same phase angle) regardless of which bearing the transducer is mounted on. The bearings are in-phase.