What will be seen in the spectrum if an overhung machine is out of balance?

When an overhung machine is out of balance, the most notable indication in the spectrum will be a high peak at 1x in the vertical, horizontal, and axial directions. This phenomenon occurs due to the imbalance causing the system to vibrate at the rotational frequency of the machine, which is represented as 1x in vibration analysis.

In an overhung arrangement, the center of mass is not aligned with the axis of rotation, leading to a centrifugal force during rotation. This force generates vibrations primarily at the fundamental frequency of rotation (1x) in multiple directions where the machine is supported or operates. Thus, significant peaks will be visible in the spectrum, reflecting the imbalance's impact.

The presence of high peaks at 1x in all directions showcases the direct relationship between the rotational speed and the imbalance. It also signifies that the machine’s vibration is primarily due to the imbalance rather than other causes.