In vibration analysis, what does a 1x peak in the vertical direction and a much stronger 1x peak in the horizontal direction suggest?

A 1x peak in vibration analysis represents the fundamental frequency corresponding to the rotational speed of the machine (known as the running speed frequency). When evaluating the peaks in different directions, such as a strong 1x peak in the horizontal direction and a weaker one in the vertical direction, this typically suggests specific conditions affecting the machine’s performance.

Having a significantly stronger 1x peak in the horizontal direction compared to the vertical generally indicates that there may be an imbalance in the rotor. However, the choice of structural looseness aligns well with the observed vibration characteristics. Structural looseness can lead to a condition where the vibration response in one direction (usually the direction with the least stiffness, which is often horizontal in machines) is amplified relative to the other direction.

In this scenario, the presence of a robust 1x peak horizontally suggests that the machine's structure may not be adequately supported or secured, leading to more pronounced vibrations in that direction. This can occur due to issues such as looseness in mounts or foundation, resulting in increased vibration levels and potentially a weaker response in the vertical direction.

While an imbalance does also produce vibrations, it would typically manifest with significant peaks in both horizontal and vertical directions unless compounded by structural issues. Thus, identifying structural loosen