Direct Drive Misalignment

Figure 1 - Perfect Alignment

Figure 2 - Pure Angular Misalignment

Figure 3 - Pure Offset Misalignment
Misalignment - The most common vibration problem. Unlike unbalance, does not have a single vibration symptom. As a result, it should always be considered as a possibility. 
  • Definition of Perfect alignment - Shaft centerlines are parallel and intersect.
Types of misalignment:
  • Angular - Shaft centerlines intersect but are not parallel
  • Offset - Shaft centerlines are parallel but do not intersect.
It is extremely unlikely that you will encounter a case of either pure angular or pure offset misalignment - it will always be a combination. That results in the wide variety of vibration symptoms.