The importance of shaft alignment .The most frequently asked questions by managers, engineers, foremen, contractors, and trades people concerning the subject of shaft (mis)alignment and its importance in maintaining industrial rotating machinery are discussed. What exactly is shaft alignment? In very broad terms, shaft misalignment occurs when the centerlines of rotation of two (or more) machinery shafts are not in line with each other. As simple as that may sound there still exists a considerable amount of confusion to people who are just beginning to study this subject when trying to precisely define the amount of misalignment that may exist between.