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Misalignment occurs when the driver’s (motor) shaft centerline of rotation is not concentric with the driven shaft’s (pump) centerline of rotation. Even today some professionals assume that the coupling will deal with the misalignment. However, the misalignment tolerance built into the couplings merely show how much misalignment the coupling can handle and still transfer power. They are not designed to magically make machine misalignment disappear. The shaft misalignment will transmit critical loads and forces along the shafts creating high vibration and premature wear on both the driver and driven machine.  Misalignment happens in both the vertical and horizontal planes and is identified as:

  • Offset: The distance between the two shafts’ centerlines at any point along their centerlines, also known as parallel misalignment.
  • Angularity: The angle or rate of change of the offset between the two shafts’ centerlines, also known as gap difference over the coupling diameter, or Rise/Run.

Watch our Shaft Alignment Know-How video to learn about the concepts of Offset & Angularity as they relate to aligning rotating equipment

To ensure your machines run reliably, misalignment needs be checked and corrected to the tolerances provided by the facility or machinery manufacturer.

Watch our Shaft Alignment Know-How video to learn the causes and effects of having misalignment in your rotating equipment

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by Carlos Bienes CRL