How can you check for parallel alignment using a dial indicator?

• A. By measuring the distance between shafts
• B. By observing the machine's vibration
• C. By rotating one shaft and measuring the other's distance
• D. By using visual inspection only

Answer: (C)

Checking for parallel alignment using a dial indicator involves measuring the relative displacement between two shafts as one is rotated. This method provides precise measurements of misalignment, allowing for an effective assessment of alignment conditions.

When you rotate one shaft, the dial indicator attached to the other shaft detects any variations in distance. If both shafts are perfectly parallel, the reading on the dial indicator will show consistent values across the rotation. Discrepancies in the dial indicator readings will indicate that there is a misalignment which requires correction.

This method is favored because it offers a quantitative way to assess alignment, making it more reliable than purely visual inspections or measuring distances without a sensitive instrument like the dial indicator. Visual inspections alone may miss subtle misalignments that could lead to equipment failures over time. Similarly, measuring the distance between shafts does not account for the dynamic nature of the shafts' movement, while observing machine vibration focuses more on operational performance rather than precise alignment measurements.