What preliminary steps should be taken before performing cross-dialing?

• A. Both shafts must be misaligned
• B. Mount dial indicators with plungers depressed halfway
• C. Tighten hold down bolts to maximum torque
• D. Remove any existing shims

Answer: (B)

Mounting dial indicators with plungers depressed halfway is crucial before performing cross-dialing because this setup allows for accurate measurement of shaft alignment. When the plungers are in the correct position, they can better detect any misalignment as the shafts rotate. This ensures that the readouts from the dial indicators reflect true movement and alignment condition, providing reliable data for alignment adjustments.

Prior to cross-dialing, ensuring the dial indicators are mounted with the plungers at the appropriate depth helps prevent false readings that could occur if the indicators are not set correctly. A proper setup in this way supports the effectiveness of the alignment process and leads to improved operational efficiency once the machinery is back in service.

The other steps, while they may be relevant to other aspects of machinery setup, do not specifically relate to the effectiveness of the cross-dialing measurement technique as directly as ensuring the dial indicators are correctly positioned.