For horizontal alignment using cross-dial reverse reading, which positions are critical for readings?

• A. 1 o'clock and 11 o'clock
• B. 3 o'clock and 9 o'clock
• C. 12 o'clock and 6 o'clock
• D. 5 o'clock and 7 o'clock

Answer: (B)

In the context of horizontal alignment using cross-dial reverse reading, the critical positions for taking measurements are at 3 o'clock and 9 o'clock. At these points, the dial indicators are set to read the horizontal alignment of the shafts or components being aligned. Positioning the dials in this manner allows for accurate readings of any misalignment, from both the left and right sides of the system, ensuring that any corrective adjustments can be made effectively.

The 3 o'clock position measures the right side of the coupling, while the 9 o'clock position measures the left side. This cross-measurement technique helps in identifying any angular or parallel misalignment, which is crucial for proper equipment operation and longevity. The data collected at these positions can then be analyzed to determine what adjustments are necessary to achieve proper alignment.