When should the lube oil system be secured for taking bearing depth micrometer readings?

The correct choice indicates that the lube oil system should be secured 24 hours prior to taking bearing depth micrometer readings. Securing the lube oil system for this duration allows the oil to fully drain from the bearings, ensuring that all oil is removed before measurements are taken. This is crucial because the presence of oil can affect the accuracy of the measurements.

Measuring bearing depths accurately is important for ensuring proper clearance and alignment within machinery. If oil remains in the bearings during measurement, it can lead to erroneous readings, which could result in improper adjustments and potential mechanical failures. Therefore, the practice of securing the lube oil system well in advance is a critical procedure that supports the integrity and reliability of the measurement process in maintenance activities.