NCCER Millwright Practice Exam

What is an indication of excessive vibration in machinery?

1. Noise fluctuations

2. Heat generation

3. Indicator sag

4. Oil leakage

The correct answer is: Indicator sag

An indicator sag is commonly associated with excessive vibration in machinery because it reflects changes in the alignment and balance of rotating components. When a machine vibrates excessively, it can cause misalignment and the wear of components, leading to sagging on the indicators that monitor these factors. This sagging suggests that the machinery is not operating correctly and may be at risk of failure if not addressed. The other options, while they can be related to machinery issues, are not specific indicators of excessive vibration. Noise fluctuations might indicate mechanical issues but can also stem from other sources. Heat generation could suggest friction or other operational inefficiencies, and oil leakage might indicate a seal or bearing problem. However, none of these provide the direct connection to the mechanical balance and precision that an indicator sag does.