Which of the following can be performed with an accelerometer or mechanics stethoscope and then used to identify faults, aiding in the prediction and prevention of failures in rotating machinery?

• A. Vibration analysis
• B. Thermal imaging
• C. Lubricant analysis
• D. Oil sampling

Answer: (A)

The main idea is using vibration data to condition-monitor rotating machinery and spot faults before they lead to failure. An accelerometer records how the machine vibrates over time, while a mechanics stethoscope helps listen for unusual mechanical sounds. By analyzing the vibration signal in both the time domain and the frequency domain, you can identify patterns that point to specific problems. For example, a strong vibration at the shaft speed (1x) often signals imbalance or misalignment; vibrations at harmonics like 2x can also indicate misalignment or coupling issues; and vibrations at characteristic bearing frequencies reveal bearing faults. Envelope analysis can reveal intermittent impacts from damaged bearings, cracks, or gear tooth issues. Tracking these signatures over time lets you predict degradation and schedule maintenance before a failure occurs. Thermal imaging, lubricant analysis, and oil sampling involve different techniques and equipment, so they’re not the results you’d typically obtain directly from vibration measurements, even though they’re useful in a broader maintenance program.