Ask two questions:

Velocity increased from 3.0 mm/s (Zone B) to 9.5 mm/s (Zone C) over 3 weeks. Spectrum: Dominant 1× RPM (600 RPM = 10 Hz) with high 2× and 3× harmonics. Time Waveform: Asymmetric, with a sharp negative spike every revolution. Diagnosis: Looseness in the gearbox output shaft bearing due to a cracked inner race. Action: Replaced bearing. Vibration returned to 2.8 mm/s. Result: Avoided catastrophic shaft shearing.

The practical vibration primer is not about solving differential equations; it is about pattern recognition and disciplined data collection. By understanding the relationship between , a technician can identify 90% of common rotating machinery faults without advanced mathematics. The key takeaways are: (1) Always use velocity for overall trending, (2) Always know your 1× RPM frequency, and (3) Always mount the sensor rigidly.

Most beginners only look at the "Overall Vibration" number (e.g., 0.2 inches per second). The Primer teaches why the Overall number is a lie. It uses simple analogies (like an orchestra playing out of tune) to explain why you must look at the FFT spectrum. The PDF uses side-by-side screenshots showing how two different machines with the same overall level have radically different faults.