Predictive Maintenance Technologies Flashcards

In vibration analysis, what does a high amplitude peak at exactly 1× running speed (1X) typically indicate?

Answer: Unbalance

A dominant 1X peak in the vibration spectrum is the classic signature of mechanical unbalance in rotating equipment.

Which FFT window function is best suited for detecting closely spaced frequency components with similar amplitudes?

Answer: Hanning

The Hanning window provides good frequency resolution and reduces spectral leakage, making it ideal for detecting closely spaced peaks.

A vibration spectrum shows peaks at 0.5X, 1X, and 1.5X running speed. This pattern is most consistent with:

Answer: Fluid-film bearing instability (oil whirl)

Sub-synchronous peaks near 0.5X are the hallmark of oil whirl instability in fluid-film bearings.

When using an accelerometer for high-frequency vibration measurement, what mounting method provides the widest usable frequency range?

Answer: Stud mount

Stud mounting provides the most rigid coupling, extending the usable frequency range up to the sensor's full specification.

The kurtosis value of a vibration signal is most useful for:

Answer: Detecting early-stage bearing defects

Kurtosis measures impulsiveness in a signal; a rising kurtosis value (above ~4) indicates early-stage bearing defects before they appear in the spectrum.

In rolling element bearing analysis, the Ball Pass Frequency Outer race (BPFO) is calculated using:

Answer: Number of balls, ball diameter, pitch diameter, and shaft speed

BPFO = (N/2) × (1 − Bd/Pd × cos θ) × RPM/60, requiring the number of balls, ball diameter, pitch diameter, and contact angle.

When performing route-based vibration data collection, measurements should ideally be taken:

Answer: Under consistent load and speed conditions

Consistent operating conditions (load and speed) are essential for valid trend comparisons between data collection routes.