CMRT Predictive Maintenance Techniques 2

Question 1

In vibration analysis, a dominant 1× running speed (1X) frequency component most commonly indicates which condition?

Accepted Answer

Mass imbalance

Answer

Bearing inner race defect

Answer

Gear mesh problem

Answer

Cavitation

Question 2

The Ball Pass Frequency Outer Race (BPFO) bearing defect frequency is determined by which set of parameters?

Accepted Answer

Number of rolling elements, shaft speed, and contact angle

Answer

Shaft speed and bearing radial clearance

Answer

Shaft speed and outer race diameter only

Answer

Rolling element diameter and cage frequency

Question 3

When performing vibration analysis, which measurement parameter is generally most sensitive to high-frequency bearing defect impacts?

Accepted Answer

Acceleration

Answer

Displacement

Answer

Velocity

Answer

Jerk

Question 4

A 'waterfall plot' (cascade plot) in vibration analysis is used primarily to:

Accepted Answer

Show frequency spectra stacked over time or speed to reveal trends

Answer

Display vibration amplitude versus time at a single frequency

Answer

Compare two sensors mounted on opposite bearing housings

Answer

Identify phase relationships between vibration signals

Question 5

Resonance in a mechanical structure is most likely to occur when:

Accepted Answer

A forcing frequency coincides with the structure's natural frequency

Answer

Operating speed exceeds the critical speed by more than 20%

Answer

Bearing clearance exceeds manufacturer tolerances

Answer

Lubricant viscosity drops below the recommended range

Question 6

In a Fast Fourier Transform (FFT) vibration spectrum, sidebands spaced at exactly 1× shaft speed around a gear mesh frequency typically indicate:

Accepted Answer

Gear eccentricity or pitch-line runout modulating the mesh signal

Answer

Gear tooth wear uniformly distributed around the gear

Answer

Bearing outer race defect on the gear shaft

Answer

Resonance of the gear housing

Question 7

Which vibration measurement transducer type is most appropriate for measuring absolute shaft displacement in sleeve (journal) bearing machines?

Accepted Answer

Eddy-current proximity probe

Answer

Piezoelectric accelerometer

Answer

Velocity geophone

Answer

MEMS accelerometer