Practical Case Studies On Vibration Analysis Pdf Online

The Asset: 75 HP electric motor driving a conveyor gearbox. Speed: 1780 RPM. Bearings: SKF 6315 (Inner race and outer race). The Complaint: Squealing noise during startup, normalizing after 10 minutes. No temperature alarms. The Data: Acceleration envelope (gE) spectrum revealed a pattern of sidebands around 2.3 kHz. By calculating the bearing defect frequencies using a standard formula sheet (available in most vibration analysis PDF guides), the analyst identified:

"Always perform phase analysis when diagnosing 1x RPM issues. Do not assume unbalance without cross-checking phase readings."

A pump coupled to a diesel engine (variable speed) vibrated violently when hot, but ran smoothly during morning startup. Operators assumed "thermal growth" but didn't know how to measure it. Practical Case Studies On Vibration Analysis Pdf

"Always compare horizontal vs. vertical phase when seeing 1x RPM. Overhung rotors behave differently than rotors between bearings."

Equipment: 300 kW gearbox, input 1450 RPM, output 290 RPM.
Symptom: Intermittent high-frequency “clacking” under load; no change in housing temperature. The Asset: 75 HP electric motor driving a conveyor gearbox

Data Collected:

Diagnosis: Localized tooth crack on input pinion. A pump coupled to a diesel engine (variable

Action Taken:

Result: Avoided catastrophic failure (which would have destroyed housing and downstream rotor).

Key Takeaway: Sidebands around GMF spaced at shaft RPM = modulation due to a fault on one gear (crack, missing tooth, spall).