TL;DR
Vibration is most often a worn bearing. Listen for grinding, log a vibration reading, and plan a bearing replacement during the next planned outage.
What you might see
- rumbling or grinding noise
- elevated vibration at running speed
- warm motor housing
- shaft whip or knock
Likely causes
Worn or pitted bearings, typical after 30,000+ operating hours
Bearing contamination from dirt, moisture, or grease degradation
Bearing electrical fluting from VFD common-mode currents (no shaft grounding ring)
Coupling misalignment driving load into the motor bearings
Required tools
- IR thermometer
- Vibration meter (optional but recommended)
- LOTO kit
- Replacement bearings per Baldor nameplate
Safety first
- Lock out and tag out the motor disconnect before opening the conduit box or rotating the shaft by hand on a coupled load.
- Never reach into a coupling unless the disconnect is locked out and you have verified zero rotation.
Procedure
- 1
Stop the motor and lock out / tag out the upstream disconnect.
- 2
Rotate the shaft by hand and listen for grinding, catching, or roughness in the bearing.[1]
- 3
Measure the motor housing temperature near each bearing with an IR thermometer; readings above 85°C trend toward failure.
- 4
If you have a vibration meter, take a reading at the drive-end and non-drive-end bearing housings. Velocity above 0.4 in/s is a red flag.
- 5
Check the maintenance log for total operating hours. If the motor has more than 30,000 hours and you have any bearing symptom, plan a bearing change at the next outage.[1]
- 6
Order replacement bearings by the part number on the Baldor nameplate. Match shielding and grease grade exactly.
- 7
If vibration is severe (>0.4 in/s) or the motor is making intermittent grinding, schedule the replacement immediately rather than waiting.
Sources
Baldor Reliance Industrial Motor Maintenance Manual, Baldor Electric Company (ABB)
Baldor Industrial Motor Maintenance Manual, bearing inspection and replacement procedures (general)
View source
More guides for Baldor Super-E (EM/EJMM)
How to diagnose intermittent operation on a Baldor Super-E motor
Intermittent stops or restarts almost always come from loose electrical connections or a worn contactor. Check the contactor first, then torque-test the conduit box terminals.
How to fix a Baldor Super-E motor making noise from coupling misalignment
Misalignment between the motor and the driven equipment creates a knocking or rumbling noise. Check soft foot first, then measure parallel and angular alignment with a dial indicator or laser tool.
How to fix overheating and excessive current draw on a Baldor Super-E motor
Overheating with high current is usually mechanical overload or supply phase imbalance. Measure phase currents, check the load, and verify supply voltage balance is within 1%.
How to fix reduced speed on a Baldor Super-E motor running on a VFD
If the motor runs below the commanded speed, check the VFD's frequency reference, slip compensation, and supply voltage. Mechanical load increase can also drag speed down.
Stop fixing the same fault twice.
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