What tool is used to check bearings on an electric motor?

• A. Tachometer
• B. Stethoscope
• C. Vibration meter
• D. Oscilloscope

Answer: (C)

Measuring vibration is the way to assess bearing health in rotating equipment. When bearings wear or lubrication fails, the rotor experiences more roughness and imbalance, which shows up as higher vibration and distinctive patterns at specific fault frequencies. A vibration meter directly quantifies this vibration (and often analyzes its frequency content), making it the most effective tool for identifying bearing issues.

A tachometer only tells you how fast the motor is turning, not whether the bearings are in good condition. A stethoscope can help you listen for unusual noises, but it’s qualitative and less reliable for diagnosing bearing wear. An oscilloscope can display electrical signals or waveform data if paired with sensors, but it isn’t the standard instrument for directly evaluating bearing health.