Staff Answer
Oct 12, 2026 - 06:10 AM
When checking the oil level in a Nidec U.S. Motors Vertical Hollow Shaft (VHS) electric motor, the motor must be at rest (off).
According to the official U.S. Motors Lubrication Guide, the unit must be at a complete standstill, and the electrical controls should be locked open (LOTO) to prevent accidental energizing while servicing.
Correct Procedure for an Accurate Reading
- Check it while stopped and settled: The oil must be given a few minutes to settle fully back into the reservoir so that you get an accurate representation of the oil volume.
- Target Levels: When the motor is off, the oil level visible in the sight gauge window should sit between the "MIN" and "MAX" marks.
Why you shouldn't check it while running:
Checking it while running will give you a false low reading. When a vertical machine operates, a significant volume of the oil leaves the main sump to lubricate and cool the upper thrust bearings. Furthermore, moving parts will cause turbulence in the oil reservoir, making the sight glass level highly unstable and unreliable
