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High axial vibration in uncoupled motor

High axial vibration in uncoupled motor

(OP)
I have a series of water pumps that are generating elevated 1X in both axial and radial directions. I have completed alignment adjustments on them all and the values have decreased marginally. In an attempt to solve the issue i have uncoupled the motors and run again. The motors are showing 1X at about 120% of radial. Bearing condition indications are good - no damage as yet.
Now these are chunky Russian made motors. The fan is steel and integrated inside the NDE bearing (between the bearing and the rotor) so i cannot remove it to check for unbalance. What are my options here? My thougths now are to complete a phase survey of the motor to determine what is going on (the pumps are 30km away on the worlds worst road so this is not a simple task)
What are the possible reasons for high axial in an uncoupled motor? I can only think of a cocked fan or bearing - phase to determine where to look. Anyone point me in another direction?

Thx

RE: High axial vibration in uncoupled motor

Phase measurements may shed some light on the issue(s).

Resonance? Can you perform a bump test to determine if the motors are resonant in the axial or radial directions?

Balance? Sometimes unbalance will result in axial vibration (usually related to over-hung rotors). Balancing the rotor can drive down both the radial and axial vibration amplitudes.

RE: High axial vibration in uncoupled motor

Vertical or horizontal motor? (I'm guessing horizontal, but ... )
Are the axial measurements made on a flimsy cover? (I'm guessing not, since you said there is a cooling fan inboard of the NDE bearing, but .... )
Horsepower, bearing type, etc, etc, etc.

Pictures of the motor and installation would be a BIG help.
As would history.

I'd be interested in a survey of the axial vibration ( 1X amplitude and 1X phase ) all over the motor end bell and including the motor feet.
Similar to the attached image.

While I was there I'd do something similar for the vertical and horizontal vibration at both ends of the motor as well.

The V and H vibration measurements should also extend from the bearing/shaft centerline across the motor, to the motor feet and anchor bolts and beyond to the pump base, sole plate, and foundation.

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