Load on a journal bearing in a vertical shaft

[sainathadapa]

i have to design a journal bearing for a vertical motor shaft. what loads act on these bearings? since the shaft is axial, are they any loads that act on the bearing. here i am talking about journal/plain bearing, not the thrust bearing which supports the vertical load. what type of failure we have to consider for the case?

 

[256bits]

Even if upright you would still have to do a vibrational analysis. I think it is called critical speed or something like that and make sure you are not operating at that speed for the shaft - best to be either above or below that speed. Reason being is that no shaft can be made perfectly round, or in another sense no shaft will have its axial centre of mass coincide with its geometric centre. Use the extreme tolerances of the shaft to do a calculation. And compare to that with what the journal bearing can tolerate.

Have you thought of how you would lubricate the upright journal?

 

[sainathadapa]

the shaft is for a submersible motor, there is hydrodynamic lubrication for the journal bearings

 

[DickL]

There will be some level of rotor unbalance loads and probably some level of lateral loading resulting from whatever the motor is driving. I'm not certain of this, but I seem to recall motor designers commenting there is usually some level of unbalanced or non-symmetrical magnetic forces acting on a real motor's rotor. Non of these would normally be large, as in the weight of the rotor. During start up and shut down there may also be transient lateral loadings.

I'm not sure of this, but I think standard motors for vertical operation have pretty much the same lateral bearing capability as do standard horizontal operation motors. Of course that is probably due to economic reasons and not knowing what lateral loads may result from its application.