Regarding the issue with the top shaft oil
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We have the bearing shells for a large motor; before starting the machine, it is necessary to activate the jacking oil pump to create pressure in the jacking oil. I would like to ask whether there is any difference between these bearing shells and ordinary bearing shells Or is it that the conventional bearing structure simply involves making a small hole at the bottom of the bearing to inject high-pressure oil, thereby lifting the shaft?
Whether a shaft bearing requires a thrust device depends on the starting load of the bearing and the actual load level.
There are many basic structures for bearing shells; from the pictures provided by the poster, it seems to be tilting-type bearings (as well as elliptical bearings and cylindrical bearings, etc.). Rotors that have oil holes at the top generally have a greater mass, which helps to reduce the starting torque during startup； On the other hand, it helps to protect the bearing shells :):):)
The oil used for lifting the shaft is what I call lift oil; its pressure ranges from 10 to 80 MPa. Due to the heavy weight of the rotor, holes are provided right below the shaft bearings. Before starting up, high-pressure oil is used to lift the rotor, thereby reducing the load on the motor used for rotating it. Generally, an interlock system is in place: the rotor can only be rotated once the lift oil pump has started operating