Journal Bearing End seals

[MechatroPro]

Hello,
I'm wondering how Journal bearings are sealed at the two ends to prevent leakage of the pressurized oil inside the bearing at the start of the rotor operation. because at at that momemnt, oil pressure is supplied by external means and should be more more than the rotor weight to lift the rotor at the start.
I know bearing housing are supplied with labyrinth seals at the end, but that shouldn't be sufficient to seal the pressurized oil at startup.
If anyone can explain, I'd appreciate it.

 

[JJPellin]

Most journal bearings are hyrodynamic. They require the rotation of the shaft to produce the hydraulic force to lift the weight of the rotor. This bearing will normally include end seal to limit the leakage of oil from the ends. These seal are typically a close clearance aluminum laby or a narrow land with a babbetted surface.

You were describing a hydrostatic bearing that has enough hydraulic pressure to lift the rotor without rotation. These are much less common. The pressure is not maintained in the entire bearing. There are relatively small areas of the bearing with cavities where very high pressure oil is injected. This oil could be called jacking oil on a machine that rolls slowly on turning gear, for example.


Johnny Pellin

 

[Tmoose]

Hydrodynamic or hydrostatic, on any pressure fed bearing I'd expect a small cavity with a drain back to the main sump between the bearing and the seals, and a flinger/slinger or some other feature on the shaft to deflect a direct squirt away from the seal gap.

http://www.surplusjeep.com/MB-GPW/Images/Engine longitudinal section.jpg

http://www.buchundbild.de/media/images/org/BuBshopOM366.jpeg