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Non-Contact Seals for Hydrostatic Spindle


Sep 1, 2017
Hello. I am looking for information on how to seal hydrostatic spindles. There doesn't seem to be a lot of specific information on this aside from reading patents. The spindles seem to use some combination of non-contact labyrinth seal, porous media aerostatic seal, or air pressure to keep the hydraulic bearing fluid from leaking. If I had to guess how this works...say you have a labyrinth seal and then provide pressurized air into the labyrinth, the air having more psi than the bearing fluid? I have plenty of documentation on hydrostatic bearings but they don't address how to keep the oil from spraying out obviously.
If anyone has worked on this type of spindle before and can help me gain insight, I would be grateful. Additionally, if anyone knows of a supplier or manufacturer who sells "off the shelf" seals for hydrostatic spindle applications that would save me a lot of effort in designing my own.
Thank you for reading.
There is a oil collection channel between the load bearing surface and the end of the bearing housing. The oil drains through the channel rather than through the small radial clearance at the end of the bearing. The oil would need to be under pressure to squeeze through the radial clearance.

If you are concerned about coolant entering the bearing drain channel use one of these:

The viton seal on this assembly does not contact the spindle when air pressure is applied.
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Most hydrostatic spindles dont use seals to keep the oil in. There is typically a labyrinth system, and sometimes a physical seal, but these are primarily for keeping contamination out, not oil in. The oil doesnt leave the spindle because its designed to drain down and be reused.