| 摘要 |
The invention relates to a process for sealing off one machine part, rotating relative to another and projecting from this, by means of a shaft-sealing ring connected firmly to the rotating machine part and having axial or radial elastic sealing lips of known design, so that, at a standstill or in the event of slow relative movements, hermetic contact sealing is provided, and in which, at an increasing relative speed, the sealing lip is relieved in a predeterminable manner controllable from outside, lifts off from the sealing face and changes into a contactless shaft seal. According to the invention, compressed air is blown in between the shaft-sealing ring and the sealing face via a ring of nozzle bores and a pressure cushion is thereby generated. Advantageously, the compressed air assisting the lift-off of the seal is cut in only in the starting phase or at low speeds. The invention relates, furthermore, to an apparatus for carrying out this method.
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