Device in machine elements with closed casing

Claim 1

In a grinding apparatus of the defibrator or refiner type including a closed casing having a pressure therein differing from that of the ambient atmosphere, at least two grinding elements located within the casing, one of the grinding elements being stationarily mounted in the casing, the other grinding element being supported on a rotatable shaft passing through the casing, and the rotatable shaft having operatively associated therewith a servo motor operated displacement piston for axially displacing the shaft relative to the casing, the improvement of liquid seal means cooperating with the shaft for sealing the interior of the casing from the ambient atmosphere comprising: a disc rigidly secured to the shaft, a stationary annular sealing housing surrounding the disc, the annular sealing housing being open inwardly to contain a sealing liquid which during rotation of the shaft is conveyed by the disc to form a liquid ring, the sealing housing being coupled to the casing, the sealing housing being joined to the displacement piston so that it is displaced along with the shaft displacement, and yieldable mechanical sealing means located between the casing and the sealing housing for yielding in correspondence to the housing displacement.