Combined hydrostatic/hydrodynamic bearing system for grinding apparatus

Claim 1

In a pulp refining apparatus in which the pulp raw material is ground in a grinding space defined between at least one pair of relatively rotating grinding members and in which at least one of said grinding members is carried by an axially displaceable rotatable shaft, a bearing system comprising combined hydrostatic/hydrodynamic (a) at least one rotatable piston defined between two opposed pistons ends mounted on said rotatable shaft to rotate therewith (b) at least one cylindrical housing defining at least one pressure chamber circumferentially surrounding said at least one cylindrical piston permitting the same to move axially in said pressure chamber; (c) means for applying a hydrostatic stabilizing force on said shaft in an axial direction by supplying a fluid pressure medium to at least one of said piston ends to continuously counteract fluctuating axial thrust forces exerted on said shaft during the grinding operation to thereby maintain a predetermined clearance range of said grinding space with consequent generation of fluctuating pressure differentials between said opposed piston ends; and (d) means for generating a hydrodynamic stabilizing force on said rotating shaft in a radial direction comprising passage means allowing said pressure medium to flow under pressure between said opposed piston ends in said at least one pressure chamber by the effect of said pressure differentials and the effect of the centrifugal force imparted to said fluid pressure medium by the rotation of said at least one cylindrical piston within said at least one pressure chamber.