a centrifugal separator provides for the discharge of solids by either an axial - motion scraper or a piston / extrusion assembly . the axial - motion scraper is used with hard - packed or friable solids , and includes an integral feed liquid accelerator and feed holes . the piston / extrusion assembly is used with pasty solids , and includes a piston extending into a separator bowl and having openings permitting fluid communication across the piston . after high - speed separation is complete , a centrate valve closes one end of the bowl , and the piston is moved axially in the bowl by an actuator . accumulated solids are scraped from the sides of the bowl and extruded out of the piston openings for discharge from the bowl . a bowl suspension employs a spherical mounting structure and a short , stiff spindle . a spherical portion of a bearing housing is mounted in a spherical mounting region at one end of the separator , with a cylindrical portion of the bearing housing extending along the rotational axis . a bearing and the spindle of the separator bowl are mounted within the cylindrical portion of the bearing housing . the suspension is retained by a stiff resilient ring and retaining member secured to the separator in compressive contact with the spherical portion of the bearing housing .