Abstract: A system for controlling the relative rpm. of the conveyor screw of a decanter centrifuge includes a gear interconnecting the screw and the centrifuge drum. The gear has an input shaft the rpm. of which determines the relative rpm. of the screw, and a housing rotating in synchronism with the drum. The input shaft and the housing are coupled to one each of two rotary, positive displacement machines one of which is a constant displacement machine while the other is a variable displacement machine. The machines are hydraulically connected in series in a closed circuit so that a change in the displacement volume of the variable machine, at constant rpm. of the gear housing, results in a change in the rpm. of the input shaft. The variable displacement machine may be mechanically coupled to a further constant displacement machine whereby the flow rate through the variable displacement machine is reduced to the difference between the flow rates through the other two machines.

Abstract: A horizontally journalled centrifugal rotor has support bearings at its opposite end portions resting on the bottoms of notches in respective end wall elements of a frame which also includes longitudinal elements extending on each side of the rotor and fixing the end wall elements relative to each other along their entire side edges, the support bearings having flanges parallel with the end wall elements and coacting therewith to fix the support bearings against endwise movement relative to the frame. The upper edges of the end wall elements, the longitudinal elements and the bearing flanges form together an endless contact surface disposed in a single plane and in sealing engagement with a similar contact surface of a top cover for the frame.