Abstract: A rotary drum vacuum filter suitable for processing pulp slurries is provided with a vacuum expression belt. The invention provides a method and apparatus for tracking and controlling the belt during operation. The belt is positioned by a moveable frame for expressing filtrate from the pulp web and in operation a control unit monitors lateral movement of the belt with respect to the drum. When drifting occurs the belt is adjusted horizontally during operation to counter drift. The adjustment can be repeated as necessary. If continued drift cannot be corrected then the belt is moved vertically to an inoperative position.

Abstract: A drum structure for a rotary drum vacuum filter wherein the drum comprises a pair of conical shaped support members having concentrically arranged interconnected peripheral base portions with the apexes of the support members carried by spaced cylindrical end plates which form the end walls of the drum. Filtrate compartments are formed beneath the outer filtration surface of the drum by adjacent pairs of a plurality of spaced panels having edge portions fixed to both the support members and the end plates.