Abstract: A filter has an endless filter cloth, which passes under a slurry feed and over a suction box, through which suction is applied to the cloth to remove liquid from the slurry. The cloth is driven by a roller, around which the cloth is trained, linked to a motor. The operation of the motor is controlled by a central device so that the cloth is advanced incrementally, the length of advance of an increment being predetermined and selected to satisfy operating requirements. The control device can also provide for regular acceleration and deceleration.