Abstract: A filter press (10) is supplied with material to be filtered by a filling pump (20) and a high pressure pump (26). Both pumps are connected in parallel and designed as eccentric worm pumps. The charging pressure is gradually raised to a final pressure without any temporary dropping so as to reduce the charging time to a minimum. In correspondence with the gradually decreasing absorption capacity of the filter press (10) first the normal speed of the filling pump (20) is lowered to a predetermined lower operating speed at unvarying speed of the high pressure pump (26). If required, then also the speed of the high pressure pump (26) is reduced. If the absorption capacity of the filter press (10) again increases, first the speed of the high pressure pump (26) is raised again to its former value and, if necessary, subsequently the speed of the filling pump (20) is increased again.