Abstract: A step wise drive system is mounted on a plate with a flat upper surface, in a light proof environment. The drive system drives a carriage via a motor actuating an endless screw which co-operates with the runner nut connected to the carriage. At the other end, the carriage comprises a motor which in turn co-operates with an endless screw acting on runner nut. The runner nut bears lateral slides connected to a film holder unit. Finally, the film holder unit is movable in a sliding fashion on a rail connected to the carriage. In this way, the film holder unit is connected to the second runner horizontally in X and Y directions and free vertically relative thereto. It can therefore slide on the upper surface of the plate with a dry fit, permitting excellent positioning of the microfiche for taking shots.

Abstract: A filter has a vertically disposed housing, a support plate and vertical filter elements fixed at their upper ends to the support plate and supported thereby in the housing. A water outlet tube passes through the center of the support plate and exits at the base of the filter. The water outlet pipe is connected to the support plate in leak-tight manner and the portion of the filter located above the support plate is removable.

Abstract: A circular decanter includes a stationary hollow column rotatably supporting a bridge which spans the decanter. A trough is integral with the bridge and rotates therewith, whereby sludge drawn by vacuum from the bottom of the decanter is collected in the trough. A sludge evacuation duct is positioned centrally within the hollow column. That portion of the trough which is closest to the column is formed as a siphon having an upstream branch extending downwardly into the sludge collection chamber of the trough and a downstream branch extending downwardly into the sludge evacuation duct. An electric motor for rotating the bridge, trough and siphon is positioned above the column and includes rotating elements attached to the siphon and non-rotating elements. The power supply cables for the electric motor are led upwardly through the column, the sludge evacuation duct and the downstream branch of the siphon and are enclosed within a stationary casing and tube.

Abstract: A system for the dehydration of residues such as sludge includes first and second endless filter belts which move at identical speeds in endless paths. A residue to be dehydrated is supplied between the two filter belts which pass together in alteration around a perforated drum and a plurality of rollers. Two of the rollers are positively driven at identical speeds but in opposite directions to thereby drive the two filter belts at identical speeds. Both filter belts are simultaneously and identically tensioned to control the pressure exerted by the filter belts on the residue during passage thereof around the drum and rollers. A supplemental pressing assembly presses the filter belts and residue against the perforated drum at a uniform pressure regardless of the thickness of the residue. The supplemental pressing assembly is simultaneously controlled by the same fluid source which controls the assemblies which tension both of the filter belts.