Conveyor machines in the nature of conveyors; sludge collecting machines; mechanical screening/sifting systems consisting of cleaning elements like rakes, scrapes, or brushes fixed to chains which are driven by chain wheels fixed on a drive shaft, said drive shaft being driven by a motor, all sold as a unit; screening/sifting machines; machines for separating solids from liquids; water separator machines; raking systems substantially consisting of raking machines built in a trough of concrete...