Did you place it on an existing rail, so that input and output are connected? It's supposed to work like gas filter (but with possibility to filter more than one element) Not sure if I understood you correctly, so I'm gonna just visualize it: Everything goes in from the left side. Things selected in the filter go out from the middle, and the remaining things go out through the green output (pass through). The rails behind the filter shouldn't be connected to each other, just to the filter. I haven't changed the logic of the conveyor flow -- the outputs are marked as a receiver and a source. Do you mean a situation like this? "Pulling" things out of the main loop? Just tested it in game - before turning on the filter the ore went up and left. After turning the filter on, everything was 'sucked in' by the filter and filtered:   Could you make sure that you haven't accidentally connected input with outputs on the filter, and if not, show me your setup?