This child group gathers mechanical engineering inventions that harvest, grind or move crops and other bulk materials, or move fluids under mechanical power, including the reaper, combine harvester and threshing machine, the quern-stone, watermill, windmill, paper mill and sawmill that grind or process raw material, and the pump, suction pump, centrifugal pump, centrifuge and waterwheel that move or separate liquids. Their shared work is processing agricultural or bulk material or fluid rather than shaping metal or building structures, as distinct from the manufacturing and construction machinery gathered separately.