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U.S. Patent 1,520,706 · C. C. Farmer · Westinghouse Air Brake · granted the same day as 1,520,705

Centrifugal Dirt Collector — spin the air, drop the grit

drag — rotate · pinch/scroll — zoom
Collector 0 100 GRIT AT VALVE
Dirty air spirals down the funnel: heavy grit slings to the wall and drops; clean air escapes up the center pipe.
Blue = air · amber = grit. Particle paths schematic; the cyclone principle is the real one.