Section of 1920's Ingersol Rand Compressor. The machine was double acting so as air was drawn in through the lower valve on one side of the piston, the air on the other side of the piston was being compressed and forced through the upper valve into the four inch delivery pipe. The running speed was 325 revolutions per minute delivering around 460 cubic feet of air per minute at 100 pounds pressure.                    BACK                         Home page