They are powered by two counter-rotating screws that compress air as it moves through the compressor. These units are designed for continuous use, capable of operating 24 hours a day, 7 days a week.
[pdf] We specialize in high-efficiency rotary screw air compressors engineered to deliver unmatched reliability, energy savings, and durability for demanding industrial operations.Our oil-free rotary screw technology eliminates contamination risks while reducing maintenance costs, making it the ideal choice for manufacturing, automotive, and heavy machinery applications.
[pdf] Let me explain how a rotary screw element is built up. See this example picture of an oil-free screw element. Compressor element (oil-free type). Photo: Atlas Copco Of course, we see the two rotors (male rot.
[pdf] 
