The Robuschi oil-free  screw blower airend is a positive displacement machine with rotary motion, also known as “helical screw” compressor. 

It delivers constant flow (volume) and variable pressure, which means that at a given speed (rpm), the compressor airend always supply the same amount of air, independently by the pressure variation. 

The screw blower airend consists of a pair of helical profile rotors (one male rotor with 3 convex lobes and one female rotor with 5 concave lobes or “flutes”), contained in a casing.