Inlet Phase - The male and female rotors rotate counter to each other. As the lobes of each rotor travel past each inlet port, air is trapped between consecutive lobes and the cylindrical casing. The air moves axially (forward) throughout the case and fill the inner-lobe space between adjacent lobes.

Compression Phase - As the rotors mesh, the air is trapped between the rotors and the casing. Continued rotation progressively reduces the space occupied by the air causing compression.

Discharge Phase - Compression continues until the inner-lobe space becomes exposed to the outlet port, through which the air is discharged into the manifold.

The compression sequence continues on all rotor segments simultaneously. Timing gears synchronize the rotors. The rotors do not touch the casing or each other thus assuring long life, consistent performance and low parasitic losses.