The screw compressor cylinder is equipped with a pair of intermeshing spiral female and male rotors. Both rotors have several concave teeth, and the two rotate in opposite directions. The main rotor (also called a male rotor or a convex rotor) is driven by an engine or an electric motor (mostly driven by an electric motor), and the other rotor (also called a female rotor or a female rotor) is driven by the oil film formed by the main rotor through oil injection. Or driven by synchronous gears at the main rotor end and the female rotor end. So there is no metal contact in the drive (theoretically).

The length and diameter of the rotor determine the compressor displacement (flow) and discharge pressure. The longer the rotor, the higher the pressure; the larger the rotor diameter, the greater the flow. The groove of the spiral rotor is filled with gas when passing through the suction port. When the rotor rotates, the rotor groove is closed by the casing wall to form a compression chamber. When the rotor groove is closed, the lubricating oil is sprayed into the compression chamber to seal. Cooling and lubrication. When the rotor rotates and compresses the lubricant + gas (referred to as the oil-gas mixture), the volume of the compression chamber decreases, and the oil-gas mixture is compressed toward the exhaust port. When the compression chamber passes through the exhaust port, the oil and gas mixture is discharged from the compressor, completing a suction-compression-discharge process. Each rotor of the screw machine is supported by an anti-friction bearing, and the bearing is fixed by an end cover near the end of the rotating shaft. The intake end is supported by a roller bearing, and the exhaust end is supported by an opposed cone roller bearing, which is usually the exhaust end bearing to position the rotor, that is, a thrust bearing, which resists axial thrust and bears radial load. Provide the necessary minimum clearance for axial operation. The working cycle can be divided into three processes: suction, compression and exhaust. As the rotor rotates, each pair of mutually meshing teeth completes the same work cycle one after another.