An average rotary screw air compressor has two interlocking helical rotors contained in a housing. Air will come in through a valve, typically known as the inlet valve and can be taken into the space between your rotors. As the screws change, they reduce the level of the air, thus increasing the pressure.
The center of an air compressor may be the screw element which can be called air-end. The air-end can be the most important part of any screw-type compressor. It’s that section of the machine where the actual compression takes place. It is the center of the rotary screw air 
A Rotary Screw Surroundings Compressor is a compressor that uses a rotary-type positive displacement system, called a rotary screw, air-end. … Rotary Screw Compressors also use two inter-twined helical designed screws, known as rotors, to compress the air.