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] Integrated design saves space, reduces installation, and boosts overall efficiency. High efficiency and lower energy use with two-stage compression for heavy-duty demand. Optimized for processes needing large airflow at low pressure, cutting energy waste.
[pdf] Try to turn the compressor by hand. It should be possible to turn it around. It should turn around smoothly, without any ‘hiccups’ (be sure to completely shut down the air compressor!). Check the isolation of the motor winding.
[pdf] 
