When the inlet/unloader valve is open, the air enters the compressor screw element. The screw element works like a pump and it compressed the air. During this process, oil is injected in the element. The oil is there to cool the air, as the air gets very hot during compression.
[pdf] The DHV-G/A series features a permanent magnet variable frequency single-stage compression screw air compressor that delivers stable air pressure with no impact during startup. It boasts variable flow control and excellent alternating current power supply voltage adaptability.
[pdf] An auger drill is a spiral-shaped tool. Its main function is the drilling of holes in the ground and other materials - or surfaces such as ice, wood, etc. The design of an auger depends on the kind of material it's meant to drill into, hence there are different types of auger drills. Auger drills come in varying sizes and can drill holes up to a depth of 95 feet below the ground. They are known to be quite versatile, saving time and energy during construction work or even personal projects. T.
[pdf] 
