The machine used to produce compressed air is also called a compressor or an air compressor, abbreviated as air compressor. It is driven directly by an electric motor which makes the crankshaft rotate, moving the connecting rod and causing the piston to reciprocate, leading to changes in the volume of the cylinder. Due to the change in pressure inside the cylinder, air enters the cylinder through the intake valve via the air filter (muffler). During the compression stroke, as the cylinder volume decreases, the compressed air passes through the exhaust valve, via the exhaust pipe and a check valve (non-return valve) into the air receiver. When the exhaust pressure reaches the rated pressure of 0.7 MPa, it is automatically shut down by a pressure switch. When the pressure in the air receiver drops to 0.5-0.6 MPa, the pressure switch automatically reconnects and starts.