Directly driven by motor compressor, crankshaft produce rotary motion, drive the connecting rod to make the piston reciprocating motion, cylinder volume change. Due to the change of pressure in the cylinder, through the inlet valve make the air through the air filter (silencer) into the cylinder, in the compression stroke, due to the cylinder volume reduction, the role of compressed air through the exhaust valve, the exhaust pipe, one-way valve (check valve) to storage tanks, when the exhaust pressure to achieve the rated pressure of 0.7 MPa is controlled by a pressure switch and automatic stop. When the reservoir pressure dropped to 0.5-0.6 MPa pressure switch automatically start.