Air Compressor An Air Compressor is a device that converts power (using an electric motor, into potential energy stored in pressurized air (i.e., compressed air). By one of several methods, an air compressor forces more and more air into a storage tank, increasing the pressure. When tank pressure reaches its upper limit the air compressor shuts off. The compressed air, then, is held in the tank until called into use. A reciprocating compressor or piston compressor is a positive -displacement compressor that uses pistons driven by a crankshaft to deliver airs at high pressure. The intake Air enters the suction manifold, then flows into the compression cylinder where it Air compressed by a piston driven in a reciprocating motion via a crankshaft, and then discharged.