There are several different types of compressors, and many of the various compressor parts differ according to the type of compressor that is in question. There are some parts, such as the reserve tank and the pressure gauge, that are common to all compressors. Pressure relief valves, cooling fans and exhaust vents are also common compressor parts on most types of air compressors. While the basic operation of an air compressor is the same, some machines use pistons and rings mounted on a crankshaft with connecting rods to pump the air, while other compressors use a screw-type compressing unit and an impeller.
Three common types of compressors are the most common: reciprocating, rotatory and screw-type. Among these, the reciprocating type is the most common compressor. This design works much like an automobile engine. The piston is equipped with piston rings and moves up and down the cylinder by a connecting rod that is attached to a crankshaft. Bearings sandwiched between the rod and the crankshaft allow the compressor parts to work properly for years without fail. Piston rings provide a seal between the piston and the cylinder wall to allow the piston to pump or force air into the holding tank.
Special compressor parts in the form of spring-loaded valves operate by suction to allow the piston to draw air into the cylinder on the down-stroke of the piston. As the piston starts its upward journey in the cylinder, the intake valve is pushed closed and the exhaust valve is pushed open. The air is pushed through the now-open exhaust valve by the piston as it travels up the cylinder, making its way out of the cylinder and into the holding tank. Once all of the air has been pushed out of the cylinder, the spring-loaded valve closes, preventing the air from escaping from the holding tank.
This basic operation cycle is repeated in all types of compressors, albeit using different compressor parts for pumping and compressing methods. The screw-type compressor uses two inter-meshing screw assemblies that capture air between the screw-type compressor parts and drive it into the holding tank. This type of compressor uses the steady flow of air through the screw to hold air in the tank while the compressor is running. The rotary type of compressor uses a round drum, spinning off center to trap air and force it through special valves and into the holding tank.