They are the reciprocating compressor which has piston working only in one direction the other end of the piston is often free or open from which no work is performed there is only one side compression or the upper part of the piston is used to compress the air the bottom part is open to crankcase and is not utilized for the compression of air.
Reciprocating air compressor working principle.
So classification will help you better understand the working of the reciprocating air compressor.
But according to stages the building of discharge pressure is different in each compressor.
A reciprocating air compressor works much like the engine fitted in your car motorcycle or any other machinery.
Reciprocating air compressor has also classified according to its stages.
Now that you have understood what an air compressor is its type and application.
In reciprocating air compressor as the piston moves towards the bdc the air is sucked into the cylinder from the atmosphere and when it moves towards the tdc the compression of the air starts and keeps on going and pressure increases.