Rocking piston compressor technology

Rocking piston compressors are a variation of standard piston compressors. Instead of having a separate piston and rod that are connected via a wrist pin, rocking piston compressors utilize a solid cast piston rod that incorporates both the piston and rod. A flexible cup seal attached to the piston rod provides a seal between the piston rod and cylinder and also guides the piston rod as it is driven up and down in the cylinder. The piston rod is mounted to an eccentric bearing assembly, which converts rotary motion from either an AC or DC motor into the linear motion that drives the piston within the cylinder. 

As the piston moves down, a vacuum is created above it allowing outside air at atmospheric pressure to push open the inlet valve and fill the area above the piston. As the piston moves up, the air above it compresses forcing the inlet valve shut and pushes the discharge valve open. The compressed air then moves from the discharge port into the air line or the receiver tank depending on the system design. With each stroke, more air enters the air line or receiver tank and the air pressure rises.