Air Injection Pump: Operation

Vanes rotate freely around the off-center pivot pin and follow the circular shaped pump bore. In the three vane type, vanes produce three chambers in the housing. Each vane completes a pumping cycle in every revolution of the rotor. Air is drawn into inlet chamber through a tube connected to air cleaner. The air is sealed between the vanes and moved into a smaller chamber (compression area).

After compression, the vanes pass the outlet chamber. Vanes then pass the stripper, a section of the housing which separates inlet and outlet chambers. Continuing its cycle, vane again enters inlet chamber to repeat its pumping cycle. Relief valve, located in outlet chamber, incorporates a preloaded spring, a seat and a pressure setting plug. Its function is to relieve outlet air flow if pressure exceeds a pre-set value. Metering grooves (machined into housing wall) located in both inlet and outlet chambers, provide a quiet transition from intake to compression to exhaust.