It puts the compressor into an unload state once cut outpressure is reached, and back into a loaded state once the cut inpressure is reached. Depending on the exact setup, a line from oneof your air tanks will go to your governor. When the cut outpressure (between 120 and 135 psi) is reached, a valve opens in thegovernor to send air to to compressor and to the air drier. Thiscloses the discharge valve on the compressor, sending it into anunloaded state, and also starts the air drier purge cycle.