Abstract: A proportional pressure regulator assembly having a main body with a first inlet adapted for fluid communication with supply of positive pneumatic pressure, a second inlet adapted for fluid communication with a supply of negative pneumatic pressure, an outlet adapted for fluid communication with a pneumatically actuated device, and an exhaust port is provided. A fill regulator valve is included that is adapted to regulate the supply of positive pressure. A vacuum regulator valve is included that is adapted to regulate the supply of negative pressure. An exhaust valve is included that is operable to exhaust pressure from the outlet. A control circuit assembly is also provided that is adapted to receive a command signal and a feedback signal and to regulate the amount of positive pneumatic pressure through the fill regulator valve or the amount of negative pneumatic pressure through the vacuum regulator valve in response to the feedback signal.