A vehicle spring brake having a parking brake housing that defines a parking brake chamber and a service brake housing that defines a service brake chamber. A flexible membrane separates the parking brake chamber from the service brake chamber and flexes into and out of the service brake chamber based upon a pressure differential between an air pressure in the parking brake chamber and an air pressure in the service brake chamber. A pushrod extends out of the service brake housing when the flexible membrane flexes into the service brake chamber and retracts into the service brake housing when the flexible membrane flexes back out of the service brake chamber. A control valve controls the pressure differential to thereby control movement of the flexible membrane and the pushrod.