an operational control device is disclosed for a positive - displacement pump having a motor , means for actuating the motor , state sensor means for detecting an actual operating parameter of the pump , and operating mode means for controlling an operating mode of the pump . a first actuating mode of the operating mode means is set by the actuating means below a first operating - parameter threshold value . this mode brings about a constantly rising pump pressure in the direction of an operating - parameter setpoint value in a variable manner , which is dependent on a detected change in the operating parameter over a predefined time interval . a second actuating mode is set as normal operation to the operating - parameter setpoint value by the actuating means above the first operating - parameter threshold value . p1 is fixed or is calculated as a fraction of the operating - parameter setpoint value and / or a pump parameter correlated therewith .