A pneumatic pressure regulating valve, the opening of which can be automatically changed in a pressure-related manner, including a control diaphragm that is subjected to a reference pressure, to the gas pressure as well as to a governor spring, wherein a change in the differential pressure causes an adjustment of the control diaphragm and the latter itself or a closing element actuated by it changes the opening through an outflow cross-section, and wherein a structure that is arranged adjacent to the outflow cross-section on the diaphragm side forms a stop for the control diaphragm or for the closing element in the closed position of said control diaphragm. At least one preliminary stop is arranged in the pressure regulating valve such that, when the control diaphragm is moving in its closing direction, the control diaphragm or the closing element first comes into contact with the preliminary stop and that, when the control diaphragm is moving further in its closing direction, the control diaphragm or the closing element will then, while being subjected to elastic and flexible deformation or being further subjected to elastic and flexible deformation respectively, further reduces the opening and, in a final position, also comes into contact with the stop.