Abstract: A pressure regulator for regulating valves and other pressure-reducing mechanisms having control means including a stem which is actuated to close the valve or mechanism by means of a diaphragm built into the pressure regulator. The side of the diaphragm opposite the stem is subjected to the reduced pressure on the downstream side of the valve or mechanism and is biased by a force, e.g. a spring force, which balances the reduced pressure. The stem of the control means is passed through a safety slide member axially movable in the housing of the pressure regulator, and the stem is provided with a locking ring at a point between the slide member and the end wall of housing of the pressure regulator, corresponding to the predetermined lift.