Abstract: A valve apparatus for controlling a pressured fluid, in which the shut-off device is force closed by the pressured fluid which is admitted into a chamber via a throttle bore. The valve is opened via a drive means, which acts directly on both a pilot valve and on the shut-off device, without the interposition of an actuating fluid. The drive means first opens a pilot valve, thereby allowing the pressured fluid to escape from the chamber and to the outlet. The drive means then opens the shut-off device. The reduction in pressure in the chamber enables a drive means of only moderate power to complete the second step of opening the shut-off device. The drive means acts directly on the shut-off device; thus the control action corresponds directly to the stroke displacement of the drive means at any particular moment.