Abstract: Every pressure vessel is connected by the agency of a connection channel to a control chamber. In both connection channels a shut-off valve is provided. The control chamber comprises a spring bellows whereby a spring counteracts a pressure force acting onto the mean area of said spring bellows. A ring is arranged on a control rod which controls the position of said shut-off valves. Upon a pressure loss in one of the pressure vessels the control rod operates the shut-off valves into their shut-off position such that upon a later pressure rise in one of the pressure vessels these shut-off valves remain closed. This ensures that upon a later pressure rise in an undamaged of the two pressure vessels such will remain separated from the damaged one. This pressure control means is preferably used in a motor vehicle having twin tires such as a truck or bus.

Abstract: A method of producing a corrugated flexible tube wherein a corrugated profiled strip having multiple corrugations is wound in a helical path such that its edges overlap and then the overlapped edges are tight welded together, preferably by electrical resistance welding, such that every welded corrugation of the resultant corrugated flexible tube is followed by at least one unwelded corrugation.