Abstract: A combined spool and rotary disc valve has a quick emergency exhausting means. In normal operation, the spool valve allows pressurized fluid to flow between an inlet and a choice of one or more outlets. When quick emergency exhausting of all of the outlets is desired, the spool valve is disposed such that all the outlets communicate through an exhaust slot in the rotary disc valve, through an interior passageway of the cylinder, further through a second part of the spool valve into a different interior passageway which leads to an annular channel which is exhausted by one or more exhaust openings through the barrel housing. The normal flow of pressurized fluid can also be reversed such that, with blockage of all exhaust openings in the barrel housing, the rotary control valve becomes a mixing valve.