a coaxial valve includes a valve box having an inlet opening , an outlet opening , and a common flow channel . an axially movable cylindrical valve casing has an opening for a fluid inlet port and an opening for a fluid outlet port , both of which are joined up in the flow channel . a coaxially positioned shutoff mechanism located inside the valve box closes off the inlet port or the outlet port of the valve casing . to provide for axial movement , the valve casing has at least one external circular groove . the drive casing has at least one inner circular groove , which is adapted to the outer circular groove so that the inner and outer grooves are engaged , via inside ball bearings , to create a ball planetary gear and ball rotary spindle drive . the drive casing is turnable and forced to turn by a drive motor inside of the valve box .