A fluid flow control valve is operated to close and at least partially open an aperture defined in a wall dividing the casing of the valve. A closure member covers the aperture thereby preventing a fluid communication through the wall when the valve is in a closed position, and may be rotated to either a fully or partially opened position to allow fluid communication. A means is provided for causing rotation of the closure member and includes motion transfer means for coupling an externally applied force to the closure member. An impacting member is mounted outside the casing for applying the external force by striking against an outer portion of the casing, and the means for causing rotation may include a one way clutch responsive to the striking for rotating the closure member through a predetermined angle.
A control valve having a through flow path with a closure member providing a substantially unhindered flow through the valve when in open position but closing the path substantially at right angles to the axis of flow when in closed position. A stem controls the unit closure member and is located at an acute angle to the flow path and also to the closure position of the closure member in such a manner that a multiplication of the force applied is provided by means of its geometric relation. The casing in which the closure member is located is in two parts and separable in such a way that the closure member may be easily removed and replaced by a closure member of a different shape.
