Abstract: A rotary valve actuator that effects rotary movement of a rotary valve includes a heavy plate member coupled with a linear motive source, which reciprocates the plate member between a first position and a second position. A first pair of flexible pull connectors, such as lengths of roller chain, are attached to the end of the plate member, and wrap around a wheel. At least one second flexible pull connector is disposed between said first flexible pull connectors and is attached to the other end of the plate member, and wraps around the wheel in the opposite direction of winding as for the first flexible connector.

Abstract: A rotary valve actuator that effects rotary movement of a rotary valve from 0 to 90°, or to 120°, or to 180°, or even more. The actuator includes a heavy plate member coupled with a linear motive source, which reciprocates the plate member between a first position and a second position. First and second coaxial wheels are fastened together on a single shaft and are rotatably supported tangent to one side of the plate member. A first flexible pull connector, such as a length of roller chain, is attached to the end of the plate member farthest from the linear motive source, and wraps around the first wheel. A second flexible pull connector is attached to the end of the plate member closest to the linear motive source, and wraps around the second wheel, in the opposite direction of winding as for the first flexible connector.