DREHKLAPPENVENTIL MIT DREHMOMENTENAUSGLEICH

A balanced-torque butterfly valve (40) incorporates a pivot mechanism (52) designed to provide for bimodal movement of the valve plate (42). The valve plate (42) has a cavity (54) formed therein to receive the pivot mechanism (52) and to accommodate translational movement of the valve plate relative to the mechanism. This eliminates fluid dynamic effects that would be produced if the mechanism were positioned in the flow path (44) and external to the valve plate (42). The pivot mechanism (52) comprises a center shaft (70) rotatable relative to the valve plate (42), and a carrier shaft (72) which is in fixed rotational relation to the valve plate (42) and extends through the mounting body (46). This permits both translational movement of the valve plate (42), and detection of its rotational position from a vantage point outside of the flow path (44). In addition, the carrier shaft (72) cooperates with bearings (104) to minimize load-bearing requirements of rack and pinion gears (64, 66, 116, 118) which are used to convert rotational movement of the center shaft (70) to translational movement of the valve plate (42).