Abstract: A throttling ball valve with an array of closed spaced horizontal plates secured across the flow passage through the ball. The leading edges of the plates are streamlined so that the flow stream will be divided into a plurality of laminar flow streams, each with a boundary layer across a surface of the plate. Energy is absorbed in the boundary layer phenomenon. The array of horizontal plates is preferably contained in a cylindrical sleeve which is inserted and secured into the cylindrical flow passageway through the valve ball.

Abstract: A hydraulic system for precise positioning of a control device, such as a valve actuator. A double-acting, hydraulic cylinder, which operates the control device, is held in any set position by a hydraulic lock ensured by one-way check valves which prevent interflow between the chambers on opposite sides of the piston. Occurrence of a signal indicating a need to change position activates one of two three-way directional control valves allowing exhaust flow from the appropriate cylinder volume. Connected in parallel in the exhaust line is a plurality of on-off valves, each having a flow capacity that is some multiple of that of the next smaller valve, e.g. twice as large. This provides a wide range of distinct and precise flow capacities to provide close and instantaneous control over rate of movement of the positioning device.