A valve consisting of a disk rotating on an axis across the diameter of a pipe to regulate the flow, as in the throttles of many engines
a valve in a carburetor that consists of a disc that turns and acts as a throttle
A valve consisting of a pair of semicircular plates that are attached to a spindle across a pipe and hinged to allow flow only one way
A butterfly valve is a valve which can be used for isolating or regulating flow. The closing mechanism takes the form of a disk. Operation is similar to that of a ball valve, which allows for quick shut off.
(Butterfly Valves) A valve consisting of a cylindrical body with a rotating vane to control flow. Tight Shutoff is obtained by an elastomer body liner into which the vane seats.
a mechanism that puts something into automatic action
An actuator is a mechanical device for moving or controlling a mechanism or system. It takes energy, usually transported by air, electric current, or liquid, and converts that into some kind of motion.
(Actuators) Devices that perform the actual work commanded by the on-board computer. Actuators can be in the form of a motor, relay, switch, or solenoid.
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Bottom side. Showing the butterfly valve and the actuator linkage. This is what rattles and is probably leaking.