Transducer

A device for transferring power which is generated in one system to another system in the same or a different form, e.g., electrical to mechanical.
Any device that converts an input signal into an output signal. Used to actuate electric or vacuum servo motors in an automatic temperature control system.
Device turned on by change of power from one source for purpose of supplying power in another form to second system. See also negative transducer EGR valve