Abstract: A transducer for proportionally indicating small quantities of gas flow utilizing a rolling piston in association with a flexible electrical conducting band engaging terminals within the piston chamber. Gas flows from the chamber at an increasing rate proportional to piston displacement and the transducer is characterized by its low friction operation and capability to accurately sense low rates of gas flow.

Abstract: The invention pertains to a pressure sensing transducer employing an evacuated bellows wherein sliding electric contacts are mounted upon the bellows' movable portion. The sliding contacts traverse over a printed circuit board having conducting portions defined thereon connected to electrical resistances whereby pressure variations imposed upon the bellows position the contacts upon the conducting portions to produce an electric signal. A variety of adjusting means are utilized to adjust the position of the printed circuit board to the bellows, and the "span" of the conducting portions in the direction of contact movement is selectively varied by forming the conducting portions of a wedge shape and laterally adjusting the printed circuit board.