stylistic:tone, information:classification, linguistic:paraphrasing, linguistic:translation
Pneumatic positioners

Stem movement is fed back to the beam by means of a cam. As the cam rotates, the beam pivots about the feedback axis to move the flapper slightly away from the nozzle. The nozzle pressure decreases and reduces the output pressure to the actuator. Stem movement continues, backing the flapper away from the nozzle until equilibrium is reached. When the input signal decreases, the bellows contracts (aided by an internal range spring) and the beam pivots about the input axis to move the flapper away from the nozzle. Nozzle decreases and the relay permits the release of diaphragm casing pressure to the atmosphere, which allows the actuator stem to move upward.