FLAPPER VALVE CLOSURE MECHANISM

摘要

A closure mechanism for a flapper features a pinion on the ear extending from the flapper that is used to mount it for pivotal movement. A spring-loaded rack meshes with the pinion or pinions on the flapper so that when the flow tube swings the flapper open, rotation of the pinion teeth advances the teeth on the rack against the force of a spring. When the flow tube is retracted, the spring pushes the teeth on the rack in the opposite direction causing a rotational movement of the flapper toward closure in contact with a conforming seat.