aneroid capsule meaning

[Engineering]
"A thin, disk-shaped box or capsule, usually metallic, partially evacuated and sealed, held extended by a spring, which expands and contracts with changes in atmospheric or gas pressure. Also known as bellows."

Examples

1. As the critical altitude was passed a pressure-operated aneroid capsule operated the gearbox, which changed speed to " "'Full Supercharger " ( F . S . ) "'gear, which drove the impellers faster, thus compressing a greater volume of the air-fuel mixture.
2. Two-stage refers to the use of two impellors in American parlance . | group = nb } } on a common driveshaft in effect constituting two superchargers in series; a aneroid capsule operated the gearbox which changed up to " high blower ", driving the impellors faster, compressing a greater volume of the air-fuel mixture . | group = nb } } This second stage blower required approximately to drive it.