🔍 Key Concepts

• Bourdon tube principle – what happens to the curved tube itself when internal pressure increases? • How motion from the free end of the tube reaches the pointer through the link, sector, and pinion in the illustration. • Difference between parts that sense pressure (tube) and parts that indicate pressure (pointer and gearing).

💭 Think About

• Look at the numbered parts in the illustration: which part is actually in contact with the pressure medium, and what mechanical motion does that part experience first? • If the tube were perfectly rigid and did NOT change shape, what would happen to the link, sector, pinion, and pointer when pressure was applied? • Which component, by its design, is used to transmit and amplify motion, rather than to change its calibration or set point?

✅ Before You Answer

• Be clear on which part physically deforms when pressure is applied – that is the heart of a Bourdon gauge. • Decide whether the pointer’s direction of rotation is fixed by theory, or depends on how the movement is arranged by the manufacturer. • Confirm that the set point or zero of the pointer is adjusted during calibration, not every time pressure is applied.