You’ve nearly definitely seen a strain gauge someplace: on an air compressor, a steam boiler or maybe an automotive vacuum gauge. Have you ever thought a lot about how that gauge works? Magic? Elves? We’ll rip one open to search out out.
Anybody who has been studying my posts can have surmised that I like intelligent mechanisms. The Bourdon tube, which is the supply of the strain gauge’s magic, definitely qualifies.
The operation is straightforward. One finish of the curled steel tube is sealed and the opposite is related to the supply of the strain to be measured. As that strain will increase, the tube expands and straightens very barely, as if being inflated, which, basically, it’s. Because it straightens, the sealed finish strikes and pulls on the connected mechanical linkage of gears and levers.
Air Strain Gauge Linkage
By means of that gear practice, the slight motion of the tube is translated into rotation of the indicator needle. The tube, gear practice and gauge face are sized and calibrated such that the quantity of tube motion for a given utilized strain will transfer the needle to point that very same strain on the face of the gauge.
Easy and intelligent. Virtually like magic.