Bolt with built-in tensile strain gauge - photo and patent

[McDesign]

Check these three slides from that presentation out - the first shows just how little of applied torque actually goes into stretching the bolt - remember, a bolt is a spring that has to be stretched to work.

Second slide shows the components of a 4-lubricant comparison

Third slide shows the huge variation between applied torque (first red-marked column) and the tension generated in the bolt (second red-marked column) - only variable was the lubricant or lack thereof.

Forrest