Thermostat Question, How does it work? Options

[pbanders]

While I may have done a transistor-by-transistor analysis of the ECU and used pSpice to simulate the injector driver circuit, I've never done squat with my thermostat system. Basically, it works, so I leave it alone.

But I'm curious, how do the bellows work? When the car is hot, the bellows expand, and the cable tension is released. Is there an internal spring? Something about wax? Help me out here, thanks.

[emerygt350]

I ripped my old one apart pulling it out of the car, I think it is a bimetal design perhaps? There was no 'wax' inside the bellows. Or perhaps I let all the magic smoke out when I ripped it open with my pliers.... Seemed more like a metal expansion contraction type device. Not a spring inside though, unless it is contained within the bellow portion. I think. I was kind of pissed at it for how stuck it was.