RE: What's inside the SPICA TA?

[Hirsch <Catenary@domain.elided>]

Terry Akins wrote:

> What is contained in the thermostatic actuator? Mercury?
> How exactly does it work? I figure it works on a pressure
> principle, but I'm truly not sure.

The TA contains hydraulic fluid--essentially brake fluid.
As with most fluids, when it's heated its volume increases.
The upper TA bulb is mounted in the intake manifold and is
immersed in engine coolant. As the coolant heats, the TA
fluid expands and the piston in the lower bulb extends.
The engine coolant temp is porportional to the piston length.
So piston length essentially measures coolant temp.

Rich Hirsch

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