Thermostat O/T

Have anyone ever seen a thermostat that locks wide open? I pulled one out of a 3.8 ford and it has a little device that locks the baffle wide open for some reason. Maybe it came this way and the last person didn't close it before installing. ???

 

It's a relatively new thing , called "fail safes" . Believe they are made by Tru-stat.

 

What is the principle behind them?

 

It could be a Motorad thermostat that locks open once the engine has been overheated.
Here is a Youtube video showing how it works

http://www.youtube.com/watch?v=LTz4Buuy_c8

 

That is exactly the one I found. This engine must have overheated at some time.