Fan clutch

[68 Satellite]

I was going to post in the cooling thread but put here instead.Why do some clutchs have a spring in the center?Older years? And is one better then the other if originality isn't important? Thanks

 

[Meep-Meep]

It's a thermostatically controlled clutch typically found on A/C cars. When the temp gets too hot it expands and locks up - or doesn't slip as much.