Weight Driven Cooling
With the recent heat wave in the Northwest, there was a post by a member of a FB group I'm in asking about mechanical fans. In the thread this example of a weight driven fan was offered.
I can see how this works. The heavy weight pulls down and then the wire, attached to the gear (in a spool around the gear with the handle) slowly unwinds, turning the gear. The gear train then increases the rotations as it steps it up. What I can't figure out what prevents the fan just running full out until the weight is at its downward travel limit? Seems like you would need some sort of alternating cam lock, like what a old clock mechanism has. Or is it just the natural air resistance of using such large blades?