When you are working with Mother Nature, you soon realize that she will try to destroy anything you dare to use to harness her wind. From large wind-electric turbines to farm windmills, wind machines must be robust and have a means to protect themselves from high winds.
The typical water-pumping windmill uses an off-center mast pipe and an oversize tail vane to turn the blades out of the wind (furl) at high wind speeds. An adjustable spring is used to select the speed control point to furl the windmill out of the wind and to return the windmill into the wind as the wind speed decreases. Windmills are also equipped with a lever at the tower base to manually turn the windmill out of the wind and set a friction brake.
Windmill shown “furled,” or turned out of the wind (blades are parallel to the tail).