Patent ID: 7334994

Claim:
A sail restraint for a vertical axis wind turbine comprising: (a) an arm extending from a horizontal arm of a vertical axis wind turbine; (b) a rotatable joint secured at the end of said arm; (c) a main vertical member secured to said rotatable joint; (d) a mainspring secured at one end to said arm and at the other end to said main vertical member; (e) a rotatable flapper joint secured to said main vertical member; (f) a flapper secured to said rotatable flapper joint; (g) a flapperspring secured at one end to said flapper and at the other end to said main vertical member; whereby wind speed that is not excessively high pushes a sail frame of a vertical axis wind turbine against said flapper, said mainspring does not expand sufficiently to allow said sail frame to pass by said flapper, causing the wind turbine to rotate; and whereby when excessively high wind speed pushes a sail frame of a vertical axis wind turbine against said flapper, said mainspring expands sufficiently to allow said sail frame to pass by said flapper, placing said sail frame and its sail into the safety of a feathered position on the wind turbine, and whereby, with the sail frame and sail in the feathered position, when the wind speed eventually falls below excessive levels, and the wind eventually pushes said sail frame against said flapper, said flapper-spring expands sufficiently to allow said sail frame to pass by said flapper, and into the normal operating position of the wind turbine.