Automatic tightening device for hub variable-pitch bearing

The invention particularly relates to an automatic tightening device of a hub variable-pitch bearing. The automatic tightening device comprises a force arm fixing base, a speed reducer supporting plate is arranged in the middle of the force arm fixing base, a speed reducer is arranged in the middle of the upper surface of the speed reducer supporting plate, and a motor is arranged on the left sidesurface of the speed reducer; an electric cylinder supporting plate is arranged in the middle of the lower surface of the speed reducer supporting plate, an electric cylinder is arranged in the middle of the electric cylinder supporting plate, a rotating shaft is arranged at the front end of a push rod of the electric cylinder, a connecting nut is arranged between the push rod of the electric cylinder and the rotating shaft, and the rotating shaft is positioned in the reducer; and a horizontal key is arranged between the rotating shaft and the speed reducer, a force arm support and a force arm supporting plate are fi