Flange manhole for self-balancing horizontal rotary cover

The present invention discloses a flange manhole for a self-balancing horizontal rotary cover. The flange manhole for the rotary cover consists of a manhole, a flange fixed at the upper end of the manhole and a rotary cover used for sealing the manhole, wherein the rear ends of the flange and the rotary cover are rotatably connected through a connecting shaft. The flange manhole is also provided with a spring cylinder balancing system consisting of a spring cylinder, a connecting piece and a spring cylinder support lug. The flange manhole for the self-balancing horizontal rotary cover is provided with the spring cylinder balancing system, and the torque formed by the tension of the spring cylinder is equal to that formed by the gravity of the rotary cover, so that the rotary cover can be balanced at any point within the range of 0-90 degrees, the opening of the rotary cover is safe, and the labor is saved.