The tail-water adjustment with recumbent flap gate has properties of fast response and wide adjustment,which is a common method of controlling tail-water in an unsteady hydraulic model.

Difference-type tailgate can overcome waterlevel shaking of the traditional pirated tailgate,and adjustment difficulty in low flow of the grid type tailgate.

Path of instantaneous center of hydro-automatic flap gate and its influences on gate s stability;

The design background,technical specialty and structure of portal turn plate idler roller are introduced,and the roller working fundamentals in normal belt running,gliding and braking conditions.