| 摘要 |
PURPOSE:To prevent the reverse flow of water, by a method wherein the lower end of gate body provided at its upper part with a float is rotatably installed, the one end of a wire for hoisting is connected to the side of the gate body, and a balance weight is coupled to the gate body. CONSTITUTION:When a water level on the upper stream side is increased to a plan water level, a stopper 22 is disengaged from a claw gear 21 resulting from floating of a float 18, and the claw gear 21 is rotated, and a gate body 1 falls down onto a bottom board. When a water level on the downstream side is increased, since the gate body 1 is decreased in an apparent weight by a balance weight 14 as a result of buoyancy being exerted on the float 3, the gate body is easily rotated around a hinge part 2 for floating. during a flood, the door-gate body 1 is brought into lowering, and a hook 33 at the forward end of a chain 32 is engaged with a handle 31 to lock a handle 31, and thus prevents the gate body from rotation in a rising direction. |
