In order to achieve a swing motion type retractable floodgate using a cost-effective torsion structure, the present invention is provided with a swing pivot support mechanism, a friction shoe, a door bottom support seat, and an operation step during a tidal flow. The support mechanism allows free rotation about three axes and restricts motion in the three axis directions, and a pulling force acts on the support mechanism. The friction shoe dissipates tidal energy during closing operations in a tidal flow to a level that prevents damage to the door. Reactive forces are endured by reducing impact forces with the flexibility and strength of the door bottom support seat. Suitable tidal energy dissipation is performed by selecting friction force strength in the operation step.

In order to achieve a swing motion type retractable floodgate using a cost-effective torsion structure, the present invention is provided with a swing pivot support mechanism, a friction shoe, a door bottom support seat, and an operation step during a tidal flow. The support mechanism allows free rotation about three axes and restricts motion in the three axis directions, and a pulling force acts on the support mechanism. The friction shoe dissipates tidal energy during closing operations in a tidal flow to a level that prevents damage to the door. Reactive forces are endured by reducing impact forces with the flexibility and strength of the door bottom support seat. Suitable tidal energy dissipation is performed by selecting friction force strength in the operation step.

An arrangement for controlling and measuring flow. The arrangement includes a fluid control barrier and a flow-measuring apparatus upstream of the fluid control barrier. The fluid control barrier includes a pair of plates for opening and closing a pipe, and the plates are movable towards a center line of the pipe to open the pipe and produce a symmetrical flow profile for the flow-measuring apparatus.

A pit gate includes a gate body which is inserted between a pool portion storing water and a canal portion connected to the pool portion and is configured to change a flow state of the water, and a seal portion (6) which is accommodated in a groove-shaped accommodation recess formed in the gate body and seals between the pool portion and the gate body. The seal portion (6) includes a low-rigidity portion (10) which is relatively easily deformed by a load according to a water pressure from the pool portion side, and a high-rigidity portion (11) which is provided on the pool portion side of the low-rigidity portion and is not easily deformed relatively by the load.

A mechanical closure device comprises an enclosure having four sides, a top and bottom and defining a discharge opening at the bottom. A floodgate assembly is interiorly removably mounted to the enclosure and comprises a pair of doors pivoted on a hinge assembly between an opened position and closed position. In the closed position, the doors seal against the flange to prevent passage of water through the discharge opening. A discharge drain assembly is preferably disposed on one door and has an opened and a closed position. An appendage is provided to facilitate opening and of the door. Upon removal, the floodgate assembly is stably positionable on a multipositionable service rack. A multipurpose tool is employed unlatching the floodgate doors and slidably removing the floodgate assembly.

A water control gate pivotable about a horizontal axis. Control may be by a combination of inflatable actuators and ballast chambers in combination with means for preventing over-rotation. Sealing between gate panels and between gate panels and abutments may be by means of seals inflated hydrostatically. The present invention is bottom hinged water control gate actuated by a combination of ballast chambers and inflatable actuators. The invention further includes an inflatable sealing means. The invention is particularly suited for use as a navigation lock gate system or as a flood control gate in a watercourse such as a navigation canal.

A water control gate pivotable about a horizontal axis. Control may be by a combination of inflatable actuators and ballast chambers in combination with means for preventing over-rotation. Sealing between gate panels and between gate panels and abutments may be by means of seals inflated hydrostatically. The present invention is bottom hinged water control gate actuated by a combination of ballast chambers and inflatable actuators. The invention further includes an inflatable sealing means. The invention is particularly suited for use as a navigation lock gate system or as a flood control gate in a watercourse such as a navigation canal.

An axis positioning mechanism serving as a rotation bearing of a flap gate includes a housing disposed at the bottom of an opening, a first rotating plate rotationally supported by the housing via a first shaft, a second rotating plate rotationally supported by the housing via a second shaft having a different axis from the first shaft, and a synchronizing rod rotationally connected to the rotating plates so as to synchronize the rotations of the rotating plates. The axis positioning mechanism further includes connecting members rotationally connecting a door base and the rotating plates with different axes. The door is laid flat with a pivot at a higher position than the axes.

A wall resident in a subterranean chamber and not obscuring a horizontal ground level view is situated between buoyant panels flanking the chamber and is configured to be passively rotationally raised out of the chamber to an upright position by one or both of the flanking panels when the panels rotationally buoy upward to form a barrier against water invading the position that the wall, chamber and panels occupy. When flood waters recede, the wall passively lowers so the horizontal ground level view is again not obscured. Provision is made for cleaning flood laden debris from the subterranean chamber to allow the wall to be operated repeatedly after recurring floods.

A dropdown flood barrier (100) is disclosed, which comprises at least one panel (102) and an associated counterweight (104), the panel configured to be movable between an elevated position and a lowered position in cooperation with the counterweight; and at least one rotatable drive (106) coupled to the panel, and is configured such that rotation of the rotatable drive enables the panel to be moved from the elevated position to the lowered position, the rotatable drive includes a brake arranged to exert a force against the rotation of the rotatable drive when a speed of the rotation exceeds a predetermined threshold, wherein in use, the rotatable drive is activated to enable the panel to controllably move under its own weight from the elevated position to the lowered position to form a barrier against flood water, the controllable movement of the panel enabled by the brake of the rotatable drive and the counterweight.