способ защиты ворот шлюза от навала судов включает образование встречной волны в камере шлюза, останавливающей судно перед воротами шлюза. Для образования встречной волны в районе головы шлюза устанавливают резервуары с водой, которые соединяются с камерой шлюза водоводами, а в водоводах устанавливают быстропадающие затворы с подхватами.

Заранее спасибо

затвор водовыпуска
tail gate, outlet sluice, tailgate, outlet valve, release valve

затвор водопроводной галереи (судоходного шлюза) water feed sluice

К нему присоединяется википедия

A sluice is a water channel that is controlled at its head by a gate. For example, a millrace is a sluice that channels water toward a water mill. The terms "sluice gate" and "slide gate" are used interchangeably in the water/wastewater control industry.

A sluice gate is traditionally a wooden or metal plate which slides in grooves in the sides of the channel. Sluice gates are commonly used to control water levels and flow rates in rivers and canals. They are also used in wastewater treatment plants and to recover minerals in mining operations.

A sluice/slide gate is a double-faced valve consisting of an open frame and a slide. Examples of where this type of valve is used include controlling flow (water and wastewater) at openings in tank walls and at ends of pipes. The term "slide gate" has been adopted for use by series of standards (C561, American Water Works Association) C561 is the standard for Fabricated Stainless Steel Slide (Sluice) Gates. This standard was approved in January of 2004.

This standard describes fabricated stainless steel sluice/slide gates with full aperture closure, designed for either seating or unseating head, or both, in ordinary water supply service. The stainless steel gates have non-metallic seat/seals, which may be of self-adjusting design. Some sluice gate manufacturers use ultra high molecular weight (UHMW) polyethelene seat/seals, to allow ease of movement and eliminate friction.
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Types of sluice gates

Flap sluice gate
A fully automatic type, which is controlled by the pressure head across it; operation is similar to a check valve. It is a gate hinged at the top. When pressure is from one side, the gate is kept closed; a pressure from the other side opens the sluice when a threshold pressure is surpassed.
Vertical rising sluice gate
A plate sliding in the vertical direction, controlled by machinery.
Radial sluice gate
A structure, where a small part of a cylindrical surface serves as the gate, supported by radial constructions going through the cylinder's radius. Occasionally a counterweight is provided.
Rising sector sluice gate
Also a part of a cylindrical surface, which rests at the bottom of the channel and rises by rotating around its centre.
Needle sluice
A sluice formed by a number of thin needles held against a solid frame through water pressure as in a needle dam.

The gates of a Guillotine lock work in a way similar to a sluice gate, but most canal lock gates are hinged to swing like doors.

[edit] Regional names for sluice gates

In the Somerset Levels, sluice gates are known as clyse[1] or clyce.[2][3] Most of the inhabitants of Guyana refer to sluices as kokers.

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Sluice gate located in Lodi, NJ.

поиск слова в словаре и прочих картинок занял примерно 3 минуты.
почти рекорд!

можно предположить, что речь идет о предохранительном(ых) устройстве(ах), надежно удерживающих затвор в открытом состоянии.

Например, здесь это называют «gate lock mechanism» (хотя, конечно, возможны другие варианты в зависимости от устройства этих подхватов)
http://www.trisuria.com/flood.htm

...To add the safety, we have added a gate lock mechanism to ensure that there will not be an accidental gate drop downs during electrical failure...

Вот это предложение окончательно убедило меня, что речь идет о stoppers.
.. which is not on stoppers or safely secured..