drum gate
Quick Summary
A drum gate is a type of floodgate used in dams to control water flow. Unlike simpler vertical-lift or radial gates, drum gates rotate backward. This rotation lowers the top of the gate, allowing a measured amount of water to flow over it.
A key advantage of drum gates is their ability to automatically regulate reservoir levels with precision, often without needing external power. One design involves a steel caisson, hinged at the dam's crest and supported by a flotation chamber downstream. Water pressure and buoyancy maintain equilibrium. Adjusting the water level in the flotation chamber rotates the caisson, controlling the flow over the gate. This mechanism can be automated using a float control device within the reservoir. Drum gates also minimize issues with ice and debris passing over the spillway.12
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