Monday, February 23, 2015

Bear Trap Dam

Diagram from US Government
The gates of a Bear Trap Dam raise up from the riverbed to increase the level of the upper pool and the flow of water is over the gates. This allows floating debris such as trees and ice to continue flowing downstream. Other gate designs such as sluice and traditional Tainter gates release the flow under the gate and thus obstruct floating debris.

The text for this diagram is:
Bear trap gates consist of two leaves. When in the lowered position, the upstream leaf overlaps the downstream leaf. The gate is raised by applying upper pool pressure to a chamber under the leaves. This pressure, sometimes supplemented with air or hydraulic cylinders, raises the dam gate. These gates generally retain a pool differential of 20 ft or less and are normally about 90 ft wide. They are ingeniously conceived but can prove difficult to maintain. Silt or sand deposits in or under the gates are particularly likely and may make it impossible to fully lower or raise the gates.

Ohio River, search for bear. This is one of those neat sites where I could spend soooo much time browsing.

Cincinnati Views: Fernbank Engineering Article
Cincinnati Views: Fernbank Dam
Cincinnati Views: Fernbank Dam with heavy water flow
Update: The Croton Dam uses a bear trap gate for its center spillway.





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