Forces on Lifting Beams Used with Three‐Leaf Intake Gates

At many hydroelectric plants, crane‐lowered, leaf‐type intake gate systems are relied upon to stop turbine flow after failure of the wicket gates. Unfortunately, intake gate systems of that type have a history of operating problems, such as failure of gate leaves to descend, crane overloading, and failure of the lifting beam to release. A review of that history prompted TVA to investigate the efficacy of its intake gate systems. As a starting point, new model tests of the intake gate system at Melton Hill Dam were performed in 1983, 20 years after completion of the dam. The Melton Hill system used three stacked rectangular leaves in each of three bays for closure of a unit. Each of the nine leaves was lowered into position by the same crane and lifting beam. The original design of the system had been based on model tests, which had not included behavior of the lifting beam. In field tests performed shortly after construction of the dam, the gate leaves seated properly in flowing water but the lifting beam would not release from seated gate leaves. Recommendations based on results of the 1983 model tests included changes in the lifting beam, geometry only.