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<br /> <br /> <br /> <br />11 <br />require relatively small motors to operate and can, in <br />some cases, be hydraulically regulated by means of <br />floats and counterweights, with no hoist needed. <br />However, they are generally not cost-effective for <br />small applications due to the level of design required. <br />Tainter gates usually require regular maintenance to <br />the gate guides, lifts, and trunnion rotation anchor <br />points to limit the risk of failure. (See the 1995 tainter <br />gate failure on Folsom dam). <br /> <br />Photo 2: Tainter Gates <br />Fixed Wheel Gate: These gates employ a more robust <br />system suitable for operating in smaller spaces (e.g., <br />conduits) and in higher head conditions. They can <br />easily be used under high pressure and are preferred <br />for submerged applications. In cold climates, they are <br />also chosen over tainter gates for surface applications <br />for the good resistance they offer to ice loads and <br />floating debris, as well as operability under high stress. <br />Relatively large motors and hoist systems are required <br />to overcome the weight and friction of a fixed wheel <br />gate. The presence of wheels requires regular testing <br />and operation to ensure proper operation. Fixed wheel <br />gates can be installed with a stoplog system <br />immediately upstream to facilitate maintenance. <br /> <br />Photo 3: Fixed Wheel Gate <br />Sluice Gate: Similar to fixed wheel gates, sluice gates <br />(also called slide or knife gates) consist of a vertical <br />plate installed through the water passage; however, <br />the contact with the structure is a frictional interface <br />rather than rolling wheels. Vertical contact is made by <br />a steel or bronze plate sliding against the guide. Bronze <br />is more expensive than steel but also more durable <br />and reduces the friction during operation. The main <br />advantages of sluice gates are their low cost and <br />simplicity. Maintenance due to the wheeled system is <br />eliminated. The induced friction restricts usage to <br />small open areas or low head applications. A sluice <br />gate is a good choice in situations where it is operated <br />infrequently or for small systems. See reference [12] <br />for more information <br /> <br />Photo 4: Angled Intake Sluice Gate Parallel with Upstream <br />Face of Dam <br /> <br />Figure 1: Vertical sluice gate, Cylinder operated