Big Bend Dam was constructed by the Army Corps of Engineers and is located on the Missouri River in central South Dakota. It forms Lake Sharpe which extends for 80 miles upstream to Oahe Dam. While Big Bend Dam provides for flood control, irrigation, and recreation, one of its primary purposes is to impound water to power the hydroelectric plant’s eight turbines. Flow to each turbine is regulated by three intake gates. At peak capacity the power plant produces 493,000 kilowatts of electricity.
The scope of this project included complete refurbishment of the 24 gearboxes that operate the power plant’s 24 intake gates as well as replacement of the intake deck electrical feeders and breakers. Since Big Bend is an active power generating facility, Alltech was limited to working on three gearboxes at one time so that only one turbine was required to be out of service. Once a reverse engineering process was completed by Power Engineering and Manufacturing, the gearboxes were removed and transported to their shop in Waterloo, Iowa. At the shop, the gearboxes received new worm gears, helical gears, pinion gears, shafts, bearings and oil heaters. Once the units were reassembled the original cases were sandblasted and painted with the specified aluminum paint system. Alltech’s millwrights installed the refurbished gearboxes by recoupling the motor, reassembling the brake, and completing a full alignment and backlash check to ensure smooth and reliable operation for years to come.