Mechanical and electrical rehabilitation of two 155-ton powerhouse cranes.
Fort Randall Dam is 2 miles long and is located in South Dakota, just north of the Nebraska state line. The hydroelectric power generated each year is enough to power nearly 245,000 households.
WEMCO was hired as a Prime Contractor by the US Army Corps of Engineers to perform complete mechanical and electrical rehabilitation on two 150-ton capacity powerhouse cranes, as well as up-rate their capacity to 155-tons. The rehabilitation scope included engineering and manufacturing of all-new open gearing, bridge driveshaft, gearboxes, main and aux bull gears, new paint, new wire rope as well as a new operator’s cab complete with HMI display and modern technology. This rehabilitation was necessary to make the crane operation more user-friendly, reliable, and safe. Increasing the capacity was important for lifting heavier components when servicing the generators. This required in-depth FEA stress analysis of the hoist trolley which resulted in adding additional stiffeners and bracing to make the existing trolley rate with the appropriate amount of safety factor.
The project at Fort Randall Dam was approached with incredible foresight. When the project specification was released, it was assumed that the rehabilitation would be completed on-site at Fort Randall Dam. In an effort to decrease disruptions to the powerhouse workflow, we developed a plan to remove the cranes from the building and perform as much work as possible at the WEMCO facility in Spokane, WA. One of the obstacles that we faced was getting the cranes in and out of the building safely. When the cranes were originally installed, building access was no issue. After the original installation in the 1950s, a narrow roll-up door was installed at the facility. During disassembly and reinstallation, the trolleys had to be positioned on their side in order to fit through the door.