Adjustable-voltage control handles 250-ton crane loads at mcnary dam

Crane controls so sensitive they can regulate the movement of a 250-ton load to within 1/32 inch were tested recently at McNary Dam by the United States Army Corps of Engineers. McNary Dam is located on the Columbia River near Umatilla. Oreg. Developed by the Westinghouse Electric Corporation, the new adjustable-voltage control has been installed on the first of two 200-ton gantrycranes built by the Judson Pacific-Murphy Corporation, Emeryville, Calif. These cranes will be used to raise and lower the 126-ton spillway gates at the dam as shown in the picture. When a gate is raised, the load on the crane approaches twice the weight of the gate, because of the downward pressure of the water rushing under it. Each crane is 60 feet long, 42 feet wide, and towers 77 feet above the top of the dam. Mounted on 16 wheels, the giant cranes move along the top of the dam on rails placed 34 feet apart.