Mick McCann and N. Christian Porse
June 19, 2012 | 1 Comments
What happened next must have been a shock. The bearing failed completely on the first attempt at operation and wiped off the protective babbitt coating. However, Dr. Kingsbury knew his bearing could work perfectly for power generation. He shipped the parts back to Westinghouse Machine, where the bearing was polished and returned. Kingsbury realized that all of the services needed to be completely flat. Over several long days and nights in June , Dr. Kingsbury and a crew reinstalled the bearing.
The Kingsbury thrust bearing carried a running load of 405,000 pounds on a 48-inch thrust collar in the 10-MW unit. The Kingsbury bearing, resting on a slim wedge of oil that never allowed metal to touch metal, minimized wear to an almost unbelievable degree.
"When Dr. Kingsbury came with his invention and technology, the application led to increased availability of the equipment, which was vital. With the Kingsbury bearing development and installation, it increased the reliability of the equipment and allowed for successful operation of the Holtwood plant. All 10 of the original bearings have been, in fact, running for 100 years with very successful operation and very few problems. The Kingsbury bearing also resulted in development of much larger equipment that was installed subsequently at various power plants throughout the U.S. and the world," Porse says.
Dr. and Mrs. Kingsbury attended the 25th anniversary celebration at Holtwood. Unit 5 was taken out of service and the thrust bearing was disassembled. One of the thrust bearing shoes was removed from the unit for inspection and measurement of wear to determine the remaining life of the bearing. Through those measurements, it was determined the life was about 1,300 years before the thrust bearing would wear out or require replacement.
The bearing received a special honor in 1987. ASME established a History and Heritage Program in 1971 to recognize significant artifacts, locations and items noteworthy of engineering significance, and the Kingsbury bearing in Unit 5 was designated as the 23rd International Historic Engineering Landmark in June 1987 as part of that program.
Kingsbury Bearing Applications Expand
Kingsbury's first offer for a licensing agreement was with Westinghouse Machine to install bearings in its steam turbines. But the production of electricity marked Kingsbury's beginnings and still figures prominently in Kingsbury's business after 100 years. Kingsbury entered the hydroelectric generating market just in time to jumpstart the Kingsbury bearing sales and boost electric generators onto a new plateau of greater capacity and longevity at less cost.
Yet most historical accounts of the development of electric generation do not mention the Kingsbury bearing by name. It was subsumed as a part among other parts in a larger machine. It helped other machines do their work. By itself it did no work. Historical accounts do note the need in the early 20th century for generators to withstand tremendous spinning forces without wear, to avoid overheating, and to minimize friction's dissipation of generated power. And the Kingsbury thrust bearing solved those problems, but first inventors and entrepreneurs had to build the machines needing the solution.
During the next decades, electricity in U.S. cities transformed work, home and everything in between. Generators sent electricity to new city railroads and street lights at first. Then manufacturing began to accelerate. With electric motors installed, mills could move away from the crowded banks of prime rapids and falls to more remote locations where they could spread out, nearer perhaps to labor, their raw materials or transportation centers. Textile mills, some of the first adopters of electricity, became less fire-prone, cleaner, cooler and able to operate at night. Steel mills became major users, replacing workers with machines.
Demand increased exponentially. The phenomenon was so striking that the U.S. government tried to measure and report the change. In 1899, the year Kingsbury started teaching at Worcester Polytechnic Institute, there were 16,891 machines in U.S. factories turning out a total of less than 500,000 horsepower. By 1909, while the Kingsbury thrust bearing was waiting for a patent, 388,854 electric motors in U.S. factories yielded 4,817,140 horsepower.
Eventually, power companies turned to supplying domestic electrical consumption in urban and suburban centers, first with electric lighting and then with household appliances. Efficiency crept into the home from the factory, and time rather than the task to be done defined the work period. Households changed from places of production to places of consumption. Generators struggled to supply more electricity to domestic and commercial customers over greater distances. Now Kingsbury's bearing was needed. After the success at McCall's Ferry, others soon followed. A 1952 Kingsbury catalog looked back, observing, "Acceptance of the pivoted shoe thrust bearing was rapid, and there followed a spectacular growth in the size and power of vertical hydroelectric generators, until then handicapped by lack of thrust bearings capable of supporting loads of the order of hundreds of tons."
Kingsbury thrust bearings were retrofit on existing machines and included in new ones. Sites included the Niagara Power plants started in the 1890s, Hoover Dam built in the 1930s, and Tennessee Valley Authority dams following that, as rural electrification progressed. The TVA turbines in the 1930s carried a running load of more than 2 million pounds, five times that carried by the original Holtwood bearing.
Today, Kingsbury bearings are at work all over the world in oil refineries, power generation stations, pumping stations and ship propulsion.
Mick McCann is vice president of sales and marketing for Kingsbury Inc. Chris Porse, P.E., MBA, is site supervisor for PPL's Holtwood hydroelectric plant.
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