Lester Allen Pelton (1829-1908), the inventor, and his Pelton Water Wheel.
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Lester A. Pelton was an American inventor who successfully developed a highly efficient water turbine, for a high head, but low flow of water operating in many situations. Most notable today the hydro-electric power stations. Little is known of his early life. Pelton embarked on an adventure in search of gold. He came to California from Ohio in 1850 , he was 21 years old.  In 1864 after a failed quest for gold he was working in the gold mines as a millwright, and carpenter at Camptonville, Yuba County, California.  It was here that he made a discovery which won for him a permanent place in the history of water power engineering.  In the mines, Pelton saw water wheels were being used to provide mechanical power for all things mining, air compressors, pumps, stamp mills and operating other machines.  The energy to drive these wheels was supplied by powerful jets of water which struck the base of the wheel with flat-faced vanes.  These vanes eventually evolved into hemispherical cups, with the jet striking at the center of the cup on the wheel.  Pelton further observed that one of the water wheels appeared to be rotating faster than other similar machines. It turned out initially that this was due to the wheel had come loose, and moved a little on its axle.  He noticed the jet was striking the inside edge of the cups, and exiting the other side of the cup.  His quest for improvement resulted in an innovation.  So Pelton reconstructed the wheel, with the cups off center only to find again that it rotated more rapidly.  Pelton also found that using split cups enhanced the effect. By 1879 he had tested a prototype at the University of California, which was successful. He was granted his first patent in 1880. By 1890, Pelton turbines were in operation, developing thousands of horsepower, powering all kinds of equipment. in 1889 Pelton was granted a patent with the following text.  "Pelton water turbine or wheel is a rotor driven by the impulse of a jet of water upon curved buckets fixed to its periphery; each bucket is divided in half by a splitter edge that divides the water into two streams. The buckets have a two-curved section which completely reverses the direction of the water jet striking them."
The first wheel that Pelton put to practical use was to power the sewing machine of his landlady,  Mrs. W. G. Groves in Camptonville. This prototype wheel is on display at a lodge in Camptonville.  He then took his patterns to the Allan Machine Shop and Foundry in Nevada City (now known as the Miners Foundry).  Wheels of various types and sizes were made and tested. Hydro-electric plants of thousands of horsepower running at efficiencies of more than 90 per cent were generating electric power by the time of his death in 1910.  The Pelton wheel is acclaimed as the only hydraulic turbine of the impulse type to use a large head and low flow of water in hydro-electric power stations.  Pelton wheels are still in use today all over the world in hydroelectric power plants. The Pelton Wheel Company was so successful that it moved to larger facilities in San Francisco, in 1887. Pelton went to San Francisco and worked out an arrangement with A. P. Brayton, Sr. of Rankin, Brayton and Company, and togehter they organized the Pelton Water Wheel Company. Later Pelton sold out, but stayed on as a consulting engineer and later retired Oakland
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