Lester Allan Pelton – The father of hydroelectric power

Lester A. Pelton (1829-1908) - Inventor whose invention paved the way for low-cost hydroelectric power.

Pelton was born in Vermilion, Ohio, in 1829. At age 20 he set out by foot to cross the plains and strike it rich. The first fourteen years he spent mining and wasn’t very successful. He moved to Camptonville and turned to carpentry, built homes, a school house, mine structures, and water wheels, eventually becoming a millwright.

His interest was in the water wheel and from early 1878 to 1880 he tested 40 types of wheels with different buckets leading to the discovery of the “splitter” type bucket. A contest was held with four other makers of water wheels. His wheel surpassed the second best by 19 percent. Work of this crossed the country and order for his wheel came from everywhere. The Allen Foundry, in Nevada City, California, could not keep up with the orders being received. Pelton want to San Francisco and met with Mr. Brayton of Rankine, Brayton and Co. and formed thePelton Water Wheel Company.

Later, The Pelton Water Wheel Company operated under several names and eventually became part of the Baldwin-Lima-Hamilton Corp. of San Francisco and Philadelphia.

Pelton retired in Oakland, California, where he died March 14, 1908. His ashes were in an urn at a monument to him in Maple Grove Cemetery, Vermilion, Ohio.

The Pelton wheel uses the momentum of a water jet impinging on buckets attached to the periphery of a wheel to produce power. It is a development of the primitive, so called “hurdy gurdy” wheel used in the California gold fields in the nineteenth century. Various inventors contributed to this type of water turbine, including Lester A. Pelton (1831 – 1908), who in 1880 patented the characteristic split bucket form.

Subsequent important contributions to the Pelton-wheel technology were made by W.A. Doble.

This is how it all began…

Figures 11,12 and 13 - Peltons sketches of hydro turbine

After discovery of gold in California, the mining industry flourished. Related industries also grew, such as: stampmills, crushers, logging operations, saw mills; there were blacksmith shops, machine shops and foundries. Water was the main source of power… Water wheels of various types were used, some more efficient than others. Crude jets were used to increase the power and speed of the wheel. Later, new nozzles were made of brass utilizing a higher head of water.

Changes in bucket designs brought the efficiency of the wheel to approximately 40 percent.

The equipment in the mines were increasing in size and demanded more power, and soon found the wheel was inadequate as a power source. During this period, Lester A. Pelton of Camptonville, Yuba County, California, a carpenter and a millwright familiar with water wheels and the overshot and undershot methods of driving them, began looking for another way to increase their speed and power.

In early 1878 he obtained the necessary equipment to test the various types of buckets. He spent the following two years testing thirty to forty different bucket designs. Close examination showed water splashing back against the next bucket impeding it. Many experiments were made to overcome this problem.

Solving the impeding problem?

Different stories have been told how Pelton solved the impeding problem. One as told by his friend, Jim Hutchinson, while Pelton was visiting a neighbor and shooting the breeze. His neighbor used a garden hose to drive a stray cow away. He noticed the steam of water coming from the hose hit the cow directly on the sharp bone of its nose.

The water divided as it struck, half to one side and half to the other side and none deflected back. He then realized why his experiments had failed.

Another version, as experiments were being made, a wheel being tested became off-centered on the shaft causing the water to impinge on one-half of the bucket and deflect
to one side. This resulted in increased speed of the wheel. This also caused an end thrust to one bearing. To eliminate the new problem, Pelton then alternated the buckets as shown by his sketch Figure 12 the next step was obvious, the buckets were joined and centered to split the steam as shown by hissketch 13.

The tests of the joined buckets were so surprising that Pelton took steps to obtain his patent.

With the help of James H. Hutchinson, an employee of Allen Foundry, the wheel was perfected and became a huge success. Business began to boom at the Allen Foundry, later known as the Miner’s Foundry and Supply Company, which became over burdened with orders, that were coming from everywhere. Transportation was also becoming a problem.

Pelton went to San Francisco and worked an arrangement with Brayton, one of the owners of Rankine, Brayton and Company machine shop, and organized the Pelton Water Wheel Company.

World’s largest tangential water wheel

Figure 1 - 18-foot 6-inch hydro wheel

The North Star Mining Company had acquired additional mining properties and realized the need for more power to work the additional area. After some investigation and studies, the decision was made to develop a compressed air plant.

On May 4, 1895, a contract was signed with Fulton Engineering and Shipbuilding Works of San Francisco. This provided for the manufacturer of a water wheel with the choice of either the Knight, a competitor, who also designed water wheels, or the Pelton water wheel. The Pelton people had concerns about a wheel larger than fifteen feet in diameter.

Further studies by A.D. Foote, a civil engineer, hired to design and construct the plant, E.S. Cobb, E. A. Rix and the Pelton Company determined that a wheel with a maximum diameter of 18 feet 6 inches could be safely operated. The Pelton Company guaranteed an efficiency of 85 percent at full load, an average of 75 percent from half to full load of theoretical power of water, to govern the speed of the wheel at a maximum of 120 revolutions per minute, and not raise the air pressure above 105 psi.

Foot calculated that a wheel of a 30-foot diameter was also practical, but was unable to convince the Pelton people, so the 18-foot 6-inch wheel was built (Figure 1). The pit where the wheel operated still exists in the museum. Edward S. Cobb, mechanical engineer of San Francisco, designed the wheel which was delivered to be the largest tangential wheel ever made. There were 64 buckets attached to the rim.

However, this wheel was short lived. More air was needed as more machinery was added. The Board of Directors authorized an enlargement of the plant. Experience at the plant confirmed Foote’s earlier thinking and the new 30-foot diameter wheel was constructed. It became the largest in the world.

The water wheel was built by Cobb and Hesselmeyer of San Francisco. The construction of the wheel was similar to the 18-foot 6-inch wheel built by the Pelton Company. It is constructed of steel except of cast iron, and the Risdon patented buckets, which were made of bronze. Later, the buckets were replaced with cast iron. (Pelton buckets are
presently on the wheel). The normal speed of the wheel is 65 rpm, with pressure of 350 psi and a single jet of 3/4 inches in diameter which can produce 1000 horsepower.

This wheel is in its original position, less the compressor and related equipment.

The little Pelton Demonstartor

Displayed next to the 30-foot wheel is a little 24-inch diameter wheel, the first iron wheel made and installed by Lester A. Pelton in the George G. Allen Foundry and Machine Shop, Nevada City, later to become the Miners Foundry.

It ran the machine shop, pattern shop, pipe shop and other machines. It operated under 84 pounds pressure, using water from the city mains. It was used as a demonstrator to show customers needing power drives what

This Pelton Wheel could do while using water pressure. Installed in 1980, with an overhead line shaft belted to the machines, it was used for several years until individual electric motors were installed on separate machines. This wheel was donated by the Miners Foundry and Manufacturing Co. to the Nevada County Historical Society in November 1952.

Rotor of a Pelton turbine