Niels Anton Christensen (16 August 18655 October 1952) was a Danish-American inventor whose principal invention was the

O-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross section (geometry), cross-section, designed to be seated in a groove and compressed during assembl ...

, the ubiquitous hydraulic seal.

Early years

Niels Anton Christensen was born on a farm in Tørring-Uldum Municipality,

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

. He showed an early aptitude for

mechanics Mechanics () is the area of physics concerned with the relationships between force, matter, and motion among Physical object, physical objects. Forces applied to objects may result in Displacement (vector), displacements, which are changes of ...

and apprenticed to a machinist in Vejle, Denmark. After completing his apprenticeship, he entered the Technical Institute of Copenhagen, now the

University of Copenhagen Faculty of Science The Faculty of Science () at the University of Copenhagen houses 12 departments, including the Natural History Museum of Denmark. The faculty also encompasses several national and international research centres, and has a number of field stations ...

. In 1891, at the age of 26, Christensen immigrated to the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Work

Christensen became a leading draftsman at Fraser and Chalmers in

Chicago Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...

, a machinery manufacturer for industry, mining, and transportation. While working in Chicago, he witnessed an accident of a new electric railway, which resulted in two deaths and a number of injuries because the conductor was unable to stop the rail cars in time using the mechanical brake. Christensen decided to design and build a power brake. The Christensen air brake was successfully tested on Detroit's streetcar system, but an economic decline prevented Christensen from manufacturing and marketing the system. He worked briefly on electrical systems for Chicago's

Columbian Exposition The World's Columbian Exposition, also known as the Chicago World's Fair, was a world's fair held in Chicago from May 5 to October 31, 1893, to celebrate the 400th anniversary of Christopher Columbus's arrival in the New World in 1492. The ce ...

and then was hired by the E. P. Allis Company of

Milwaukee Milwaukee is the List of cities in Wisconsin, most populous city in the U.S. state of Wisconsin. Located on the western shore of Lake Michigan, it is the List of United States cities by population, 31st-most populous city in the United States ...

. While at E. P. Allis, he continued to develop his air brake for electric rail cars and streetcars. In 1896 he obtained financial backing that allowed him to make an experimental test apparatus. He also secured patents on the new valve mechanism. In early 1897, he founded Christensen Engineering Company, which initially operated in the Menomonee Valley at 718 Hanover. His operations were co-located with the Seamless Structural Company at the corner of Hanover and Burnham Streets.

George Westinghouse George Westinghouse Jr. (October 6, 1846 – March 12, 1914) was a prolific American inventor, engineer, and entrepreneurial industrialist based in Pittsburgh, Pennsylvania. He is best known for his creation of the railway air brake and for bei ...

had developed an air braking system for steam locomotives and felt that Christensen's invention constituted

patent infringement A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...

, suing him in December 1906.

Westinghouse Air Brake Company The Westinghouse Air Brake Technologies Corporation (WABCO) was an American company founded on September 28, 1869 by George Westinghouse in Pittsburgh, Pennsylvania. Earlier in the year he had invented the railway air brake in New York state. A ...

acquired National Electric, renaming the company the National Brake & Electric Company, which refused to pay royalties to Niels Christensen. Christensen promptly countersued, starting a 24-year legal battle that went before the US Supreme Court on three separate occasions over the rights to manufacture compressed air brake systems for streetcars. In 1933, when working in his basement, Christensen discovered by trial and error that a ring-shaped piece of

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...

in a groove one and a half times long as the minor radius of the ring made a reliable, tight seal of a

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder (engine), cylinder a ...

sliding in a

cylinder A cylinder () has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infinite ...

. He applied for a U.S. patent in 1937 and it was granted two years later. After

Pearl Harbor Pearl Harbor is an American lagoon harbor on the island of Oahu, Hawaii, west of Honolulu. It was often visited by the naval fleet of the United States, before it was acquired from the Hawaiian Kingdom by the U.S. with the signing of the Reci ...

, the United States government bought the rights to many war-related patents, and made them available to manufacturers royalty-free. Christensen was paid $75,000. When the war ended (formally in 1952) and the patent rights were transferred back to him, the patent had only four years left. Litigation resulted in a $100,000 payment to his heirs in 1971, 19 years after his death.''339 F2d 665 Jo. C. Calhoun, Jr., and Esther C. Young, Executors of the Estate of Niels A. Christensen (Deceased) v. United States'' (OpenJurist.org

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Selected listing of inventions

*Propeller (1369399)filed October 6, 1916; issued February 22, 1921 *Power controller for vehicle brakes (2150022)filed November 3, 1932; issued March 7, 1939 *Air compressor (2074980)filed October 17, 1932; issued March 23, 1937 *Brake mechanism (2197068)filed March 10, 1938; issued April 16, 1940 *Automobile wheel and brake mechanism (2172788)filed July 16, 1935; issued September 12, 1939

References

External links

Portrait of Niels A. Christensen
{{DEFAULTSORT:Christensen, Niels 1865 births 1952 deaths 20th-century Danish inventors 20th-century American inventors Danish emigrants to the United States

Early years

Work

Selected listing of inventions

References

Related reading

External links