Niels Christensen

From Wikipedia, the free encyclopedia

Niels Christensen (1865-1952) was a Danish-American inventor whose principal invention was the O-ring, the ubiquitous hydraulic seal.

[edit] Early years

Niels Christensen was born in 1865 in Tørring, Denmark. He showed an early aptitude for mechanics and apprenticed to a machinist in Vejle, Denmark. After completing his apprenticeship, he entered the Technical Institute of Copenhagen. He immigrated to the United States when he was 26 years old.

[edit] The invention

In 1933, working in his basement, he discovered by trial and error that a ring-shaped piece of rubber in a groove one and a half times long as the minor radius of the ring made a reliable, tight seal of a piston sliding in a cylinder. He applied for a U.S. patent in 1937 and it was granted two years later. After Pearl Harbor, the 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.

[edit] References

• Wise, George Invention and Technology Magazine Spring/Summer 1991,Volume 7, Issue
• [1]
• Christensen, Niels A. U. S. Patent 2,180,795 Packing Issued Nov. 21, 1939.