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Ball Bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling they have a much lower coefficient of friction than if two flat surfaces were sliding against each other. Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races. History Although bearings had been developed since ancient times, the first mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicycle Mechanic
A bicycle mechanic or bike mechanic is a mechanic who can perform a wide range of repairs on bicycles. Bicycle mechanics can be employed in various types of stores, ranging from large department stores to small local bike shops; cycling teams, or bicycle manufacturers. Classification and wages The New York State Department of Labor describes bicycle repair as a "realistic" occupation, meaning an occupation that would be enjoyed by somebody who likes "practical, hands-on problems," dealing with "real-world materials like wood, tools, and machinery," and one that "does not involve a lot of paperwork or working closely with others." They classify it as a job that "usually requires a high school diploma and may require some vocational training or job-related course work. In some cases, an associate's or bachelor's degree could be needed. Employees in these occupations need anywhere from a few months to one year of working with experienced employees." They indicate an annual wage in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sven Gustaf Wingqvist
Sven Gustaf Wingqvist (10 December 1876 – 17 April 1953) was a Swedish engineer, inventor and industrialist, and one of the founders of Svenska Kullagerfabriken (SKF), one of the world's leading ball bearing and roller bearing makers. Sven Wingqvist invented the multi-row self-aligning ball bearing in 1907. Chronology *1876: Born December 10 in Kumla Municipality south of Örebro, Sweden. His parents are railway station inspector at Hallsberg S. D. Wingqvist and Anna Lundberg. *1894: Graduated from Rudbecksskolan in Örebro (Örebro Technical Elementary School). *1899: Wingqvist became employed as an operating engineer at Gamlestadens Textile Industry in Göteborg. He worked here for many years to find a solution to the problems with frequent break downs in the ball bearings for the main drive shafts. This was caused by the ground conditions, as the factory was built on clay. The shaft bearing supports moved some fractions of millimeters from time to time, hardly measurable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-aligning Ball Bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling they have a much lower coefficient of friction than if two flat surfaces were sliding against each other. Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races. History Although bearings had been developed since ancient times, the first mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longitude (book)
''Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time'' is a best-selling book by Dava Sobel about John Harrison, an 18th-century clockmaker who created the first clock (chronometer) sufficiently accurate to be used to determine longitude at sea—an important development in navigation. The book was made into a television series entitled ''Longitude''. In 1998, ''The Illustrated Longitude'' was published, supplementing the earlier text with 180 images of characters, events, instruments, maps and publications. Problem of longitude Determining longitude on land was fairly easy compared to the task at sea. A stable surface to work from, known coordinates to refer to, a sheltered environment for the unstable chronometers of the day, and the ability to repeat determinations over time made for great accuracy. For calculating longitude at sea however, early ocean navigators had to rely on dead reckoning, or if in sight of land, coastal nav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Harrison
John Harrison ( – 24 March 1776) was a self-educated English Carpentry, carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the History of longitude, problem of calculating longitude while at sea. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved was considered so important following the Scilly naval disaster of 1707 that the Parliament of Great Britain, British Parliament offered financial rewards of up to £20,000 (equivalent to £ in ) under the 1714 Longitude Act. In 1730, Harrison presented his first design, and worked over many years on improved designs, making several advances in time-keeping technology, finally turning to what were called sea watches. Harrison gained support from the Board of Longitude, Longitude Board in building and testing his designs. Toward the end of his life, he received recognition and a reward from Parliament. Harri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Conrad (inventor)
Robert Conrad (born Conrad Robert Falk; March 1, 1935 – February 8, 2020) was an American film and television actor, singer, and stuntman. He is best known for his role in the 1965–1969 television series '' The Wild Wild West'', playing the sophisticated Secret Service agent James T. West. He portrayed World War II ace Pappy Boyington in the television series '' Baa Baa Black Sheep'' (later syndicated as ''Black Sheep Squadron''). In addition to acting, he was a singer and recorded several pop/rock songs in the late 1950s and early 1960s as Bob Conrad. He hosted a weekly two-hour national radio show (''The PM Show with Robert Conrad'') on CRN Digital Talk Radio beginning in 2008.''The PM Show with Robert Conrad'' crntalk.com; accessed January 11, 2016. Early life Conrad was born Conrad Robert Fa ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry (the property of an object being invariant to a transformation, such as reflection). Symmetry is an important property of both physical and abstract systems and it may be displayed in precise terms or in more aesthetic terms. The absence of or violation of symmetry that are either expected or desired can have important consequences for a system. In organisms Due to how cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension. Louis Pasteur proposed that biological molecules are asymmetric because the cosmic .e. physicalforces that preside over their formation are themselves asymmetric. While at his time, and even now, the symmetry of physical processes are highlighted, it is known that there are fundamental physical asymmetries, starting with time. Asymmetry in biology Asymmetry is an important and widespread ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Nitride
Silicon nitride is a chemical compound of the elements silicon and nitrogen. is the most thermodynamically stable and commercially important of the silicon nitrides, and the term "silicon nitride" commonly refers to this specific composition. It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot . It is very hard (8.5 on the mohs scale). It has a high thermal stability with strong optical nonlinearities for all-optical applications. Production Silicon nitride is prepared by heating powdered silicon between 1300 °C and 1400 °C in a nitrogen atmosphere: :3 Si + 2 → The silicon sample weight increases progressively due to the chemical combination of silicon and nitrogen. Without an iron catalyst, the reaction is complete after several hours (~7), when no further weight increase due to nitrogen absorption (per gram of silicon) is detected. In addition to , several other silicon nitride phases (with chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceramic
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, and brick. The earliest ceramics made by humans were pottery objects (''pots,'' ''vessels or vases'') or figurines made from clay, either by itself or mixed with other materials like silica, hardened and sintered in fire. Later, ceramics were glazed and fired to create smooth, colored surfaces, decreasing porosity through the use of glassy, amorphous ceramic coatings on top of the crystalline ceramic substrates. Ceramics now include domestic, industrial and building products, as well as a wide range of materials developed for use in advanced ceramic engineering, such as in semiconductors. The word "'' ceramic''" comes from the Greek word (), "of pottery" or "for pottery", from (), "potter's clay, tile, pottery". The earliest kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrome Steel
Chrome steel is one of a class of non stainless steels such as AISI 52100, En31, SUJ2, 100Cr6, 100C6, DIN 5401 which are used for applications such as bearings, tools, drills and utensils. Popular culture The term was used in both the original 1933 version, as well as the 2005 remake, of ''King Kong''. When Kong is brought to New York City, he is chained with this metal on stage. The impression given by the film from Carl Denham to the audience is that the "chrome steel" has some unique properties of having a higher tensile strength than "normal steel" which is incorrect. Higher tensile strength steels are created by the addition of carbon. True to this deceptive description, King Kong breaks free anyway (in both versions). The term was also used in the ''Star Trek'' episode "A Private Little War," where the guns introduced to the primitive villagers by the Klingon The Klingons ( ; Klingon: ''tlhIngan'' ) are a fictional species in the science fiction franchise ''Star Tre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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